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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a href="/search/?searchtype=author&query=Crommie%2C+M+F&start=50" class="pagination-next" >Next </a> <ul class="pagination-list"> <li> <a href="/search/?searchtype=author&query=Crommie%2C+M+F&start=0" class="pagination-link is-current" aria-label="Goto page 1">1 </a> </li> <li> <a href="/search/?searchtype=author&query=Crommie%2C+M+F&start=50" class="pagination-link " aria-label="Page 2" aria-current="page">2 </a> </li> </ul> </nav> <ol class="breathe-horizontal" start="1"> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.18168">arXiv:2501.18168</a> <span> [<a href="https://arxiv.org/pdf/2501.18168">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Competition between excitonic insulators and quantum Hall states in correlated electron-hole bilayers </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Qi%2C+R">Ruishi Qi</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+Q">Qize Li</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Z">Zuocheng Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Cui%2C+Z">Zhiyuan Cui</a>, <a href="/search/cond-mat?searchtype=author&query=Zou%2C+B">Bo Zou</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+H">Haleem Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Sanborn%2C+C">Collin Sanborn</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+S">Sudi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Xie%2C+J">Jingxu Xie</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=MacDonald%2C+A+H">Allan H. MacDonald</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.18168v1-abstract-short" style="display: inline;"> Excitonic insulators represent a unique quantum phase of matter, providing a rich ground for studying exotic quantum bosonic states. Strongly coupled electron-hole bilayers, which host stable dipolar exciton fluids with an exciton density that can be adjusted electrostatically, offer an ideal platform to investigate correlated excitonic insulators. Based on electron-hole bilayers made of MoSe2/hBN… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.18168v1-abstract-full').style.display = 'inline'; document.getElementById('2501.18168v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.18168v1-abstract-full" style="display: none;"> Excitonic insulators represent a unique quantum phase of matter, providing a rich ground for studying exotic quantum bosonic states. Strongly coupled electron-hole bilayers, which host stable dipolar exciton fluids with an exciton density that can be adjusted electrostatically, offer an ideal platform to investigate correlated excitonic insulators. Based on electron-hole bilayers made of MoSe2/hBN/WSe2 heterostructures, here we study the behavior of excitonic insulators in a perpendicular magnetic field. We report the observation of excitonic quantum oscillations in both Coulomb drag signals and electrical resistance at low to medium magnetic fields. Under a strong magnetic field, we identify multiple quantum phase transitions between the excitonic insulator phase and the bilayer quantum Hall insulator phase. These findings underscore the interplay between the electron-hole interactions and Landau level quantization that opens new possibilities for exploring quantum phenomena in composite bosonic insulators. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.18168v1-abstract-full').style.display = 'none'; document.getElementById('2501.18168v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2501.16702">arXiv:2501.16702</a> <span> [<a href="https://arxiv.org/pdf/2501.16702">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Spin frustration and unconventional spin twisting state in van der Waals ferromagnet/antiferromagnet heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+T">Tianye Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+Q">Qian Li</a>, <a href="/search/cond-mat?searchtype=author&query=Yang%2C+M">Mengmeng Yang</a>, <a href="/search/cond-mat?searchtype=author&query=Sun%2C+Y">Yu Sun</a>, <a href="/search/cond-mat?searchtype=author&query=N%27Diaye%2C+A+T">Alpha T. N'Diaye</a>, <a href="/search/cond-mat?searchtype=author&query=Klewe%2C+C">Christoph Klewe</a>, <a href="/search/cond-mat?searchtype=author&query=Scholl%2C+A">Andreas Scholl</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+X">Xianzhe Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Huang%2C+X">Xiaoxi Huang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+H">Hongrui Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Yang%2C+S">Santai Yang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+X">Xixiang Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Chanyong Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Shafer%2C+P+C">Padraic C. Shafer</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Ramesh%2C+R">Ramamoorthy Ramesh</a>, <a href="/search/cond-mat?searchtype=author&query=Qiu%2C+Z+Q">Zi Q. Qiu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2501.16702v1-abstract-short" style="display: inline;"> Atomically flat surfaces of van der Waals (vdW) materials pave an avenue for addressing a long-standing fundamental issue of how a perfectly compensated antiferromagnet (AFM) surface frustrates a ferromagnetic (FM) overlayer in FM/AFM heterostructures. By revealing the AFM and FM spin structures separately in vdW Fe5GeTe2/NiPS3 heterostructures, we find that C-type in-plane AFM NiPS3 develops thre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.16702v1-abstract-full').style.display = 'inline'; document.getElementById('2501.16702v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2501.16702v1-abstract-full" style="display: none;"> Atomically flat surfaces of van der Waals (vdW) materials pave an avenue for addressing a long-standing fundamental issue of how a perfectly compensated antiferromagnet (AFM) surface frustrates a ferromagnetic (FM) overlayer in FM/AFM heterostructures. By revealing the AFM and FM spin structures separately in vdW Fe5GeTe2/NiPS3 heterostructures, we find that C-type in-plane AFM NiPS3 develops three equivalent AFM domains which are robust against external magnetic field and magnetic coupling with Fe5GeTe2. Consequently, spin frustration at the Fe5GeTe2/NiPS3 interface was shown to develop a perpendicular Fe5GeTe2 magnetization in the interfacial region that switches separately from the bulk of the Fe5GeTe2 magnetizations. In particular, we discover an unconventional spin twisting state that the Fe5GeTe2 spins twist from perpendicular direction near the interface to in-plane direction away from the interface in Fe5GeTe2/NiPS3. Our finding of the twisting spin texture is a unique property of spin frustration in van der Waals magnetic heterostructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2501.16702v1-abstract-full').style.display = 'none'; document.getElementById('2501.16702v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 January, 2025; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2025. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">28 pages, 8 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2407.19207">arXiv:2407.19207</a> <span> [<a href="https://arxiv.org/pdf/2407.19207">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Controlling structure and interfacial interaction of monolayer TaSe2 on bilayer graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lee%2C+H">Hyobeom Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Im%2C+H">Hayoon Im</a>, <a href="/search/cond-mat?searchtype=author&query=Choi%2C+B+K">Byoung Ki Choi</a>, <a href="/search/cond-mat?searchtype=author&query=Park%2C+K">Kyoungree Park</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Zhong%2C+Y">Yong Zhong</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Ji-Eun Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+J">Jinwoong Hwang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2407.19207v1-abstract-short" style="display: inline;"> Tunability of interfacial effects between two-dimensional (2D) crystals is crucial not only for understanding the intrinsic properties of each system, but also for designing electronic devices based on ultra-thin heterostructures. A prerequisite of such heterostructure engineering is the availability of 2D crystals with different degrees of interfacial interactions. In this work, we report a contr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.19207v1-abstract-full').style.display = 'inline'; document.getElementById('2407.19207v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2407.19207v1-abstract-full" style="display: none;"> Tunability of interfacial effects between two-dimensional (2D) crystals is crucial not only for understanding the intrinsic properties of each system, but also for designing electronic devices based on ultra-thin heterostructures. A prerequisite of such heterostructure engineering is the availability of 2D crystals with different degrees of interfacial interactions. In this work, we report a controlled epitaxial growth of monolayer TaSe2 with different structural phases, 1H and 1T, on a bilayer graphene (BLG) substrate using molecular beam epitaxy, and its impact on the electronic properties of the heterostructures using angle-resolved photoemission spectroscopy. 1H-TaSe2 exhibits significant charge transfer and band hybridization at the interface, whereas 1T-TaSe2 shows weak interactions with the substrate. The distinct interfacial interactions are attributed to the dual effects from the differences of the work functions as well as the relative interlayer distance between TaSe2 films and BLG substrate. The method demonstrated here provides a viable route towards interface engineering in a variety of transition-metal dichalcogenides that can be applied to future nano-devices with designed electronic properties. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2407.19207v1-abstract-full').style.display = 'none'; document.getElementById('2407.19207v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 July, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nano Convergence 11, 14 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2404.16344">arXiv:2404.16344</a> <span> [<a href="https://arxiv.org/pdf/2404.16344">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Imaging Tunable Luttinger Liquid Systems in van der Waals Heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Xiang%2C+Z">Ziyu Xiang</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+T">Tianle Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+W">Woochang Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Nie%2C+J">Jiahui Nie</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shiyu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Ge%2C+Z">Zhehao Ge</a>, <a href="/search/cond-mat?searchtype=author&query=He%2C+Z">Zehao He</a>, <a href="/search/cond-mat?searchtype=author&query=Ou%2C+Y">Yunbo Ou</a>, <a href="/search/cond-mat?searchtype=author&query=Banerjee%2C+R">Rounak Banerjee</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Zaletel%2C+M+P">Michael P. Zaletel</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2404.16344v1-abstract-short" style="display: inline;"> One-dimensional (1D) interacting electrons are often described as a Luttinger liquid1-4 having properties that are intrinsically different from Fermi liquids in higher dimensions5,6. 1D electrons in materials systems exhibit exotic quantum phenomena that can be tuned by both intra- and inter-1D-chain electronic interactions, but their experimental characterization can be challenging. Here we demon… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.16344v1-abstract-full').style.display = 'inline'; document.getElementById('2404.16344v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2404.16344v1-abstract-full" style="display: none;"> One-dimensional (1D) interacting electrons are often described as a Luttinger liquid1-4 having properties that are intrinsically different from Fermi liquids in higher dimensions5,6. 1D electrons in materials systems exhibit exotic quantum phenomena that can be tuned by both intra- and inter-1D-chain electronic interactions, but their experimental characterization can be challenging. Here we demonstrate that layer-stacking domain walls (DWs) in van der Waals heterostructures form a broadly tunable Luttinger liquid system including both isolated and coupled arrays. We have imaged the evolution of DW Luttinger liquids under different interaction regimes tuned by electron density using a novel scanning tunneling microscopy (STM) technique. Single DWs at low carrier density are highly susceptible to Wigner crystallization consistent with a spin-incoherent Luttinger liquid, while at intermediate densities dimerized Wigner crystals form due to an enhanced magneto-elastic coupling. Periodic arrays of DWs exhibit an interplay between intra- and inter-chain interactions that gives rise to new quantum phases. At low electron densities inter-chain interactions are dominant and induce a 2D electron crystal composed of phased-locked 1D Wigner crystal in a staggered configuration. Increased electron density causes intra-chain fluctuation potentials to dominate, leading to an electronic smectic liquid crystal phase where electrons are ordered with algebraical correlation decay along the chain direction but disordered between chains. Our work shows that layer-stacking DWs in 2D heterostructures offers new opportunities to explore Luttinger liquid physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2404.16344v1-abstract-full').style.display = 'none'; document.getElementById('2404.16344v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 25 April, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.15882">arXiv:2402.15882</a> <span> [<a href="https://arxiv.org/pdf/2402.15882">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Regioselective On-Surface Synthesis of [3]Triangulene Graphene Nanoribbons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Daugherty%2C+M+C">Michael C. Daugherty</a>, <a href="/search/cond-mat?searchtype=author&query=Jacobse%2C+P+H">Peter H. Jacobse</a>, <a href="/search/cond-mat?searchtype=author&query=Jiang%2C+J">Jingwei Jiang</a>, <a href="/search/cond-mat?searchtype=author&query=Jornet-Somoza%2C+J">Joaquim Jornet-Somoza</a>, <a href="/search/cond-mat?searchtype=author&query=Dorit%2C+R">Reis Dorit</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Z">Ziyi Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+J">Jiaming Lu</a>, <a href="/search/cond-mat?searchtype=author&query=McCurdy%2C+R">Ryan McCurdy</a>, <a href="/search/cond-mat?searchtype=author&query=Rubio%2C+A">Angel Rubio</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.15882v1-abstract-short" style="display: inline;"> The integration of low-energy states into bottom-up engineered graphene nanoribbons (GNRs) is a robust strategy for realizing materials with tailored electronic band structure for nanoelectronics. Low-energy zero-modes (ZMs) can be introduced into nanographenes (NGs) by creating an imbalance between the two sublattices of graphene. This phenomenon is exemplified by the family of [n]triangulenes. H… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.15882v1-abstract-full').style.display = 'inline'; document.getElementById('2402.15882v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.15882v1-abstract-full" style="display: none;"> The integration of low-energy states into bottom-up engineered graphene nanoribbons (GNRs) is a robust strategy for realizing materials with tailored electronic band structure for nanoelectronics. Low-energy zero-modes (ZMs) can be introduced into nanographenes (NGs) by creating an imbalance between the two sublattices of graphene. This phenomenon is exemplified by the family of [n]triangulenes. Here, we demonstrate the synthesis of [3]triangulene-GNRs, a regioregular one-dimensional (1D) chain of [3]triangulenes linked by five-membered rings. Hybridization between ZMs on adjacent [3]triangulenes leads to the emergence of a narrow band gap, Eg = 0.7 eV, and topological end states that are experimentally verified using scanning tunneling spectroscopy (STS). Tight-binding and first-principles density functional theory (DFT) calculations within the local spin density approximation (LSDA) corroborate our experimental observations. Our synthetic design takes advantage of a selective on-surface head-to-tail coupling of monomer building blocks enabling the regioselective synthesis of [3]triangulene-GNRs. Detailed ab initio theory provides insight into the mechanism of on-surface radical polymerization, revealing the pivotal role of Au-C bond formation/breakage in driving selectivity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.15882v1-abstract-full').style.display = 'none'; document.getElementById('2402.15882v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">22 Pages, 4 Figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2402.05456">arXiv:2402.05456</a> <span> [<a href="https://arxiv.org/pdf/2402.05456">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Quantum Melting of a Disordered Wigner Solid </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Xiang%2C+Z">Ziyu Xiang</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Xiao%2C+J">Jianghan Xiao</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Ge%2C+Z">Zhehao Ge</a>, <a href="/search/cond-mat?searchtype=author&query=He%2C+Z">Zehao He</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+S">Sudi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Nie%2C+J">Jiahui Nie</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shiyu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Jiang%2C+Y">Yifan Jiang</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Banerjee%2C+R">Rounak Banerjee</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2402.05456v1-abstract-short" style="display: inline;"> The behavior of two-dimensional electron gas (2DEG) in extreme coupling limits are reasonably well-understood, but our understanding of intermediate region remains limited. Strongly interacting electrons crystalize into a solid phase known as the Wigner crystal at very low densities, and these evolve to a Fermi liquid at high densities. At intermediate densities, however, where the Wigner crystal… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05456v1-abstract-full').style.display = 'inline'; document.getElementById('2402.05456v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2402.05456v1-abstract-full" style="display: none;"> The behavior of two-dimensional electron gas (2DEG) in extreme coupling limits are reasonably well-understood, but our understanding of intermediate region remains limited. Strongly interacting electrons crystalize into a solid phase known as the Wigner crystal at very low densities, and these evolve to a Fermi liquid at high densities. At intermediate densities, however, where the Wigner crystal melts into a strongly correlated electron fluid that is poorly understood partly due to a lack of microscopic probes for delicate quantum phases. Here we report the first imaging of a disordered Wigner solid and its quantum densification and quantum melting behavior in a bilayer MoSe2 using a non-invasive scanning tunneling microscopy (STM) technique. We observe a Wigner solid with nanocrystalline domains pinned by local disorder at low hole densities. With slightly increasing electrostatic gate voltages, the holes are added quantum mechanically during the densification of the disordered Wigner solid. As the hole density is increased above a threshold (p ~ 5.7 * 10e12 (cm-2)), the Wigner solid is observed to melt locally and create a mixed phase where solid and liquid regions coexist. With increasing density, the liquid regions gradually expand and form an apparent percolation network. Local solid domains appear to be pinned and stabilized by local disorder over a range of densities. Our observations are consistent with a microemulsion picture of Wigner solid quantum melting where solid and liquid domains emerge spontaneously and solid domains are pinned by local disorder. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2402.05456v1-abstract-full').style.display = 'none'; document.getElementById('2402.05456v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 8 February, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2312.07607">arXiv:2312.07607</a> <span> [<a href="https://arxiv.org/pdf/2312.07607">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Wigner Molecular Crystals from Multi-electron Moir茅 Artificial Atoms </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Xiang%2C+Z">Ziyu Xiang</a>, <a href="/search/cond-mat?searchtype=author&query=Reddy%2C+A+P">Aidan P. Reddy</a>, <a href="/search/cond-mat?searchtype=author&query=Devakul%2C+T">Trithep Devakul</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Banerjee%2C+R">Rounak Banerjee</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Fu%2C+L">Liang Fu</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2312.07607v1-abstract-short" style="display: inline;"> Semiconductor moir茅 superlattices provide a versatile platform to engineer new quantum solids composed of artificial atoms on moir茅 sites. Previous studies have mostly focused on the simplest correlated quantum solid - the Fermi-Hubbard model - where intra-atom interactions are simplified to a single onsite repulsion energy U. These studies have revealed novel quantum phases ranging from Mott insu… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.07607v1-abstract-full').style.display = 'inline'; document.getElementById('2312.07607v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2312.07607v1-abstract-full" style="display: none;"> Semiconductor moir茅 superlattices provide a versatile platform to engineer new quantum solids composed of artificial atoms on moir茅 sites. Previous studies have mostly focused on the simplest correlated quantum solid - the Fermi-Hubbard model - where intra-atom interactions are simplified to a single onsite repulsion energy U. These studies have revealed novel quantum phases ranging from Mott insulators to quantum anomalous Hall insulators at a filling of one electron per moir茅 unit cell. New types of quantum solids should arise at even higher filling factors where the multi-electron configuration of moir茅 artificial atoms provides new degrees of freedom. Here we report the experimental observation of Wigner molecular crystals emerging from multi-electron artificial atoms in twisted bilayer WS2 moir茅 superlattices. Moir茅 artificial atoms, unlike natural atoms, can host qualitatively different electron states due to the interplay between quantized energy levels and Coulomb interactions. Using scanning tunneling microscopy (STM), we demonstrate that Wigner molecules appear in multi-electron artificial atoms when Coulomb interactions dominate. Three-electron Wigner molecules, for example, are seen to exhibit a characteristic trimer pattern. The array of Wigner molecules observed in a moir茅 superlattice comprises a new crystalline phase of electrons: the Wigner molecular crystal. We show that these Wigner molecular crystals are highly tunable through mechanical strain, moir茅 period, and carrier charge type. Our study presents new opportunities for exploring quantum phenomena in moir茅 quantum solids composed of multi-electron artificial atoms. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2312.07607v1-abstract-full').style.display = 'none'; document.getElementById('2312.07607v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 December, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2310.04939">arXiv:2310.04939</a> <span> [<a href="https://arxiv.org/pdf/2310.04939">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Applied Physics">physics.app-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-024-07604-9">10.1038/s41586-024-07604-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Terahertz phonon engineering with van der Waals heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Yoon%2C+Y">Yoseob Yoon</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+Z">Zheyu Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Uzundal%2C+C">Can Uzundal</a>, <a href="/search/cond-mat?searchtype=author&query=Qi%2C+R">Ruishi Qi</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">Wenyu Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+S">Sudi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Feng%2C+Q">Qixin Feng</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+W">Woochang Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2310.04939v2-abstract-short" style="display: inline;"> Phononic engineering at gigahertz (GHz) frequencies form the foundation of microwave acoustic filters, acousto-optic modulators, and quantum transducers. Terahertz (THz) phononic engineering could lead to acoustic filters and modulators at higher bandwidth and speed, as well as quantum circuits operating at higher temperatures. Despite its potential, methods for engineering THz phonons have been l… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.04939v2-abstract-full').style.display = 'inline'; document.getElementById('2310.04939v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2310.04939v2-abstract-full" style="display: none;"> Phononic engineering at gigahertz (GHz) frequencies form the foundation of microwave acoustic filters, acousto-optic modulators, and quantum transducers. Terahertz (THz) phononic engineering could lead to acoustic filters and modulators at higher bandwidth and speed, as well as quantum circuits operating at higher temperatures. Despite its potential, methods for engineering THz phonons have been limited due to the challenges of achieving the required material control at sub-nanometer precision and efficient phonon coupling at THz frequencies. Here, we demonstrate efficient generation, detection, and manipulation of THz phonons through precise integration of atomically thin layers in van der Waals heterostructures. We employ few-layer graphene (FLG) as an ultrabroadband phonon transducer, converting femtosecond near-infrared pulses to acoustic phonon pulses with spectral content up to 3 THz. A monolayer WSe$_2$ is used as a sensor, where high-fidelity readout is enabled by the exciton-phonon coupling and strong light-matter interactions. Combining these capabilities in a single heterostructure and detecting responses to incident mechanical waves, we perform THz phononic spectroscopy. Using this platform, we demonstrate high-Q THz phononic cavities and show that a monolayer WSe$_2$ embedded in hexagonal boron nitride (hBN) can efficiently block the transmission of THz phonons. By comparing our measurements to a nanomechanical model, we obtain the force constants at the heterointerfaces. Our results could enable THz phononic metamaterials for ultrabroadband acoustic filters and modulators, and open novel routes for thermal engineering. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2310.04939v2-abstract-full').style.display = 'none'; document.getElementById('2310.04939v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 August, 2024; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 October, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature 631, 771 (2024) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.13265">arXiv:2306.13265</a> <span> [<a href="https://arxiv.org/pdf/2306.13265">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Thermodynamic behavior of correlated electron-hole fluids in van der Waals heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Qi%2C+R">Ruishi Qi</a>, <a href="/search/cond-mat?searchtype=author&query=Joe%2C+A+Y">Andrew Y. Joe</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Z">Zuocheng Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zeng%2C+Y">Yongxin Zeng</a>, <a href="/search/cond-mat?searchtype=author&query=Zheng%2C+T">Tiancheng Zheng</a>, <a href="/search/cond-mat?searchtype=author&query=Feng%2C+Q">Qixin Feng</a>, <a href="/search/cond-mat?searchtype=author&query=Regan%2C+E">Emma Regan</a>, <a href="/search/cond-mat?searchtype=author&query=Xie%2C+J">Jingxu Xie</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+Z">Zheyu Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=MacDonald%2C+A+H">Allan H. MacDonald</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.13265v1-abstract-short" style="display: inline;"> Coupled two-dimensional electron-hole bilayers provide a unique platform to study strongly correlated Bose-Fermi mixtures in condensed matter. Electrons and holes in spatially separated layers can bind to form interlayer excitons, composite Bosons expected to support high-temperature exciton superfluids. The interlayer excitons can also interact strongly with excess charge carriers when electron a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.13265v1-abstract-full').style.display = 'inline'; document.getElementById('2306.13265v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.13265v1-abstract-full" style="display: none;"> Coupled two-dimensional electron-hole bilayers provide a unique platform to study strongly correlated Bose-Fermi mixtures in condensed matter. Electrons and holes in spatially separated layers can bind to form interlayer excitons, composite Bosons expected to support high-temperature exciton superfluids. The interlayer excitons can also interact strongly with excess charge carriers when electron and hole densities are unequal. Here, we use optical spectroscopy to quantitatively probe the local thermodynamic properties of strongly correlated electron-hole fluids in MoSe2/hBN/WSe2 heterostructures. We observe a discontinuity in the electron and hole chemical potentials at matched electron and hole densities, a definitive signature of an excitonic insulator ground state. The excitonic insulator is stable up to a Mott density of ~$0.8\times {10}^{12} \mathrm{cm}^{-2}$ and has a thermal ionization temperature of ~70 K. The density dependence of the electron, hole, and exciton chemical potentials reveals strong correlation effects across the phase diagram. Compared with a non-interacting uniform charge distribution, the correlation effects lead to significant attractive exciton-exciton and exciton-charge interactions in the electron-hole fluid. Our work highlights the unique quantum behavior that can emerge in strongly correlated electron-hole systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.13265v1-abstract-full').style.display = 'none'; document.getElementById('2306.13265v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.00859">arXiv:2306.00859</a> <span> [<a href="https://arxiv.org/pdf/2306.00859">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Imaging Moir茅 Excited States with Photocurrent Tunneling Microscopy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Xiang%2C+Z">Ziyu Xiang</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+W">Woochang Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+Z">Zhenglu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Banerjee%2C+R">Rounak Banerjee</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=da+Jornada%2C+F+H">Felipe H. da Jornada</a>, <a href="/search/cond-mat?searchtype=author&query=Louie1%2C+S+G">Steven G. Louie1</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2306.00859v1-abstract-short" style="display: inline;"> Moir茅 superlattices provide a highly tunable and versatile platform to explore novel quantum phases and exotic excited states ranging from correlated insulators1-17 to moir茅 excitons7-10,18. Scanning tunneling microscopy has played a key role in probing microscopic behaviors of the moir茅 correlated ground states at the atomic scale1,11-15,19. Atomic-resolution imaging of quantum excited state in m… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.00859v1-abstract-full').style.display = 'inline'; document.getElementById('2306.00859v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.00859v1-abstract-full" style="display: none;"> Moir茅 superlattices provide a highly tunable and versatile platform to explore novel quantum phases and exotic excited states ranging from correlated insulators1-17 to moir茅 excitons7-10,18. Scanning tunneling microscopy has played a key role in probing microscopic behaviors of the moir茅 correlated ground states at the atomic scale1,11-15,19. Atomic-resolution imaging of quantum excited state in moir茅 heterostructures, however, has been an outstanding experimental challenge. Here we develop a novel photocurrent tunneling microscopy by combining laser excitation and scanning tunneling spectroscopy (laser-STM) to directly visualize the electron and hole distribution within the photoexcited moir茅 exciton in a twisted bilayer WS2 (t-WS2). We observe that the tunneling photocurrent alternates between positive and negative polarities at different locations within a single moir茅 unit cell. This alternating photocurrent originates from the exotic in-plane charge-transfer (ICT) moir茅 exciton in the t-WS2 that emerges from the competition between the electron-hole Coulomb interaction and the moir茅 potential landscape. Our photocurrent maps are in excellent agreement with our GW-BSE calculations for excitonic states in t-WS2. The photocurrent tunneling microscopy creates new opportunities for exploring photoexcited non-equilibrium moir茅 phenomena at the atomic scale. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.00859v1-abstract-full').style.display = 'none'; document.getElementById('2306.00859v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2023. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2301.02721">arXiv:2301.02721</a> <span> [<a href="https://arxiv.org/pdf/2301.02721">pdf</a>, <a href="https://arxiv.org/format/2301.02721">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> WS$_2$ Band Gap Renormalization Induced by Tomonaga Luttinger Liquid Formation in Mirror Twin Boundaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Rossi%2C+A">Antonio Rossi</a>, <a href="/search/cond-mat?searchtype=author&query=Thomas%2C+J+C">John C. Thomas</a>, <a href="/search/cond-mat?searchtype=author&query=K%C3%BCchle%2C+J+T">Johannes T. K眉chle</a>, <a href="/search/cond-mat?searchtype=author&query=Barr%C3%A9%2C+E">Elyse Barr茅</a>, <a href="/search/cond-mat?searchtype=author&query=Yu%2C+Z">Zhuohang Yu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+D">Da Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Kumari%2C+S">Shalini Kumari</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+E">Ed Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Jozwiak%2C+C">Chris Jozwiak</a>, <a href="/search/cond-mat?searchtype=author&query=Bostwick%2C+A">Aaron Bostwick</a>, <a href="/search/cond-mat?searchtype=author&query=Robinson%2C+J+A">Joshua A. Robinson</a>, <a href="/search/cond-mat?searchtype=author&query=Terrones%2C+M">Mauricio Terrones</a>, <a href="/search/cond-mat?searchtype=author&query=Raja%2C+A">Archana Raja</a>, <a href="/search/cond-mat?searchtype=author&query=Schwartzberg%2C+A">Adam Schwartzberg</a>, <a href="/search/cond-mat?searchtype=author&query=Ogletree%2C+D+F">D. Frank Ogletree</a>, <a href="/search/cond-mat?searchtype=author&query=Neaton%2C+J+B">Jeffrey B. Neaton</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Allegretti%2C+F">Francesco Allegretti</a>, <a href="/search/cond-mat?searchtype=author&query=Auw%C3%A4rter%2C+W">Willi Auw盲rter</a>, <a href="/search/cond-mat?searchtype=author&query=Rotenberg%2C+E">Eli Rotenberg</a>, <a href="/search/cond-mat?searchtype=author&query=Weber-Bargioni%2C+A">Alexander Weber-Bargioni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2301.02721v2-abstract-short" style="display: inline;"> Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate requi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.02721v2-abstract-full').style.display = 'inline'; document.getElementById('2301.02721v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2301.02721v2-abstract-full" style="display: none;"> Tomonaga-Luttinger liquid (TLL) behavior in one-dimensional systems has been predicted and shown to occur at semiconductor-to-metal transitions within two-dimensional materials. Reports of mirror twin boundaries (MTBs) hosting a Fermi liquid or a TLL have suggested a dependence on the underlying substrate, however, unveiling the physical details of electronic contributions from the substrate require cross-correlative investigation. Here, we study TLL formation in MTBs within defectively engineered WS$_2$ atop graphene, where band structure and the atomic environment is visualized with nano angle-resolved photoelectron spectroscopy, scanning tunneling microscopy and scanning tunneling spectroscopy, and non-contact atomic force microscopy. Correlations between the local density of states and electronic band dispersion elucidated the electron transfer from graphene into a TLL hosted by MTB defects. We find that MTB defects can be substantially charged at a local level, which drives a band gap shift by $\sim$0.5 eV. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2301.02721v2-abstract-full').style.display = 'none'; document.getElementById('2301.02721v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 January, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2023. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Main text is 13 pages, 4 figures; Supplementary text is 14 pages, 11 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2212.03380">arXiv:2212.03380</a> <span> [<a href="https://arxiv.org/pdf/2212.03380">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Visualizing and manipulating chiral interface states in a moir茅 quantum anomalous Hall insulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Soejima%2C+T">Tomohiro Soejima</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zaletel%2C+M+P">Michael P. Zaletel</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2212.03380v2-abstract-short" style="display: inline;"> Moir茅 systems made from stacked two-dimensional materials host novel correlated and topological states that can be electrically controlled via applied gate voltages. We have used this technique to manipulate Chern domains in an interaction-driven quantum anomalous Hall insulator made from twisted monolayer-bilayer graphene (tMBLG). This has allowed the wavefunction of chiral interface states to be… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.03380v2-abstract-full').style.display = 'inline'; document.getElementById('2212.03380v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2212.03380v2-abstract-full" style="display: none;"> Moir茅 systems made from stacked two-dimensional materials host novel correlated and topological states that can be electrically controlled via applied gate voltages. We have used this technique to manipulate Chern domains in an interaction-driven quantum anomalous Hall insulator made from twisted monolayer-bilayer graphene (tMBLG). This has allowed the wavefunction of chiral interface states to be directly imaged using a scanning tunneling microscope (STM). To accomplish this tMBLG carrier concentration was tuned to stabilize neighboring domains of opposite Chern number, thus providing topological interfaces completely devoid of any structural boundaries. STM tip pulse-induced quantum dots were utilized to induce new Chern domains and thereby create new chiral interface states with tunable chirality at predetermined locations. Theoretical analysis confirms the chiral nature of observed interface states and enables the determination of the characteristic length scale of valley polarization reversal across neighboring tMBLG Chern domains. tMBLG is shown to be a useful platform for imaging the exotic topological properties of correlated moir茅 systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2212.03380v2-abstract-full').style.display = 'none'; document.getElementById('2212.03380v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 July, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 6 December, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">30 pages, 13 figures, 1 table</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2211.13198">arXiv:2211.13198</a> <span> [<a href="https://arxiv.org/pdf/2211.13198">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Imaging gate-induced molecular melting on a graphene field-effect transistor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Liou%2C+F">Franklin Liou</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Goodwin%2C+Z+A+H">Zachary A. H. Goodwin</a>, <a href="/search/cond-mat?searchtype=author&query=Aikawa%2C+A+S">Andrew S. Aikawa</a>, <a href="/search/cond-mat?searchtype=author&query=Ha%2C+E">Ethan Ha</a>, <a href="/search/cond-mat?searchtype=author&query=Hu%2C+M">Michael Hu</a>, <a href="/search/cond-mat?searchtype=author&query=Yang%2C+Y">Yiming Yang</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Lischner%2C+J">Johannes Lischner</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2211.13198v1-abstract-short" style="display: inline;"> Solid-liquid phase transitions are fundamental physical processes, but atomically-resolved microscopy has yet to capture both the solid and liquid dynamics for such a transition. We have developed a new technique for controlling the melting and freezing of 2D molecular layers on a graphene field-effect transistor (FET) that allows us to image phase transition dynamics via atomically-resolved scann… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13198v1-abstract-full').style.display = 'inline'; document.getElementById('2211.13198v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2211.13198v1-abstract-full" style="display: none;"> Solid-liquid phase transitions are fundamental physical processes, but atomically-resolved microscopy has yet to capture both the solid and liquid dynamics for such a transition. We have developed a new technique for controlling the melting and freezing of 2D molecular layers on a graphene field-effect transistor (FET) that allows us to image phase transition dynamics via atomically-resolved scanning tunneling microscopy. Back-gate voltages applied to a F4TCNQ-decorated graphene FET induce reversible transitions between a charge-neutral solid phase and a negatively charged liquid phase. Nonequilibrium molecular melting dynamics are visualized by rapidly heating the graphene surface with electrical current and imaging the resulting evolution toward new equilibrium states. An analytical model has been developed that explains the observed equilibrium mixed-state phases based on spectroscopic measurement of both solid and liquid molecular energy levels. Observed non-equilibrium melting dynamics are consistent with Monte Carlo simulations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2211.13198v1-abstract-full').style.display = 'none'; document.getElementById('2211.13198v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 23 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.06506">arXiv:2210.06506</a> <span> [<a href="https://arxiv.org/pdf/2210.06506">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-023-39110-3">10.1038/s41467-023-39110-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Local spectroscopy of a gate-switchable moir茅 quantum anomalous Hall insulator </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Soejima%2C+T">Tomohiro Soejima</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zaletel%2C+M+P">Michael P. Zaletel</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.06506v2-abstract-short" style="display: inline;"> In recent years, correlated insulating states, unconventional superconductivity, and topologically non-trivial phases have all been observed in several moir茅 heterostructures. However, understanding of the physical mechanisms behind these phenomena is hampered by the lack of local electronic structure data. Here, we use scanning tunnelling microscopy and spectroscopy to demonstrate how the interpl… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06506v2-abstract-full').style.display = 'inline'; document.getElementById('2210.06506v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.06506v2-abstract-full" style="display: none;"> In recent years, correlated insulating states, unconventional superconductivity, and topologically non-trivial phases have all been observed in several moir茅 heterostructures. However, understanding of the physical mechanisms behind these phenomena is hampered by the lack of local electronic structure data. Here, we use scanning tunnelling microscopy and spectroscopy to demonstrate how the interplay between correlation, topology, and local atomic structure determines the behaviour of electron-doped twisted monolayer-bilayer graphene. Through gate- and magnetic field-dependent measurements, we observe local spectroscopic signatures indicating a quantum anomalous Hall insulating state with a total Chern number of $\pm 2$ at a doping level of three electrons per moir茅 unit cell. We show that the sign of the Chern number and associated magnetism can be electrostatically switched only over a limited range of twist angle and sample hetero-strain values. This results from a competition between the orbital magnetization of filled bulk bands and chiral edge states, which is sensitive to strain-induced distortions in the moir茅 superlattice. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.06506v2-abstract-full').style.display = 'none'; document.getElementById('2210.06506v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 May, 2023; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 12 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Article 14 pages, 4 figures & Supplementary Information 13 pages, 9 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 14, 3595 (2023) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2210.02010">arXiv:2210.02010</a> <span> [<a href="https://arxiv.org/pdf/2210.02010">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1002/adma.202204579">10.1002/adma.202204579 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A novel $\sqrt{19}\times\sqrt{19}$ superstructure in epitaxially grown 1T-TaTe$_2$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+J">Jinwoong Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Jin%2C+Y">Yeongrok Jin</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+K">Kyoo Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Zhong%2C+Y">Yong Zhong</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Ji-Eun Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zongqi Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Jaekwang Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2210.02010v1-abstract-short" style="display: inline;"> The spontaneous formation of electronic orders is a crucial element for understanding complex quantum states and engineering heterostructures in two-dimensional materials. We report a novel $\sqrt{19}\times\sqrt{19}$ charge order in few-layer thick 1T-TaTe$_2$ transition metal dichalcogenide films grown by molecular beam epitaxy, which has not been realized. Our photoemission and scanning probe me… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02010v1-abstract-full').style.display = 'inline'; document.getElementById('2210.02010v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2210.02010v1-abstract-full" style="display: none;"> The spontaneous formation of electronic orders is a crucial element for understanding complex quantum states and engineering heterostructures in two-dimensional materials. We report a novel $\sqrt{19}\times\sqrt{19}$ charge order in few-layer thick 1T-TaTe$_2$ transition metal dichalcogenide films grown by molecular beam epitaxy, which has not been realized. Our photoemission and scanning probe measurements demonstrate that monolayer 1T-TaTe$_2$ exhibits a variety of metastable charge density wave orders, including the $\sqrt{19}\times\sqrt{19}$ superstructure, which can be selectively stabilized by controlling the post-growth annealing temperature. Moreover, we find that only the $\sqrt{19}\times\sqrt{19}$ order persists in 1T-TaTe$_2$ films thicker than a monolayer, up to 8 layers. Our findings identify the previously unrealized novel electronic order in a much-studied transition metal dichalcogenide and provide a viable route to control it within the epitaxial growth process. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2210.02010v1-abstract-full').style.display = 'none'; document.getElementById('2210.02010v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 4 October, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Advanced materials 34, 2204579 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2209.12830">arXiv:2209.12830</a> <span> [<a href="https://arxiv.org/pdf/2209.12830">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Mapping Charge Excitations in Generalized Wigner Crystals </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Xiang%2C+Z">Ziyu Xiang</a>, <a href="/search/cond-mat?searchtype=author&query=Regan%2C+E">Emma Regan</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">Wenyu Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Banerjee%2C+R">Rounak Banerjee</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2209.12830v2-abstract-short" style="display: inline;"> Transition metal dichalcogenide-based moire superlattices exhibit very strong electron-electron correlations, thus giving rise to strongly correlated quantum phenomena such as generalized Wigner crystal states. Theoretical studies predict that unusual quasiparticle excitations across the correlated gap between upper and lower Hubbard bands can arise due to long-range Coulomb interactions in genera… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.12830v2-abstract-full').style.display = 'inline'; document.getElementById('2209.12830v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.12830v2-abstract-full" style="display: none;"> Transition metal dichalcogenide-based moire superlattices exhibit very strong electron-electron correlations, thus giving rise to strongly correlated quantum phenomena such as generalized Wigner crystal states. Theoretical studies predict that unusual quasiparticle excitations across the correlated gap between upper and lower Hubbard bands can arise due to long-range Coulomb interactions in generalized Wigner crystal states. Here we describe a new scanning single-electron charging (SSEC) spectroscopy technique with nanometer spatial resolution and single-electron charge resolution that enables us to directly image electron and hole wavefunctions and to determine the thermodynamic gap of generalized Wigner crystal states in twisted WS2 moire heterostructures. High-resolution SSEC spectroscopy was achieved by combining scanning tunneling microscopy (STM) with a monolayer graphene sensing layer, thus enabling the generation of individual electron and hole quasiparticles in generalized Wigner crystals. We show that electron and hole quasiparticles have complementary wavefunction distributions and that thermodynamic gaps of order 50meV exist for the 1/3 and 2/3 generalized Wigner crystal states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.12830v2-abstract-full').style.display = 'none'; document.getElementById('2209.12830v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 26 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2207.05938">arXiv:2207.05938</a> <span> [<a href="https://arxiv.org/pdf/2207.05938">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Quantum Physics">quant-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.1c02271">10.1021/acs.nanolett.1c02271 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging Quantum Interference in Stadium-Shaped Monolayer and Bilayer Graphene Quantum Dots </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Ge%2C+Z">Zhehao Ge</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Juwon Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Joucken%2C+F">Frederic Joucken</a>, <a href="/search/cond-mat?searchtype=author&query=Quezada-Lopez%2C+E+A">Eberth A. Quezada-Lopez</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Velasco%2C+J">Jairo Velasco Jr</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2207.05938v1-abstract-short" style="display: inline;"> Experimental realization of graphene-based stadium-shaped quantum dots (QDs) have been few and incompatible with scanned probe microscopy. Yet, direct visualization of electronic states within these QDs is crucial for determining the existence of quantum chaos in these systems. We report the fabrication and characterization of electrostatically defined stadium-shaped QDs in heterostructure devices… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.05938v1-abstract-full').style.display = 'inline'; document.getElementById('2207.05938v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2207.05938v1-abstract-full" style="display: none;"> Experimental realization of graphene-based stadium-shaped quantum dots (QDs) have been few and incompatible with scanned probe microscopy. Yet, direct visualization of electronic states within these QDs is crucial for determining the existence of quantum chaos in these systems. We report the fabrication and characterization of electrostatically defined stadium-shaped QDs in heterostructure devices composed of monolayer graphene (MLG) and bilayer graphene (BLG). To realize a stadium-shaped QD, we utilized the tip of a scanning tunneling microscope to charge defects in a supporting hexagonal boron nitride flake. The stadium states visualized are consistent with tight-binding-based simulations, but lack clear quantum chaos signatures. The absence of quantum chaos features in MLG-based stadium QDs is attributed to the leaky nature of the confinement potential due to Klein tunneling. In contrast, for BLG-based stadium QDs (which have stronger confinement) quantum chaos is precluded by the smooth confinement potential which reduces interference and mixing between states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2207.05938v1-abstract-full').style.display = 'none'; document.getElementById('2207.05938v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 July, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nano Letters 2021 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.13126">arXiv:2205.13126</a> <span> [<a href="https://arxiv.org/pdf/2205.13126">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.106.075153">10.1103/PhysRevB.106.075153 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of a multitude of correlated states at the surface of bulk 1T-TaSe$_2$ crystals </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Cain%2C+J+D">Jeffrey D. Cain</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+R+L">Ryan L. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Jia%2C+C">Caihong Jia</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2205.13126v2-abstract-short" style="display: inline;"> The interplay between electron-electron interactions and structural ordering can yield exceptionally rich correlated electronic phases. We have used scanning tunneling microscopy to investigate bulk 1T-TaSe2 and have uncovered surprisingly diverse correlated surface states thereof. These surface states exhibit the same in-plane charge density wave ordering but dramatically different electronic gro… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13126v2-abstract-full').style.display = 'inline'; document.getElementById('2205.13126v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.13126v2-abstract-full" style="display: none;"> The interplay between electron-electron interactions and structural ordering can yield exceptionally rich correlated electronic phases. We have used scanning tunneling microscopy to investigate bulk 1T-TaSe2 and have uncovered surprisingly diverse correlated surface states thereof. These surface states exhibit the same in-plane charge density wave ordering but dramatically different electronic ground states ranging from insulating to metallic. The insulating variety of surface state shows signatures of a decoupled surface Mott layer. The metallic surface states, on the other hand, exhibit zero-bias peaks of varying strength that suggest Kondo phases arising from coupling between the Mott surface layer and the metallic bulk of 1T-TaSe2. The surface of bulk 1T-TaSe2 thus constitutes a rare realization of the periodic Anderson model covering a wide parameter regime, thereby providing a model system for accessing different correlated phenomena in the same crystal. Our results highlight the central role played by strong correlations in this material family. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.13126v2-abstract-full').style.display = 'none'; document.getElementById('2205.13126v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 5 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 106, 075153 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2203.16769">arXiv:2203.16769</a> <span> [<a href="https://arxiv.org/pdf/2203.16769">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-022-28542-y">10.1038/s41467-022-28542-y <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Large-gap insulating dimer ground state in monolayer IrTe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+J">Jinwoong Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+K">Kyoo Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Herbig%2C+C">Charlotte Herbig</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+S">Sooran Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+B">Bongjae Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Zhong%2C+Y">Yong Zhong</a>, <a href="/search/cond-mat?searchtype=author&query=Salah%2C+M">Mohamed Salah</a>, <a href="/search/cond-mat?searchtype=author&query=El-Desoky%2C+M+M">Mohamed M. El-Desoky</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2203.16769v1-abstract-short" style="display: inline;"> Monolayers of two-dimensional van der Waals materials exhibit novel electronic phases distinct from their bulk due to the symmetry breaking and reduced screening in the absence of the interlayer coupling. In this work, we combine angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy to demonstrate the emergence of a unique insulating 2 x 1 dimer ground state in m… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.16769v1-abstract-full').style.display = 'inline'; document.getElementById('2203.16769v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2203.16769v1-abstract-full" style="display: none;"> Monolayers of two-dimensional van der Waals materials exhibit novel electronic phases distinct from their bulk due to the symmetry breaking and reduced screening in the absence of the interlayer coupling. In this work, we combine angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy to demonstrate the emergence of a unique insulating 2 x 1 dimer ground state in monolayer 1T-IrTe2 that has a large band gap in contrast to the metallic bilayer-to-bulk forms of this material. First-principles calculations reveal that phonon and charge instabilities as well as local bond formation collectively enhance and stabilize a charge-ordered ground state. Our findings provide important insights into the subtle balance of interactions having similar energy scales that occurs in the absence of strong interlayer coupling, which offers new opportunities to engineer the properties of 2D monolayers. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2203.16769v1-abstract-full').style.display = 'none'; document.getElementById('2203.16769v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 30 March, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature communications 13, 906 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2202.07224">arXiv:2202.07224</a> <span> [<a href="https://arxiv.org/pdf/2202.07224">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-022-01751-4">10.1038/s41567-022-01751-4 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Evidence for a spinon Kondo effect in cobalt atoms on single-layer 1T-TaSe$_2$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=He%2C+W">Wen-Yu He</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+J">Jinwoong Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+R+L">Ryan L. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+M">Meng Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+P+A">Patrick A. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2202.07224v1-abstract-short" style="display: inline;"> Quantum spin liquids (QSLs) are highly entangled, disordered magnetic states that arise in frustrated Mott insulators and host exotic fractional excitations such as spinons and chargons. Despite being charge insulators some QSLs are predicted to exhibit gapless itinerant spinons that yield metallic behavior in the spin channel. We have deposited isolated magnetic atoms onto single-layer (SL) 1T-Ta… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.07224v1-abstract-full').style.display = 'inline'; document.getElementById('2202.07224v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2202.07224v1-abstract-full" style="display: none;"> Quantum spin liquids (QSLs) are highly entangled, disordered magnetic states that arise in frustrated Mott insulators and host exotic fractional excitations such as spinons and chargons. Despite being charge insulators some QSLs are predicted to exhibit gapless itinerant spinons that yield metallic behavior in the spin channel. We have deposited isolated magnetic atoms onto single-layer (SL) 1T-TaSe$_2$, a gapless QSL candidate, to experimentally probe how itinerant spinons couple to impurity spin centers. Using scanning tunneling spectroscopy we observe the emergence of new, impurity-induced resonance peaks at the 1T-TaSe$_2$ Hubbard band edges when cobalt adatoms are positioned to have maximal spatial overlap with the Hubbard band charge distribution. These resonance peaks disappear when the spatial overlap is reduced or when the magnetic impurities are replaced with non-magnetic impurities. Theoretical simulations using a modified Anderson impurity model integrated with a gapless quantum spin liquid show that these resonance peaks are consistent with a Kondo resonance induced by spinons combined with spinon-chargon binding effects that arise due to QSL gauge-field fluctuations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2202.07224v1-abstract-full').style.display = 'none'; document.getElementById('2202.07224v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 February, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2022. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 18, 1335 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2111.09149">arXiv:2111.09149</a> <span> [<a href="https://arxiv.org/pdf/2111.09149">pdf</a>, <a href="https://arxiv.org/format/2111.09149">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Gate-tunable artificial nucleus in graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Telychko%2C+M">Mykola Telychko</a>, <a href="/search/cond-mat?searchtype=author&query=Noori%2C+K">Keian Noori</a>, <a href="/search/cond-mat?searchtype=author&query=Biswas%2C+H">Hillol Biswas</a>, <a href="/search/cond-mat?searchtype=author&query=Dulal%2C+D">Dikshant Dulal</a>, <a href="/search/cond-mat?searchtype=author&query=Lyu%2C+P">Pin Lyu</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+J">Jing Li</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Fang%2C+H">Hanyan Fang</a>, <a href="/search/cond-mat?searchtype=author&query=Qiu%2C+Z">Zhizhan Qiu</a>, <a href="/search/cond-mat?searchtype=author&query=Yap%2C+Z+W">Zhun Wai Yap</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Rodin%2C+A">Aleksandr Rodin</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+J">Jiong Lu</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2111.09149v1-abstract-short" style="display: inline;"> We report an atomically-precise integration of individual nitrogen (N) dopant as an in-plane artificial nucleus in a graphene device by atomic implantation to probe its gate-tunable quantum states and correlation effects. The N dopant creates the characteristic resonance state in the conduction band, revealing a giant carrier-dependent energetic renormalization up to 350 meV with respect to the Di… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.09149v1-abstract-full').style.display = 'inline'; document.getElementById('2111.09149v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2111.09149v1-abstract-full" style="display: none;"> We report an atomically-precise integration of individual nitrogen (N) dopant as an in-plane artificial nucleus in a graphene device by atomic implantation to probe its gate-tunable quantum states and correlation effects. The N dopant creates the characteristic resonance state in the conduction band, revealing a giant carrier-dependent energetic renormalization up to 350 meV with respect to the Dirac point, accompanied by the observation of long-range screening effects. Joint density functional theory and tight-binding calculations with modified perturbation potential corroborate experimental findings and highlight the short-range character of N-induced perturbation. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2111.09149v1-abstract-full').style.display = 'none'; document.getElementById('2111.09149v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2109.07631">arXiv:2109.07631</a> <span> [<a href="https://arxiv.org/pdf/2109.07631">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.1c03039">10.1021/acs.nanolett.1c03039 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging reconfigurable molecular concentration on a graphene field-effect transistor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Liou%2C+F">Franklin Liou</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Aikawa%2C+A+S">Andrew S. Aikawa</a>, <a href="/search/cond-mat?searchtype=author&query=Natividad%2C+K+C">Kyler C. Natividad</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+E">Eric Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Ha%2C+E">Ethan Ha</a>, <a href="/search/cond-mat?searchtype=author&query=Riss%2C+A">Alexander Riss</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Lischner%2C+J">Johannes Lischner</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2109.07631v1-abstract-short" style="display: inline;"> The spatial arrangement of adsorbates deposited onto a clean surface in vacuum typically cannot be reversibly tuned. Here we use scanning tunneling microscopy to demonstrate that molecules deposited onto graphene field-effect transistors exhibit reversible, electrically-tunable surface concentration. Continuous gate-tunable control over the surface concentration of charged F4TCNQ molecules was ach… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.07631v1-abstract-full').style.display = 'inline'; document.getElementById('2109.07631v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2109.07631v1-abstract-full" style="display: none;"> The spatial arrangement of adsorbates deposited onto a clean surface in vacuum typically cannot be reversibly tuned. Here we use scanning tunneling microscopy to demonstrate that molecules deposited onto graphene field-effect transistors exhibit reversible, electrically-tunable surface concentration. Continuous gate-tunable control over the surface concentration of charged F4TCNQ molecules was achieved on a graphene FET at T = 4.5K. This capability enables precisely controlled impurity doping of graphene devices and also provides a new method for determining molecular energy level alignment based on the gate-dependence of molecular concentration. The gate-tunable molecular concentration can be explained by a dynamical molecular rearrangement process that reduces total electronic energy by maintaining Fermi level pinning in the device substrate. Molecular surface concentration in this case is fully determined by the device back-gate voltage, its geometric capacitance, and the energy difference between the graphene Dirac point and the molecular LUMO level. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2109.07631v1-abstract-full').style.display = 'none'; document.getElementById('2109.07631v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 September, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2108.03829">arXiv:2108.03829</a> <span> [<a href="https://arxiv.org/pdf/2108.03829">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41563-022-01277-3">10.1038/s41563-022-01277-3 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging gate-tunable Tomonaga-Luttinger liquids in 1H-MoSe$_2$ mirror twin boundaries </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Y">Yan-Qi Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+S">Shuopei Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+T">Tianye Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Liou%2C+F">Franklin Liou</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Neaton%2C+J+B">Jeffrey B. Neaton</a>, <a href="/search/cond-mat?searchtype=author&query=Weber-Bargioni%2C+A">Alex Weber-Bargioni</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Qiu%2C+Z">Ziqiang Qiu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+G">Guangyu Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Moore%2C+J+E">Joel E. Moore</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2108.03829v2-abstract-short" style="display: inline;"> One-dimensional electron systems (1DESs) exhibit properties that are fundamentally different from higher-dimensional systems. For example, electron-electron interactions in 1DESs have been predicted to induce Tomonaga-Luttinger liquid behavior. Naturally-occurring grain boundaries in single-layer semiconducting transition metal dichalcogenides provide 1D conducting channels that have been proposed… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.03829v2-abstract-full').style.display = 'inline'; document.getElementById('2108.03829v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2108.03829v2-abstract-full" style="display: none;"> One-dimensional electron systems (1DESs) exhibit properties that are fundamentally different from higher-dimensional systems. For example, electron-electron interactions in 1DESs have been predicted to induce Tomonaga-Luttinger liquid behavior. Naturally-occurring grain boundaries in single-layer semiconducting transition metal dichalcogenides provide 1D conducting channels that have been proposed to host Tomonaga-Luttinger liquids, but charge density wave physics has also been suggested to explain their behavior. Clear identification of the electronic ground state of this system has been hampered by an inability to electrostatically gate such boundaries and thereby tune their charge carrier concentration. Here we present a scanning tunneling microscopy/spectroscopy study of gate-tunable mirror twin boundaries (MTBs) in single-layer 1H-MoSe$_2$ devices. Gating here enables STM spectroscopy to be performed for different MTB electron densities, thus allowing precise characterization of electron-electron interaction effects. Visualization of MTB electronic structure under these conditions allows unambiguous identification of collective density wave excitations having two distinct velocities, in quantitative agreement with the spin-charge separation predicted by finite-length Tomonaga-Luttinger-liquid theory. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2108.03829v2-abstract-full').style.display = 'none'; document.getElementById('2108.03829v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 August, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2021. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2106.10599">arXiv:2106.10599</a> <span> [<a href="https://arxiv.org/pdf/2106.10599">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> </div> <p class="title is-5 mathjax"> Imaging Generalized Wigner Crystal States in a WSe2/WS2 Moir茅 Superlattice </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/cond-mat?searchtype=author&query=Regan%2C+E+C">Emma C. Regan</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+D">Danqing Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">Wenyu Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Yumigeta%2C+K">Kentaro Yumigeta</a>, <a href="/search/cond-mat?searchtype=author&query=Blei%2C+M">Mark Blei</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2106.10599v1-abstract-short" style="display: inline;"> The Wigner crystal state, first predicted by Eugene Wigner in 1934, has fascinated condensed matter physicists for nearly 90 years2-14. Studies of two-dimensional (2D) electron gases first revealed signatures of the Wigner crystal in electrical transport measurements at high magnetic fields2-4. More recently optical spectroscopy has provided evidence of generalized Wigner crystal states in transit… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.10599v1-abstract-full').style.display = 'inline'; document.getElementById('2106.10599v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2106.10599v1-abstract-full" style="display: none;"> The Wigner crystal state, first predicted by Eugene Wigner in 1934, has fascinated condensed matter physicists for nearly 90 years2-14. Studies of two-dimensional (2D) electron gases first revealed signatures of the Wigner crystal in electrical transport measurements at high magnetic fields2-4. More recently optical spectroscopy has provided evidence of generalized Wigner crystal states in transition metal dichalcogenide (TMDC) moir茅 superlattices. Direct observation of the 2D Wigner crystal lattice in real space, however, has remained an outstanding challenge. Scanning tunneling microscopy (STM) in principle has sufficient spatial resolution to image a Wigner crystal, but conventional STM measurements can potentially alter fragile Wigner crystal states in the process of measurement. Here we demonstrate real-space imaging of 2D Wigner crystals in WSe2/WS2 moir茅 heterostructures using a novel non-invasive STM spectroscopy technique. We employ a graphene sensing layer in close proximity to the WSe2/WS2 moir茅 superlattice for Wigner crystal imaging, where local STM tunneling current into the graphene sensing layer is modulated by the underlying electron lattice of the Wigner crystal in the WSe2/WS2 heterostructure. Our measurement directly visualizes different lattice configurations associated with Wigner crystal states at fractional electron fillings of n = 1/3, 1/2, and 2/3, where n is the electron number per site. The n=1/3 and n=2/3 Wigner crystals are observed to exhibit a triangle and a honeycomb lattice, respectively, in order to minimize nearest-neighbor occupations. The n = 1/2 state, on the other hand, spontaneously breaks the original C3 symmetry and forms a stripe structure in real space. Our study lays a solid foundation toward the fundamental understanding of rich Wigner crystal states in WSe2/WS2 moir茅 heterostructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2106.10599v1-abstract-full').style.display = 'none'; document.getElementById('2106.10599v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 19 June, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2102.09986">arXiv:2102.09986</a> <span> [<a href="https://arxiv.org/pdf/2102.09986">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-021-01324-x">10.1038/s41567-021-01324-x <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging local discharge cascades for correlated electrons in WS2/WSe2 moir茅 superlattices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Xie%2C+J">Jingxu Xie</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+X">Xinyu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Regan%2C+E">Emma Regan</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+D">Danqing Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">Wenyu Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Yumigeta%2C+K">Kentaro Yumigeta</a>, <a href="/search/cond-mat?searchtype=author&query=Blei%2C+M">Mark Blei</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2102.09986v1-abstract-short" style="display: inline;"> Transition metal dichalcogenide (TMD) moir茅 heterostructures provide an ideal platform to explore the extended Hubbard model1 where long-range Coulomb interactions play a critical role in determining strongly correlated electron states. This has led to experimental observations of Mott insulator states at half filling2-4 as well as a variety of extended Wigner crystal states at different fractiona… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.09986v1-abstract-full').style.display = 'inline'; document.getElementById('2102.09986v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2102.09986v1-abstract-full" style="display: none;"> Transition metal dichalcogenide (TMD) moir茅 heterostructures provide an ideal platform to explore the extended Hubbard model1 where long-range Coulomb interactions play a critical role in determining strongly correlated electron states. This has led to experimental observations of Mott insulator states at half filling2-4 as well as a variety of extended Wigner crystal states at different fractional fillings5-9. Microscopic understanding of these emerging quantum phases, however, is still lacking. Here we describe a novel scanning tunneling microscopy (STM) technique for local sensing and manipulation of correlated electrons in a gated WS2/WSe2 moir茅 superlattice that enables experimental extraction of fundamental extended Hubbard model parameters. We demonstrate that the charge state of local moir茅 sites can be imaged by their influence on STM tunneling current, analogous to the charge-sensing mechanism in a single-electron transistor. In addition to imaging, we are also able to manipulate the charge state of correlated electrons. Discharge cascades of correlated electrons in the moir茅 superlattice are locally induced by ramping the STM bias, thus enabling the nearest-neighbor Coulomb interaction (UNN) to be estimated. 2D mapping of the moir茅 electron charge states also enables us to determine onsite energy fluctuations at different moir茅 sites. Our technique should be broadly applicable to many semiconductor moir茅 systems, offering a powerful new tool for microscopic characterization and control of strongly correlated states in moir茅 superlattices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2102.09986v1-abstract-full').style.display = 'none'; document.getElementById('2102.09986v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 February, 2021; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2021. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.10075">arXiv:2012.10075</a> <span> [<a href="https://arxiv.org/pdf/2012.10075">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.1c03699">10.1021/acs.nanolett.1c03699 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Tunable ferromagnetism at non-integer filling of a moir茅 superlattice </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+G">Guorui Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Sharpe%2C+A+L">Aaron L. Sharpe</a>, <a href="/search/cond-mat?searchtype=author&query=Fox%2C+E+J">Eli J. Fox</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+S">Shaoxin Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Lyu%2C+B">Bosai Lyu</a>, <a href="/search/cond-mat?searchtype=author&query=Jiang%2C+L">Lili Jiang</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Kastner%2C+M+A">M. A. Kastner</a>, <a href="/search/cond-mat?searchtype=author&query=Shi%2C+Z">Zhiwen Shi</a>, <a href="/search/cond-mat?searchtype=author&query=Goldhaber-Gordon%2C+D">David Goldhaber-Gordon</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Y">Yuanbo Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.10075v1-abstract-short" style="display: inline;"> The flat bands resulting from moir茅 superlattices in magic-angle twisted bilayer graphene (MATBG) and ABC-trilayer graphene aligned with hexagonal boron nitride (ABC-TLG/hBN) have been shown to give rise to fascinating correlated electron phenomena such as correlated insulators and superconductivity. More recently, orbital magnetism associated with correlated Chern insulators was found in this cla… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10075v1-abstract-full').style.display = 'inline'; document.getElementById('2012.10075v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.10075v1-abstract-full" style="display: none;"> The flat bands resulting from moir茅 superlattices in magic-angle twisted bilayer graphene (MATBG) and ABC-trilayer graphene aligned with hexagonal boron nitride (ABC-TLG/hBN) have been shown to give rise to fascinating correlated electron phenomena such as correlated insulators and superconductivity. More recently, orbital magnetism associated with correlated Chern insulators was found in this class of layered structures centered at integer multiples of n0, the density corresponding to one electron per moir茅 superlattice unit cell. Here we report the experimental observation of ferromagnetism at fractional filling of a flat Chern band in an ABC-TLG/hBN moir茅superlattice. The ferromagnetic state exhibits prominent ferromagnetic hysteresis behavior with large anomalous Hall resistivity in a broad region of densities, centered in the valence miniband at n = -2.3 n0. This ferromagnetism depends very sensitively on the control parameters in the moir茅 system: not only the magnitude of the anomalous Hall signal, but also the sign of the hysteretic ferromagnetic response can be modulated by tuning the carrier density and displacement field. Our discovery of electrically tunable ferromagnetism in a moir茅 Chern band at non-integer filling highlights the opportunities for exploring new correlated ferromagnetic states in moir茅 heterostructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.10075v1-abstract-full').style.display = 'none'; document.getElementById('2012.10075v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 18 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">12 pages, 4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2012.00494">arXiv:2012.00494</a> <span> [<a href="https://arxiv.org/pdf/2012.00494">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/jacs.6b05203">10.1021/jacs.6b05203 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Non-Covalent Dimerization after Enediyne Cyclization on Au(111) </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=de+Oteyza%2C+D+G">Dimas G. de Oteyza</a>, <a href="/search/cond-mat?searchtype=author&query=Paz%2C+A+P">Alejandro P茅rez Paz</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yen-Chia Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Pedramrazi%2C+Z">Zahra Pedramrazi</a>, <a href="/search/cond-mat?searchtype=author&query=Riss%2C+A">Alexander Riss</a>, <a href="/search/cond-mat?searchtype=author&query=Wickenburg%2C+S">Sebastian Wickenburg</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Rubio%2C+A">Angel Rubio</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2012.00494v1-abstract-short" style="display: inline;"> We investigate the thermally-induced cyclization of 1,2 - bis(2 - phenylethynyl)benzene on Au(111) using scanning tunneling microscopy and computer simulations. Cyclization of sterically hindered enediynes is known to proceed via two competing mechanisms in solution: a classic C1 - C6 or a C1 - C5 cyclization pathway. On Au(111) we find that the C1 - C5 cyclization is suppressed and that the C1 -… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00494v1-abstract-full').style.display = 'inline'; document.getElementById('2012.00494v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2012.00494v1-abstract-full" style="display: none;"> We investigate the thermally-induced cyclization of 1,2 - bis(2 - phenylethynyl)benzene on Au(111) using scanning tunneling microscopy and computer simulations. Cyclization of sterically hindered enediynes is known to proceed via two competing mechanisms in solution: a classic C1 - C6 or a C1 - C5 cyclization pathway. On Au(111) we find that the C1 - C5 cyclization is suppressed and that the C1 - C6 cyclization yields a highly strained bicyclic olefin whose surface chemistry was hitherto unknown. The C1 - C6 product self-assembles into discrete non-covalently bound dimers on the surface. The reaction mechanism and driving forces behind non-covalent association are discussed in light of density functional theory calculations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2012.00494v1-abstract-full').style.display = 'none'; document.getElementById('2012.00494v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 December, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Am. Chem. Soc. 2016, 138, 10963-10967 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2009.07379">arXiv:2009.07379</a> <span> [<a href="https://arxiv.org/pdf/2009.07379">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-021-01321-0">10.1038/s41567-021-01321-0 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging spinon density modulations in a 2D quantum spin liquid </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+J">Jinwoong Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+R">Ryan Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+M">Meng Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Liou%2C+F">Franklin Liou</a>, <a href="/search/cond-mat?searchtype=author&query=Jia%2C+C">Caihong Jia</a>, <a href="/search/cond-mat?searchtype=author&query=Aikawa%2C+A">Andrew Aikawa</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Choi%2C+Y">Yongseong Choi</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+P+A">Patrick A. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2009.07379v1-abstract-short" style="display: inline;"> Two-dimensional triangular-lattice antiferromagnets are predicted under some conditions to exhibit a quantum spin liquid ground state whose low-energy behavior is described by a spinon Fermi surface. Directly imaging the resulting spinons, however, is difficult due to their fractional, chargeless nature. Here we use scanning tunneling spectroscopy to image spinon density modulations arising from a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.07379v1-abstract-full').style.display = 'inline'; document.getElementById('2009.07379v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.07379v1-abstract-full" style="display: none;"> Two-dimensional triangular-lattice antiferromagnets are predicted under some conditions to exhibit a quantum spin liquid ground state whose low-energy behavior is described by a spinon Fermi surface. Directly imaging the resulting spinons, however, is difficult due to their fractional, chargeless nature. Here we use scanning tunneling spectroscopy to image spinon density modulations arising from a spinon Fermi surface instability in single-layer 1T-TaSe$_2$, a two-dimensional Mott insulator. We first demonstrate the existence of localized spins arranged on a triangular lattice in single-layer 1T-TaSe$_2$ by contacting it to a metallic 1H-TaSe$_2$ layer and measuring the Kondo effect. Subsequent spectroscopic imaging of isolated, single-layer 1T-TaSe$_2$ reveals long-wavelength modulations at Hubbard band energies that reflect spinon density modulations. This allows direct experimental measurement of the spinon Fermi wavevector, in good agreement with theoretical predictions for a 2D quantum spin liquid. These results establish single-layer 1T-TaSe$_2$ as a new platform for studying novel two-dimensional quantum-spin-liquid phenomena. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.07379v1-abstract-full').style.display = 'none'; document.getElementById('2009.07379v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.07536">arXiv:2008.07536</a> <span> [<a href="https://arxiv.org/pdf/2008.07536">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-021-22711-1">10.1038/s41467-021-22711-1 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Visualizing delocalized correlated electronic states in twisted double bilayer graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Canxun Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+T">Tiancong Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/cond-mat?searchtype=author&query=Yang%2C+B">Birui Yang</a>, <a href="/search/cond-mat?searchtype=author&query=Herbig%2C+C">Charlotte Herbig</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+X">Xuehao Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Cabrini%2C+S">Stefano Cabrini</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Zaletel%2C+M+P">Michael P. Zaletel</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2008.07536v2-abstract-short" style="display: inline;"> The discovery of interaction-driven insulating and superconducting phases in moir茅 van der Waals heterostructures has sparked considerable interest in understanding the novel correlated physics of these systems. While a significant number of studies have focused on twisted bilayer graphene, correlated insulating states and a superconductivity-like transition up to 12 K have been reported in recent… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.07536v2-abstract-full').style.display = 'inline'; document.getElementById('2008.07536v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.07536v2-abstract-full" style="display: none;"> The discovery of interaction-driven insulating and superconducting phases in moir茅 van der Waals heterostructures has sparked considerable interest in understanding the novel correlated physics of these systems. While a significant number of studies have focused on twisted bilayer graphene, correlated insulating states and a superconductivity-like transition up to 12 K have been reported in recent transport measurements of twisted double bilayer graphene. Here we present a scanning tunneling microscopy and spectroscopy study of gate-tunable twisted double bilayer graphene devices. We observe splitting of the van Hove singularity peak by ~20 meV at half-filling of the conduction flat band, with a corresponding reduction of the local density of states at the Fermi level. By mapping the tunneling differential conductance we show that this correlated system exhibits energetically split states that are spatially delocalized throughout the different regions in the moir茅 unit cell, inconsistent with order originating solely from onsite Coulomb repulsion within strongly-localized orbitals. We have performed self-consistent Hartree-Fock calculations that suggest exchange-driven spontaneous symmetry breaking in the degenerate conduction flat band is the origin of the observed correlated state. Our results provide new insight into the nature of electron-electron interactions in twisted double bilayer graphene and related moir茅 systems. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.07536v2-abstract-full').style.display = 'none'; document.getElementById('2008.07536v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 22 March, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">24 pages, 5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 12, 2516 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2007.06113">arXiv:2007.06113</a> <span> [<a href="https://arxiv.org/pdf/2007.06113">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41563-021-00923-6">10.1038/s41563-021-00923-6 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging moir茅 flat bands in 3D reconstructed WSe2/WS2 superlattices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Li%2C+H">Hongyuan Li</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+S">Shaowei Li</a>, <a href="/search/cond-mat?searchtype=author&query=Naik%2C+M+H">Mit H. Naik</a>, <a href="/search/cond-mat?searchtype=author&query=Xie%2C+J">Jingxu Xie</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+X">Xinyu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+J">Jiayin Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Regan%2C+E">Emma Regan</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+D">Danqing Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">Wenyu Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+S">Sihan Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Yumigeta%2C+K">Kentaro Yumigeta</a>, <a href="/search/cond-mat?searchtype=author&query=Blei%2C+M">Mark Blei</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="2007.06113v1-abstract-short" style="display: inline;"> Moir茅 superlattices in transition metal dichalcogenide (TMD) heterostructures can host novel correlated quantum phenomena due to the interplay of narrow moir茅 flat bands and strong, long-range Coulomb interactions1-5. However, microscopic knowledge of the atomically-reconstructed moir茅 superlattice and resulting flat bands is still lacking, which is critical for fundamental understanding and contr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.06113v1-abstract-full').style.display = 'inline'; document.getElementById('2007.06113v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2007.06113v1-abstract-full" style="display: none;"> Moir茅 superlattices in transition metal dichalcogenide (TMD) heterostructures can host novel correlated quantum phenomena due to the interplay of narrow moir茅 flat bands and strong, long-range Coulomb interactions1-5. However, microscopic knowledge of the atomically-reconstructed moir茅 superlattice and resulting flat bands is still lacking, which is critical for fundamental understanding and control of the correlated moir茅 phenomena. Here we quantitatively study the moir茅 flat bands in three-dimensional (3D) reconstructed WSe2/WS2 moir茅 superlattices by comparing scanning tunneling spectroscopy (STS) of high quality exfoliated TMD heterostructure devices with ab initio simulations of TMD moir茅 superlattices. A strong 3D buckling reconstruction accompanied by large in-plane strain redistribution is identified in our WSe2/WS2 moir茅 heterostructures. STS imaging demonstrates that this results in a remarkably narrow and highly localized K-point moir茅 flat band at the valence band edge of the heterostructure. A series of moir茅 flat bands are observed at different energies that exhibit varying degrees of localization. Our observations contradict previous simplified theoretical models but agree quantitatively with ab initio simulations that fully capture the 3D structural reconstruction. Here the strain redistribution and 3D buckling dominate the effective moir茅 potential and result in moir茅 flat bands at the Brillouin zone K points. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2007.06113v1-abstract-full').style.display = 'none'; document.getElementById('2007.06113v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 12 July, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.09055">arXiv:1911.09055</a> <span> [<a href="https://arxiv.org/pdf/1911.09055">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Instrumentation and Detectors">physics.ins-det</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/ncomms13704">10.1038/ncomms13704 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging electric field dynamics with graphene optoelectronics </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Horng%2C+J">Jason Horng</a>, <a href="/search/cond-mat?searchtype=author&query=Balch%2C+H+B">Halleh B. Balch</a>, <a href="/search/cond-mat?searchtype=author&query=McGuire%2C+A+F">Allister F. McGuire</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Forrester%2C+P+R">Patrick R. Forrester</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Cui%2C+B">Bianxiao Cui</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.09055v1-abstract-short" style="display: inline;"> The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric field… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.09055v1-abstract-full').style.display = 'inline'; document.getElementById('1911.09055v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.09055v1-abstract-full" style="display: none;"> The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.09055v1-abstract-full').style.display = 'none'; document.getElementById('1911.09055v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">9 pages, 5 figures, supplement can be found at 10.1038/ncomms13704</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat Commun 7, 13704 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1911.00601">arXiv:1911.00601</a> <span> [<a href="https://arxiv.org/pdf/1911.00601">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Chemical Physics">physics.chem-ph</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1126/science.aay3588">10.1126/science.aay3588 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Inducing Metallicity in Graphene Nanoribbons via Zero-Mode Superlattices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Rizzo%2C+D+J">Daniel J. Rizzo</a>, <a href="/search/cond-mat?searchtype=author&query=Veber%2C+G">Gregory Veber</a>, <a href="/search/cond-mat?searchtype=author&query=Jiang%2C+J">Jingwei Jiang</a>, <a href="/search/cond-mat?searchtype=author&query=McCurdy%2C+R">Ryan McCurdy</a>, <a href="/search/cond-mat?searchtype=author&query=Cao%2C+T">Ting Cao</a>, <a href="/search/cond-mat?searchtype=author&query=Bronner%2C+C">Christopher Bronner</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+T">Ting Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1911.00601v1-abstract-short" style="display: inline;"> The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) is a significant challenge since lateral quantum confinement and many-electron interactions tend to induce electronic band gaps when graphene is patterned at nanometer length scales. Recent developments in bottom-up synthesis have enabled the design and characterization of atomically-precise GNRs, but strategies fo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.00601v1-abstract-full').style.display = 'inline'; document.getElementById('1911.00601v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1911.00601v1-abstract-full" style="display: none;"> The design and fabrication of robust metallic states in graphene nanoribbons (GNRs) is a significant challenge since lateral quantum confinement and many-electron interactions tend to induce electronic band gaps when graphene is patterned at nanometer length scales. Recent developments in bottom-up synthesis have enabled the design and characterization of atomically-precise GNRs, but strategies for realizing GNR metallicity have been elusive. Here we demonstrate a general technique for inducing metallicity in GNRs by inserting a symmetric superlattice of zero-energy modes into otherwise semiconducting GNRs. We verify the resulting metallicity using scanning tunneling spectroscopy as well as first-principles density-functional theory and tight binding calculations. Our results reveal that the metallic bandwidth in GNRs can be tuned over a wide range by controlling the overlap of zero-mode wavefunctions through intentional sublattice symmetry-breaking. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1911.00601v1-abstract-full').style.display = 'none'; document.getElementById('1911.00601v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 1 November, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">The first three authors listed contributed equally</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1904.11010">arXiv:1904.11010</a> <span> [<a href="https://arxiv.org/pdf/1904.11010">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Strongly Correlated Electrons">cond-mat.str-el</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41567-019-0744-9">10.1038/s41567-019-0744-9 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Ruan%2C+W">Wei Ruan</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+M">Meng Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+R">Ryan Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Liou%2C+F">Franklin Liou</a>, <a href="/search/cond-mat?searchtype=author&query=Jia%2C+C">Caihong Jia</a>, <a href="/search/cond-mat?searchtype=author&query=Albertini%2C+O+R">Oliver R. Albertini</a>, <a href="/search/cond-mat?searchtype=author&query=Xiong%2C+H">Hongyu Xiong</a>, <a href="/search/cond-mat?searchtype=author&query=Jia%2C+T">Tao Jia</a>, <a href="/search/cond-mat?searchtype=author&query=Liu%2C+Z">Zhi Liu</a>, <a href="/search/cond-mat?searchtype=author&query=Sobota%2C+J+A">Jonathan A. Sobota</a>, <a href="/search/cond-mat?searchtype=author&query=Liu%2C+A+Y">Amy Y. Liu</a>, <a href="/search/cond-mat?searchtype=author&query=Moore%2C+J+E">Joel E. Moore</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1904.11010v2-abstract-short" style="display: inline;"> Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.11010v2-abstract-full').style.display = 'inline'; document.getElementById('1904.11010v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1904.11010v2-abstract-full" style="display: none;"> Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunneling microscopy and angle-resolved photoemission. Our combined experimental and theoretical study indicates that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by novel orbital texture. Inclusion of interlayer coupling weakens the insulating phase in 1T-TaSe2, as seen by strong reduction of its energy gap and quenching of its correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. Our results establish single-layer 1T-TaSe2 as a useful new platform for investigating strong correlation physics in two dimensions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1904.11010v2-abstract-full').style.display = 'none'; document.getElementById('1904.11010v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 May, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 24 April, 2019; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 2019. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 16, 218-224 (2020) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1812.03663">arXiv:1812.03663</a> <span> [<a href="https://arxiv.org/pdf/1812.03663">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-019-08371-2">10.1038/s41467-019-08371-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electrons imitating light: Frustrated supercritical collapse in charged arrays on graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lu%2C+J">Jiong Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Tatan%2C+A+N">Alpin N. Tatan</a>, <a href="/search/cond-mat?searchtype=author&query=Wickenburg%2C+S">Sebastian Wickenburg</a>, <a href="/search/cond-mat?searchtype=author&query=Omrani%2C+A+A">Arash A. Omrani</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Riss%2C+A">Alexander Riss</a>, <a href="/search/cond-mat?searchtype=author&query=Piatti%2C+E">Erik Piatti</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Pereira%2C+V+M">Vitor M. Pereira</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1812.03663v1-abstract-short" style="display: inline;"> The photon-like electronic dispersion of graphene bestows its charge carriers with unusual confinement properties that depend strongly on the geometry and strength of the surrounding potential. Here we report bottom-up synthesis of atomically-precise one-dimensional (1D) arrays of point charges aimed at exploring supercritical confinement of carriers in graphene for new geometries. The arrays were… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.03663v1-abstract-full').style.display = 'inline'; document.getElementById('1812.03663v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1812.03663v1-abstract-full" style="display: none;"> The photon-like electronic dispersion of graphene bestows its charge carriers with unusual confinement properties that depend strongly on the geometry and strength of the surrounding potential. Here we report bottom-up synthesis of atomically-precise one-dimensional (1D) arrays of point charges aimed at exploring supercritical confinement of carriers in graphene for new geometries. The arrays were synthesized by arranging F4TCNQ molecules into a 1D lattice on back-gated graphene devices, allowing precise tuning of both the molecular charge state and the array periodicity. Dilute arrays of ionized F4TCNQ molecules are seen to behave like isolated subcritical charges but dense arrays show emergent supercriticality. In contrast to compact supercritical clusters, extended 1D charge arrays exhibit both supercritical and subcritical characteristics and belong to a new physical regime termed frustrated supercritical collapse. Here carriers in the far-field are attracted by a supercritical charge distribution, but have their fall to the center frustrated by subcritical potentials in the near-field, similar to the trapping of light by a dense cluster of stars in general relativity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1812.03663v1-abstract-full').style.display = 'none'; document.getElementById('1812.03663v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 10 December, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 10, 477 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.10623">arXiv:1810.10623</a> <span> [<a href="https://arxiv.org/pdf/1810.10623">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.98.155436">10.1103/PhysRevB.98.155436 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Microscopy of hydrogen and hydrogen-vacancy defect structures on graphene devices </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Y">Yang Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Jin%2C+W">Wuwei Jin</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Bostwick%2C+A">Aaron Bostwick</a>, <a href="/search/cond-mat?searchtype=author&query=Rotenberg%2C+E">Eli Rotenberg</a>, <a href="/search/cond-mat?searchtype=author&query=Kawakami%2C+R+K">Roland K. Kawakami</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Mostofi%2C+A+A">Arash A. Mostofi</a>, <a href="/search/cond-mat?searchtype=author&query=Lischner%2C+J">Johannes Lischner</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.10623v1-abstract-short" style="display: inline;"> We have used scanning tunneling microscopy (STM) to investigate two types of hydrogen defect structures on monolayer graphene supported by hexagonal boron nitride (h-BN) in a gated field-effect transistor configuration. The first H-defect type is created by bombarding graphene with 1-keV ionized hydrogen and is identified as two hydrogen atoms bonded to a graphene vacancy via comparison of experim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.10623v1-abstract-full').style.display = 'inline'; document.getElementById('1810.10623v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.10623v1-abstract-full" style="display: none;"> We have used scanning tunneling microscopy (STM) to investigate two types of hydrogen defect structures on monolayer graphene supported by hexagonal boron nitride (h-BN) in a gated field-effect transistor configuration. The first H-defect type is created by bombarding graphene with 1-keV ionized hydrogen and is identified as two hydrogen atoms bonded to a graphene vacancy via comparison of experimental data to first-principles calculations. The second type of H defect is identified as dimerized hydrogen and is created by depositing atomic hydrogen having only thermal energy onto a graphene surface. Scanning tunneling spectroscopy (STS) measurements reveal that hydrogen dimers formed in this way open a new elastic channel in the tunneling conductance between an STM tip and graphene. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.10623v1-abstract-full').style.display = 'none'; document.getElementById('1810.10623v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 24 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">5 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 98, 155436 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.05285">arXiv:1810.05285</a> <span> [<a href="https://arxiv.org/pdf/1810.05285">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Simulating the nanomechanical response of cyclooctatetraene molecules on a graphene device </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Oh%2C+S">Sehoon Oh</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Cohen%2C+M+L">Marvin L. Cohen</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.05285v1-abstract-short" style="display: inline;"> We investigate the atomic and electronic structures of cyclooctatetraene (COT) molecules on graphene and analyze their dependence on external gate voltage using first-principles calculations. The external gate voltage is simulated by adding or removing electrons using density functional theory (DFT) calculations. This allows us to investigate how changes in carrier density modify the molecular sha… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.05285v1-abstract-full').style.display = 'inline'; document.getElementById('1810.05285v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.05285v1-abstract-full" style="display: none;"> We investigate the atomic and electronic structures of cyclooctatetraene (COT) molecules on graphene and analyze their dependence on external gate voltage using first-principles calculations. The external gate voltage is simulated by adding or removing electrons using density functional theory (DFT) calculations. This allows us to investigate how changes in carrier density modify the molecular shape, orientation, adsorption site, diffusion barrier, and diffusion path. For increased hole doping COT molecules gradually change their shape to a more flattened conformation and the distance between the molecules and graphene increases while the diffusion barrier drastically decreases. For increased electron doping an abrupt transition to a planar conformation at a carrier density of -8$\times$10$^{13}$ e/cm$^2$ is observed. These calculations imply that the shape and mobility of adsorbed COT molecules can be controlled by externally gating graphene devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.05285v1-abstract-full').style.display = 'none'; document.getElementById('1810.05285v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1810.03364">arXiv:1810.03364</a> <span> [<a href="https://arxiv.org/pdf/1810.03364">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-019-11342-2">10.1038/s41467-019-11342-2 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Identifying substitutional oxygen as a prolific point defect in monolayer transition metal dichalcogenides with experiment and theory </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barja%2C+S">Sara Barja</a>, <a href="/search/cond-mat?searchtype=author&query=Refaely-Abramson%2C+S">Sivan Refaely-Abramson</a>, <a href="/search/cond-mat?searchtype=author&query=Schuler%2C+B">Bruno Schuler</a>, <a href="/search/cond-mat?searchtype=author&query=Qiu%2C+D+Y">Diana Y. Qiu</a>, <a href="/search/cond-mat?searchtype=author&query=Pulkin%2C+A">Artem Pulkin</a>, <a href="/search/cond-mat?searchtype=author&query=Wickenburg%2C+S">Sebastian Wickenburg</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Ugeda%2C+M+M">Miguel M. Ugeda</a>, <a href="/search/cond-mat?searchtype=author&query=Kastl%2C+C">Christoph Kastl</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+C">Christopher Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Schwartzberg%2C+A">Adam Schwartzberg</a>, <a href="/search/cond-mat?searchtype=author&query=Aloni%2C+S">Shaul Aloni</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Ogletree%2C+D+F">D. Frank Ogletree</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Yazyev%2C+O+V">Oleg V. Yazyev</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Neaton%2C+J+B">Jeffrey B. Neaton</a>, <a href="/search/cond-mat?searchtype=author&query=Weber-Bargioni%2C+A">Alexander Weber-Bargioni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1810.03364v2-abstract-short" style="display: inline;"> Chalcogen vacancies are considered to be the most abundant point defects in two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors, and predicted to result in deep in-gap states (IGS). As a result, important features in the optical response of 2D-TMDs have typically been attributed to chalcogen vacancies, with indirect support from Transmission Electron Microscopy (TEM) and Scan… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.03364v2-abstract-full').style.display = 'inline'; document.getElementById('1810.03364v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1810.03364v2-abstract-full" style="display: none;"> Chalcogen vacancies are considered to be the most abundant point defects in two-dimensional (2D) transition-metal dichalcogenide (TMD) semiconductors, and predicted to result in deep in-gap states (IGS). As a result, important features in the optical response of 2D-TMDs have typically been attributed to chalcogen vacancies, with indirect support from Transmission Electron Microscopy (TEM) and Scanning Tunneling Microscopy (STM) images. However, TEM imaging measurements do not provide direct access to the electronic structure of individual defects; and while Scanning Tunneling Spectroscopy (STS) is a direct probe of local electronic structure, the interpretation of the chemical nature of atomically-resolved STM images of point defects in 2D-TMDs can be ambiguous. As a result, the assignment of point defects as vacancies or substitutional atoms of different kinds in 2D-TMDs, and their influence on their electronic properties, has been inconsistent and lacks consensus. Here, we combine low-temperature non-contact atomic force microscopy (nc-AFM), STS, and state-of-the-art ab initio density functional theory (DFT) and GW calculations to determine both the structure and electronic properties of the most abundant individual chalcogen-site defects common to 2D-TMDs. Surprisingly, we observe no IGS for any of the chalcogen defects probed. Our results and analysis strongly suggest that the common chalcogen defects in our 2D-TMDs, prepared and measured in standard environments, are substitutional oxygen rather than vacancies. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1810.03364v2-abstract-full').style.display = 'none'; document.getElementById('1810.03364v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 6 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 8 October, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nat Commun 10, 3382 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1809.05209">arXiv:1809.05209</a> <span> [<a href="https://arxiv.org/pdf/1809.05209">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.8b01972">10.1021/acs.nanolett.8b01972 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Visualization and Control of Single Electron Charging in Bilayer Graphene Quantum Dots </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Velasco%2C+J">Jairo Velasco Jr.</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Juwon Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Costello%2C+J">Joseph Costello</a>, <a href="/search/cond-mat?searchtype=author&query=Umeda%2C+T">Torben Umeda</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1809.05209v1-abstract-short" style="display: inline;"> Graphene p-n junctions provide an ideal platform for investigating novel behavior at the boundary between electronics and optics that arise from massless Dirac fermions, such as whispering gallery modes and Veselago lensing. Bilayer graphene also hosts Dirac fermions, but they differ from single-layer graphene charge carriers because they are massive, can be gapped by an applied perpendicular elec… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.05209v1-abstract-full').style.display = 'inline'; document.getElementById('1809.05209v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1809.05209v1-abstract-full" style="display: none;"> Graphene p-n junctions provide an ideal platform for investigating novel behavior at the boundary between electronics and optics that arise from massless Dirac fermions, such as whispering gallery modes and Veselago lensing. Bilayer graphene also hosts Dirac fermions, but they differ from single-layer graphene charge carriers because they are massive, can be gapped by an applied perpendicular electric field, and have very different pseudospin selection rules across a p-n junction. Novel phenomena predicted for these massive Dirac fermions at p-n junctions include anti-Klein tunneling, oscillatory Zener tunneling, and electron cloaked states. Despite these predictions there has been little experimental focus on the microscopic spatial behavior of massive Dirac fermions in the presence of p-n junctions. Here we report the experimental manipulation and characterization of massive Dirac fermions within bilayer graphene quantum dots defined by circular p-n junctions through the use of scanning tunneling microscopy-based (STM) methods. Our p-n junctions are created via a flexible technique that enables realization of exposed quantum dots in bilayer graphene/hBN heterostructures. These quantum dots exhibit sharp spectroscopic resonances that disperse in energy as a function of applied gate voltage. Spatial maps of these features show prominent concentric rings with diameters that can be tuned by an electrostatic gate. This behavior is explained by single-electron charging of localized states that arise from the quantum confinement of massive Dirac fermions within our exposed bilayer graphene quantum dots. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1809.05209v1-abstract-full').style.display = 'none'; document.getElementById('1809.05209v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 13 September, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nano Lett., 2018, 18 (8), 5104 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1805.06470">arXiv:1805.06470</a> <span> [<a href="https://arxiv.org/pdf/1805.06470">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41586-018-0376-8">10.1038/s41586-018-0376-8 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Topological Band Engineering of Graphene Nanoribbons </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Rizzo%2C+D+J">Daniel J. Rizzo</a>, <a href="/search/cond-mat?searchtype=author&query=Veber%2C+G">Gregory Veber</a>, <a href="/search/cond-mat?searchtype=author&query=Cao%2C+T">Ting Cao</a>, <a href="/search/cond-mat?searchtype=author&query=Bronner%2C+C">Christopher Bronner</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+T">Ting Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+F">Fangzhou Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Rodriguez%2C+H">Henry Rodriguez</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+S+G+L+M+F">Steven G. Louie Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1805.06470v1-abstract-short" style="display: inline;"> Topological insulators (TIs) are an emerging class of materials that host highly robust in-gap surface/interface states while maintaining an insulating bulk. While most notable scientific advancements in this field have been focused on TIs and related topological crystalline insulators in 2D and 3D, more recent theoretical work has predicted the existence of 1D symmetry-protected topological phase… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.06470v1-abstract-full').style.display = 'inline'; document.getElementById('1805.06470v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1805.06470v1-abstract-full" style="display: none;"> Topological insulators (TIs) are an emerging class of materials that host highly robust in-gap surface/interface states while maintaining an insulating bulk. While most notable scientific advancements in this field have been focused on TIs and related topological crystalline insulators in 2D and 3D, more recent theoretical work has predicted the existence of 1D symmetry-protected topological phases in graphene nanoribbons (GNRs). The topological phase of these laterally-confined, semiconducting strips of graphene is determined by their width, edge shape, and the terminating unit cell, and is characterized by a Z2 invariant (similar to 1D solitonic systems). Interfaces between topologically distinct GNRs characterized by different Z2 are predicted to support half-filled in-gap localized electronic states which can, in principle, be utilized as a tool for material engineering. Here we present the rational design and experimental realization of a topologically-engineered GNR superlattice that hosts a 1D array of such states, thus generating otherwise inaccessible electronic structure. This strategy also enables new end states to be engineered directly into the termini of the 1D GNR superlattice. Atomically-precise topological GNR superlattices were synthesized from molecular precursors on a Au(111) surface under ultra-high vacuum (UHV) conditions and characterized by low temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Our experimental results and first-principles calculations reveal that the frontier band structure of these GNR superlattices is defined purely by the coupling between adjacent topological interface states. This novel manifestation of 1D topological phases presents an entirely new route to band engineering in 1D materials based on precise control of their electronic topology, and is a promising platform for future studies of 1D quantum spin physics. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1805.06470v1-abstract-full').style.display = 'none'; document.getElementById('1805.06470v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 16 May, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Contains main manuscript and supplemental information</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1802.01339">arXiv:1802.01339</a> <span> [<a href="https://arxiv.org/pdf/1802.01339">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/s41467-018-05672-w">10.1038/s41467-018-05672-w <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of Topologically Protected States at Crystalline Phase Boundaries in Single-layer WSe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Ugeda%2C+M+M">Miguel M. Ugeda</a>, <a href="/search/cond-mat?searchtype=author&query=Pulkin%2C+A">Artem Pulkin</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+Q">Quansheng Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Y">Yi Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Pedramrazi%2C+Z">Zahra Pedramrazi</a>, <a href="/search/cond-mat?searchtype=author&query=Mart%C3%ADn-Recio%2C+A">Ana Mart铆n-Recio</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yi Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Yazyev%2C+O+V">Oleg V. Yazyev</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1802.01339v2-abstract-short" style="display: inline;"> Transition metal dichalcogenide (TMD) materials are unique in the wide variety of structural and electronic phases they exhibit in the two-dimensional (2D) single-layer limit. Here we show how such polymorphic flexibility can be used to achieve topological states at highly ordered phase boundaries in a new quantum spin Hall insulator (QSHI), 1T'-WSe2. We observe helical states at the crystallograp… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.01339v2-abstract-full').style.display = 'inline'; document.getElementById('1802.01339v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1802.01339v2-abstract-full" style="display: none;"> Transition metal dichalcogenide (TMD) materials are unique in the wide variety of structural and electronic phases they exhibit in the two-dimensional (2D) single-layer limit. Here we show how such polymorphic flexibility can be used to achieve topological states at highly ordered phase boundaries in a new quantum spin Hall insulator (QSHI), 1T'-WSe2. We observe helical states at the crystallographically-aligned interface between quantum a spin Hall insulating domain of 1T'-WSe2 and a semiconducting domain of 1H-WSe2 in contiguous single layers grown using molecular beam epitaxy (MBE). The QSHI nature of single-layer 1T'-WSe2 was verified using ARPES to determine band inversion around a 120 meV energy gap, as well as STM spectroscopy to directly image helical edge-state formation. Using this new edge-state geometry we are able to directly confirm the predicted penetration depth of a helical interface state into the 2D bulk of a QSHI for a well-specified crystallographic direction. The clean, well-ordered topological/trivial interfaces observed here create new opportunities for testing predictions of the microscopic behavior of topologically protected boundary states without the complication of structural disorder. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1802.01339v2-abstract-full').style.display = 'none'; document.getElementById('1802.01339v2-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 7 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 5 February, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2018. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">https://www.nature.com/articles/s41467-018-05672-w</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Communications 9, 3401 (2018) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1711.05771">arXiv:1711.05771</a> <span> [<a href="https://arxiv.org/pdf/1711.05771">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> </div> <p class="title is-5 mathjax"> Hierarchical On-Surface Synthesis of Deterministic Graphene Nanoribbon Heterojunctions </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Bronner%2C+C">Christopher Bronner</a>, <a href="/search/cond-mat?searchtype=author&query=Durr%2C+R+A">Rebecca A. Durr</a>, <a href="/search/cond-mat?searchtype=author&query=Rizzo%2C+D+J">Daniel J. Rizzo</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+Y">Yea-Lee Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Marangoni%2C+T">Tomas Marangoni</a>, <a href="/search/cond-mat?searchtype=author&query=Kalayjian%2C+A+M">Alin Miksi Kalayjian</a>, <a href="/search/cond-mat?searchtype=author&query=Rodriguez%2C+H">Henry Rodriguez</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+W">William Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Louie%2C+S+G">Steven G. Louie</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1711.05771v1-abstract-short" style="display: inline;"> Bottom-up graphene nanoribbon (GNR) heterojunctions are nanoscale strips of graphene whose electronic structure abruptly changes across a covalently bonded interface. Their rational design offers opportunities for profound technological advancements enabled by their extraordinary structural and electronic properties. Thus far the most critical aspect of their synthesis, the control over sequence a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.05771v1-abstract-full').style.display = 'inline'; document.getElementById('1711.05771v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1711.05771v1-abstract-full" style="display: none;"> Bottom-up graphene nanoribbon (GNR) heterojunctions are nanoscale strips of graphene whose electronic structure abruptly changes across a covalently bonded interface. Their rational design offers opportunities for profound technological advancements enabled by their extraordinary structural and electronic properties. Thus far the most critical aspect of their synthesis, the control over sequence and position of heterojunctions along the length of a ribbon, has been plagued by randomness in monomer sequences emerging from step-growth copolymerization of distinct monomers. All bottom-up GNR heterojunction structures created so far have exhibited random sequences of heterojunctions and, while useful for fundamental scientific studies, are difficult to incorporate into functional nanodevices as a result. Here we describe a new hierarchical fabrication strategy that allows deterministic growth of bottom-up GNRs that preferentially exhibit a single heterojunction interface rather than a random statistical sequence of junctions along the ribbon. Such heterojunctions provide a viable new platform that could be directly used in functional GNR-based device applications at the molecular scale. Our hierarchical GNR fabrication strategy is based on differences in the dissociation energies of C-Br and C-I bonds that allow control over the growth sequence of the block-copolymers from which GNRs are formed, and consequently yields a significantly higher proportion of single-junction GNR heterostructures. Scanning tunnelling spectroscopy and density functional theory calculations confirm that hierarchically-grown heterojunctions between chevron GNR (cGNR) and binaphthyl-cGNR segments exhibit straddling Type I band alignment in structures that are only one atomic layer thick and 3 nm in width. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1711.05771v1-abstract-full').style.display = 'none'; document.getElementById('1711.05771v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Contains main manuscript (p. 1-16) and supplementary information (p. 17-50)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1705.06077">arXiv:1705.06077</a> <span> [<a href="https://arxiv.org/pdf/1705.06077">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1103/PhysRevB.95.205419">10.1103/PhysRevB.95.205419 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Spatially resolving density-dependent screening around a single charged atom in graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Corsetti%2C+F">Fabiano Corsetti</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Y">Yang Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Brar%2C+V+W">Victor W. Brar</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+Q">Qiong Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Kawakami%2C+R+K">Roland K. Kawakami</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Mostofi%2C+A+A">Arash A. Mostofi</a>, <a href="/search/cond-mat?searchtype=author&query=Lischner%2C+J">Johannes Lischner</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1705.06077v1-abstract-short" style="display: inline;"> Electrons in two-dimensional graphene sheets behave as interacting chiral Dirac fermions and have unique screening properties due to their symmetry and reduced dimensionality. By using a combination of scanning tunneling spectroscopy (STM/STS) measurements and theoretical modeling we have characterized how graphene's massless charge carriers screen individual charged calcium atoms. A back-gated gr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1705.06077v1-abstract-full').style.display = 'inline'; document.getElementById('1705.06077v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1705.06077v1-abstract-full" style="display: none;"> Electrons in two-dimensional graphene sheets behave as interacting chiral Dirac fermions and have unique screening properties due to their symmetry and reduced dimensionality. By using a combination of scanning tunneling spectroscopy (STM/STS) measurements and theoretical modeling we have characterized how graphene's massless charge carriers screen individual charged calcium atoms. A back-gated graphene device configuration has allowed us to directly visualize how the screening length for this system can be tuned with carrier density. Our results provide insight into electron-impurity and electron-electron interactions in a relativistic setting with important consequences for other graphene-based electronic devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1705.06077v1-abstract-full').style.display = 'none'; document.getElementById('1705.06077v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 May, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B 95, 205419 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.09191">arXiv:1703.09191</a> <span> [<a href="https://arxiv.org/pdf/1703.09191">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Iodine versus Bromine Functionalization for Bottom-Up Graphene Nanoribbon Growth: Role of Diffusion </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Bronner%2C+C">Christopher Bronner</a>, <a href="/search/cond-mat?searchtype=author&query=Marangoni%2C+T">Tomas Marangoni</a>, <a href="/search/cond-mat?searchtype=author&query=Rizzo%2C+D+J">Daniel J. Rizzo</a>, <a href="/search/cond-mat?searchtype=author&query=Durr%2C+R">Rebecca Durr</a>, <a href="/search/cond-mat?searchtype=author&query=J%C3%B8rgensen%2C+J+H">Jakob Holm J酶rgensen</a>, <a href="/search/cond-mat?searchtype=author&query=Fischer%2C+F+R">Felix R. Fischer</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.09191v1-abstract-short" style="display: inline;"> Deterministic bottom-up approaches for synthesizing atomically well-defined graphene nanoribbons (GNRs) largely rely on the surface-catalyzed activation of selected labile bonds in a molecular precursor followed by step growth polymerization and cyclodehydrogenation. While the majority of successful GNR precursors rely on the homolytic cleavage of thermally labile C-Br bonds, the introduction of w… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.09191v1-abstract-full').style.display = 'inline'; document.getElementById('1703.09191v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.09191v1-abstract-full" style="display: none;"> Deterministic bottom-up approaches for synthesizing atomically well-defined graphene nanoribbons (GNRs) largely rely on the surface-catalyzed activation of selected labile bonds in a molecular precursor followed by step growth polymerization and cyclodehydrogenation. While the majority of successful GNR precursors rely on the homolytic cleavage of thermally labile C-Br bonds, the introduction of weaker C-I bonds provides access to monomers that can be polymerized at significantly lower temperatures, thus helping to increase the flexibility of the GNR synthesis process. Scanning tunneling microscopy (STM) imaging of molecular precursors, activated intermediates, and polymers resulting from stepwise thermal annealing of both Br and I substituted precursors for chevron GNRs reveals that the polymerization of both precursors proceeds at similar temperatures on Au(111). This observation is consistent with diffusion-limited polymerization of the surface-stabilized radical intermediates that emerge from homolytic cleavage of either the C-Br or the C-I bonds. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.09191v1-abstract-full').style.display = 'none'; document.getElementById('1703.09191v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 27 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">23 pages, 5 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.03151">arXiv:1703.03151</a> <span> [<a href="https://arxiv.org/pdf/1703.03151">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/nphys4174">10.1038/nphys4174 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+C">Chaofan Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Pedramrazi%2C+Z">Zahra Pedramrazi</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Jia%2C+C">Chunjing Jia</a>, <a href="/search/cond-mat?searchtype=author&query=Moritz%2C+B">Brian Moritz</a>, <a href="/search/cond-mat?searchtype=author&query=Claassen%2C+M">Martin Claassen</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Jiang%2C+J">Juan Jiang</a>, <a href="/search/cond-mat?searchtype=author&query=Yan%2C+H">Hao Yan</a>, <a href="/search/cond-mat?searchtype=author&query=Hashimoto%2C+M">Makoto Hashimoto</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+D">Donghui Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Moore%2C+R+G">Robert G. Moore</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Chancuk Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Hussain%2C+Z">Zahid Hussain</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yulin Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Ugeda%2C+M+M">Miguel M. Ugeda</a>, <a href="/search/cond-mat?searchtype=author&query=Liu%2C+Z">Zhi Liu</a>, <a href="/search/cond-mat?searchtype=author&query=Xie%2C+X">Xiaoming Xie</a>, <a href="/search/cond-mat?searchtype=author&query=Devereaux%2C+T+P">Thomas P. Devereaux</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a> , et al. (1 additional authors not shown) </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.03151v1-abstract-short" style="display: inline;"> A quantum spin Hall (QSH) insulator is a novel two-dimensional quantum state of matter that features quantized Hall conductance in the absence of magnetic field, resulting from topologically protected dissipationless edge states that bridge the energy gap opened by band inversion and strong spin-orbit coupling. By investigating electronic structure of epitaxially grown monolayer 1T'-WTe2 using ang… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.03151v1-abstract-full').style.display = 'inline'; document.getElementById('1703.03151v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.03151v1-abstract-full" style="display: none;"> A quantum spin Hall (QSH) insulator is a novel two-dimensional quantum state of matter that features quantized Hall conductance in the absence of magnetic field, resulting from topologically protected dissipationless edge states that bridge the energy gap opened by band inversion and strong spin-orbit coupling. By investigating electronic structure of epitaxially grown monolayer 1T'-WTe2 using angle-resolved photoemission (ARPES) and first principle calculations, we observe clear signatures of the topological band inversion and the band gap opening, which are the hallmarks of a QSH state. Scanning tunneling microscopy measurements further confirm the correct crystal structure and the existence of a bulk band gap, and provide evidence for a modified electronic structure near the edge that is consistent with the expectations for a QSH insulator. Our results establish monolayer 1T'-WTe2 as a new class of QSH insulator with large band gap in a robust two-dimensional materials family of transition metal dichalcogenides (TMDCs). <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.03151v1-abstract-full').style.display = 'none'; document.getElementById('1703.03151v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 March, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">19 pages, 4 figures; includes Supplemental Material (11 pages, 7 figures)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1703.00115">arXiv:1703.00115</a> <span> [<a href="https://arxiv.org/pdf/1703.00115">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.3938/jkps.70.586">10.3938/jkps.70.586 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging structural transitions in organometallic molecules on Ag(100) for solar thermal energy storage </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Cho%2C+J">Jongweon Cho</a>, <a href="/search/cond-mat?searchtype=author&query=Pechenezhskiy%2C+I+V">Ivan V. Pechenezhskiy</a>, <a href="/search/cond-mat?searchtype=author&query=Berbil-Bautista%2C+L">Luis Berbil-Bautista</a>, <a href="/search/cond-mat?searchtype=author&query=Meier%2C+S+K">Steven K. Meier</a>, <a href="/search/cond-mat?searchtype=author&query=Vollhardt%2C+K+P+C">K. Peter C. Vollhardt</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1703.00115v1-abstract-short" style="display: inline;"> The use of opto-thermal molecular energy storage at the nanoscale creates new opportunities for powering future microdevices with flexible synthetic tailorability. Practical application of these molecular materials, however, requires a deeper microscopic understanding of how their behavior is altered by the presence of different types of substrates. Here we present single-molecule resolved scannin… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.00115v1-abstract-full').style.display = 'inline'; document.getElementById('1703.00115v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1703.00115v1-abstract-full" style="display: none;"> The use of opto-thermal molecular energy storage at the nanoscale creates new opportunities for powering future microdevices with flexible synthetic tailorability. Practical application of these molecular materials, however, requires a deeper microscopic understanding of how their behavior is altered by the presence of different types of substrates. Here we present single-molecule resolved scanning tunneling microscopy imaging of thermally- and optically-induced structural transitions in (fulvalene)tetracarbonyldiruthenium molecules adsorbed onto a Ag(100) surface as a prototype system. Both the parent complex and the photoisomer display distinct thermally-driven phase transformations when they are in contact with a Ag(100) surface. This behavior is consistent with the loss of carbonyl ligands due to strong molecule-surface coupling. Ultraviolet radiation induces marked structural changes only in the intact parent complex, thus indicating a photoisomerization reaction. These results demonstrate how stimuli-induced structural transitions in this class of molecule depend on the nature of the underlying substrate. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1703.00115v1-abstract-full').style.display = 'none'; document.getElementById('1703.00115v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 28 February, 2017; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2017. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1612.05359">arXiv:1612.05359</a> <span> [<a href="https://arxiv.org/pdf/1612.05359">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> </div> <p class="title is-5 mathjax"> Observation of Ultralong Valley Lifetime in WSe2/MoS2 Heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Kim%2C+J">Jonghwan Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Jin%2C+C">Chenhao Jin</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+B">Bin Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Cai%2C+H">Hui Cai</a>, <a href="/search/cond-mat?searchtype=author&query=Zhao%2C+T">Tao Zhao</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+P">Puiyee Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1612.05359v1-abstract-short" style="display: inline;"> The valley degree of freedom in two-dimensional (2D) crystals recently emerged as a novel information carrier in addition to spin and charge. The intrinsic valley lifetime in 2D transition metal dichalcoginides (TMD) is expected to be remarkably long due to the unique spin-valley locking behavior, where the inter-valley scattering of electron requires simultaneously a large momentum transfer to th… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.05359v1-abstract-full').style.display = 'inline'; document.getElementById('1612.05359v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1612.05359v1-abstract-full" style="display: none;"> The valley degree of freedom in two-dimensional (2D) crystals recently emerged as a novel information carrier in addition to spin and charge. The intrinsic valley lifetime in 2D transition metal dichalcoginides (TMD) is expected to be remarkably long due to the unique spin-valley locking behavior, where the inter-valley scattering of electron requires simultaneously a large momentum transfer to the opposite valley and a flip of the electron spin. The experimentally observed valley lifetime in 2D TMDs, however, has been limited to tens of nanoseconds so far. Here we report efficient generation of microsecond-long lived valley polarization in WSe2/MoS2 heterostructures by exploiting the ultrafast charge transfer processes in the heterostructure that efficiently creates resident holes in the WSe2 layer. These valley-polarized holes exhibit near unity valley polarization and ultralong valley lifetime: we observe a valley-polarized hole population lifetime of over 1 us, and a valley depolarization lifetime (i.e. inter-valley scattering lifetime) over 40 us at 10 Kelvin. The near-perfect generation of valley-polarized holes in TMD heterostructures with ultralong valley lifetime, orders of magnitude longer than previous results, opens up new opportunities for novel valleytronics and spintronics applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1612.05359v1-abstract-full').style.display = 'none'; document.getElementById('1612.05359v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 15 December, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> December 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 6 figures, Jonghwan Kim and Chenhao Jin contributed equally to this work</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.03654">arXiv:1606.03654</a> <span> [<a href="https://arxiv.org/pdf/1606.03654">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/nphys3805">10.1038/nphys3805 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Imaging electrostatically confined Dirac fermions in graphene quantum dots </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Juwon Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Velasco%2C+J">Jairo Velasco Jr.</a>, <a href="/search/cond-mat?searchtype=author&query=Rodriguez-Nieva%2C+J+F">Joaquin F. Rodriguez-Nieva</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Levitov%2C+L+S">Leonid S. Levitov</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1606.03654v1-abstract-short" style="display: inline;"> Electrostatic confinement of charge carriers in graphene is governed by Klein tunneling, a relativistic quantum process in which particle-hole transmutation leads to unusual anisotropic transmission at pn junction boundaries. Reflection and transmission at these novel potential barriers should affect the quantum interference of electronic wavefunctions near these boundaries. Here we report the use… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.03654v1-abstract-full').style.display = 'inline'; document.getElementById('1606.03654v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.03654v1-abstract-full" style="display: none;"> Electrostatic confinement of charge carriers in graphene is governed by Klein tunneling, a relativistic quantum process in which particle-hole transmutation leads to unusual anisotropic transmission at pn junction boundaries. Reflection and transmission at these novel potential barriers should affect the quantum interference of electronic wavefunctions near these boundaries. Here we report the use of scanning tunneling microscopy (STM) to map the electronic structure of Dirac fermions confined by circular graphene pn junctions. These effective quantum dots were fabricated using a new technique involving local manipulation of defect charge within the insulating substrate beneath a graphene monolayer. Inside such graphene quantum dots we observe energy levels corresponding to quasi-bound states and we spatially visualize the quantum interference patterns of confined electrons. Dirac fermions outside these quantum dots exhibit Friedel oscillation-like behavior. Bolstered with a theoretical model describing relativistic particles in a harmonic oscillator potential, our findings yield new insight into the spatial behavior of electrostatically confined Dirac fermions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.03654v1-abstract-full').style.display = 'none'; document.getElementById('1606.03654v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 11 June, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">4 figures</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.06308">arXiv:1603.06308</a> <span> [<a href="https://arxiv.org/pdf/1603.06308">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Materials Science">cond-mat.mtrl-sci</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.6b00059">10.1021/acs.nanolett.6b00059 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Electronic Structure, Surface Doping, and Optical Response in Epitaxial WSe2 Thin Films </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Y">Yi Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Ugeda%2C+M+M">Miguel M. Ugeda</a>, <a href="/search/cond-mat?searchtype=author&query=Jin%2C+C">Chenhao Jin</a>, <a href="/search/cond-mat?searchtype=author&query=Shi%2C+S">Su-Fei Shi</a>, <a href="/search/cond-mat?searchtype=author&query=Bradley%2C+A+J">Aaron J. Bradley</a>, <a href="/search/cond-mat?searchtype=author&query=Martin-Recio%2C+A">Ana Martin-Recio</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+J">Jonghwan Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Tang%2C+S">Shujie Tang</a>, <a href="/search/cond-mat?searchtype=author&query=Kim%2C+Y">Yeongkwan Kim</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+B">Bo Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Hwang%2C+C">Choongyu Hwang</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Yulin Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Hussain%2C+Z">Zahid Hussain</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z">Zhi-Xun Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1603.06308v1-abstract-short" style="display: inline;"> High quality WSe2 films have been grown on bilayer graphene (BLG) with layer-by-layer control of thickness using molecular beam epitaxy (MBE). The combination of angle-resolved photoemission (ARPES), scanning tunneling microscopy/spectroscopy (STM/STS), and optical absorption measurements reveal the atomic and electronic structures evolution and optical response of WSe2/BLG. We observe that a bila… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.06308v1-abstract-full').style.display = 'inline'; document.getElementById('1603.06308v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.06308v1-abstract-full" style="display: none;"> High quality WSe2 films have been grown on bilayer graphene (BLG) with layer-by-layer control of thickness using molecular beam epitaxy (MBE). The combination of angle-resolved photoemission (ARPES), scanning tunneling microscopy/spectroscopy (STM/STS), and optical absorption measurements reveal the atomic and electronic structures evolution and optical response of WSe2/BLG. We observe that a bilayer of WSe2 is a direct bandgap semiconductor, when integrated in a BLG-based heterostructure, thus shifting the direct-indirect band gap crossover to trilayer WSe2. In the monolayer limit, WSe2 shows a spin-splitting of 475 meV in the valence band at the K point, the largest value observed among all the MX2 (M = Mo, W; X = S, Se) materials. The exciton binding energy of monolayer-WSe2/BLG is found to be 0.21 eV, a value that is orders of magnitude larger than that of conventional 3D semiconductors, yet small as compared to other 2D transition metal dichalcogennides (TMDCs) semiconductors. Finally, our finding regarding the overall modification of the electronic structure by an alkali metal surface electron doping opens a route to further control the electronic properties of TMDCs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.06308v1-abstract-full').style.display = 'none'; document.getElementById('1603.06308v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 20 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nano Letters 2016 </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.05558">arXiv:1603.05558</a> <span> [<a href="https://arxiv.org/pdf/1603.05558">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1038/nphys3730">10.1038/nphys3730 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Observation of charge density wave order in 1D mirror twin boundaries of single-layer MoSe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Barja%2C+S">Sara Barja</a>, <a href="/search/cond-mat?searchtype=author&query=Wickenburg%2C+S">Sebastian Wickenburg</a>, <a href="/search/cond-mat?searchtype=author&query=Liu%2C+Z">Zhen-Fei Liu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+Y">Yi Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Ryu%2C+H">Hyejin Ryu</a>, <a href="/search/cond-mat?searchtype=author&query=Ugeda%2C+M+M">Miguel M. Ugeda</a>, <a href="/search/cond-mat?searchtype=author&query=Hussain%2C+Z">Zahid Hussain</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+Z+-">Z. -X. Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Mo%2C+S">Sung-Kwan Mo</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+E">Ed Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Salmeron%2C+M+B">Miquel B. Salmeron</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a>, <a href="/search/cond-mat?searchtype=author&query=Ogletree%2C+D+F">D. Frank Ogletree</a>, <a href="/search/cond-mat?searchtype=author&query=Neaton%2C+J+B">Jeffrey B. Neaton</a>, <a href="/search/cond-mat?searchtype=author&query=Weber-Bargioni%2C+A">Alexander Weber-Bargioni</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1603.05558v1-abstract-short" style="display: inline;"> Properties of two-dimensional transition metal dichalcogenides are highly sensitive to the presence of defects in the crystal structure. A detailed understanding of defect structure may lead to control of material properties through defect engineering. Here we provide direct evidence for the existence of isolated, one-dimensional charge density waves at mirror twin boundaries in single-layer MoSe2… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.05558v1-abstract-full').style.display = 'inline'; document.getElementById('1603.05558v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.05558v1-abstract-full" style="display: none;"> Properties of two-dimensional transition metal dichalcogenides are highly sensitive to the presence of defects in the crystal structure. A detailed understanding of defect structure may lead to control of material properties through defect engineering. Here we provide direct evidence for the existence of isolated, one-dimensional charge density waves at mirror twin boundaries in single-layer MoSe2. Our low-temperature scanning tunneling microscopy/spectroscopy measurements reveal a substantial bandgap of 60 - 140 meV opening at the Fermi level in the otherwise one dimensional metallic structure. We find an energy-dependent periodic modulation in the density of states along the mirror twin boundary, with a wavelength of approximately three lattice constants. The modulations in the density of states above and below the Fermi level are spatially out of phase, consistent with charge density wave order. In addition to the electronic characterization, we determine the atomic structure and bonding configuration of the one-dimensional mirror twin boundary by means of high-resolution non-contact atomic force microscopy. Density functional theory calculations reproduce both the gap opening and the modulations of the density of states. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.05558v1-abstract-full').style.display = 'none'; document.getElementById('1603.05558v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 17 March, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Phys 12, 751-756 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1602.03245">arXiv:1602.03245</a> <span> [<a href="https://arxiv.org/pdf/1602.03245">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Mesoscale and Nanoscale Physics">cond-mat.mes-hall</span> </div> <div class="is-inline-block" style="margin-left: 0.5rem"> <div class="tags has-addons"> <span class="tag is-dark is-size-7">doi</span> <span class="tag is-light is-size-7"><a class="" href="https://doi.org/10.1021/acs.nanolett.5b04441">10.1021/acs.nanolett.5b04441 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nanoscale control of rewriteable doping patterns in pristine graphene/boron nitride heterostructures </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Velasco%2C+J">Jairo Velasco Jr.</a>, <a href="/search/cond-mat?searchtype=author&query=Ju%2C+L">Long Ju</a>, <a href="/search/cond-mat?searchtype=author&query=Wong%2C+D">Dillon Wong</a>, <a href="/search/cond-mat?searchtype=author&query=Kahn%2C+S">Salman Kahn</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+J">Juwon Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Tsai%2C+H">Hsin-Zon Tsai</a>, <a href="/search/cond-mat?searchtype=author&query=Germany%2C+C">Chad Germany</a>, <a href="/search/cond-mat?searchtype=author&query=Wickenburg%2C+S">Sebastian Wickenburg</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+J">Jiong Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Taniguchi%2C+T">Takashi Taniguchi</a>, <a href="/search/cond-mat?searchtype=author&query=Watanabe%2C+K">Kenji Watanabe</a>, <a href="/search/cond-mat?searchtype=author&query=Zettl%2C+A">Alex Zettl</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">Feng Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Crommie%2C+M+F">Michael F. Crommie</a> </p> <p class="abstract mathjax"> <span class="has-text-black-bis has-text-weight-semibold">Abstract</span>: <span class="abstract-short has-text-grey-dark mathjax" id="1602.03245v1-abstract-short" style="display: inline;"> Nanoscale control of charge doping in two-dimensional (2D) materials permits the realization of electronic analogs of optical phenomena, relativistic physics at low energies, and technologically promising nanoelectronics. Electrostatic gating and chemical doping are the two most common methods to achieve local control of such doping. However, these approaches suffer from complicated fabrication pr… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.03245v1-abstract-full').style.display = 'inline'; document.getElementById('1602.03245v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1602.03245v1-abstract-full" style="display: none;"> Nanoscale control of charge doping in two-dimensional (2D) materials permits the realization of electronic analogs of optical phenomena, relativistic physics at low energies, and technologically promising nanoelectronics. Electrostatic gating and chemical doping are the two most common methods to achieve local control of such doping. However, these approaches suffer from complicated fabrication processes that introduce contamination, change material properties irreversibly, and lack flexible pattern control. Here we demonstrate a clean, simple, and reversible technique that permits writing, reading, and erasing of doping patterns for 2D materials at the nanometer scale. We accomplish this by employing a graphene/boron nitride (BN) heterostructure that is equipped with a bottom gate electrode. By using electron transport and scanning tunneling microscopy (STM), we demonstrate that spatial control of charge doping can be realized with the application of either light or STM tip voltage excitations in conjunction with a gate electric field. Our straightforward and novel technique provides a new path towards on-demand graphene pn junctions and ultra-thin memory devices. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1602.03245v1-abstract-full').style.display = 'none'; document.getElementById('1602.03245v1-abstract-short').style.display = 'inline';">△ Less</a> </span> </p> <p class="is-size-7"><span class="has-text-black-bis has-text-weight-semibold">Submitted</span> 9 February, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2016. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Comments:</span> <span class="has-text-grey-dark mathjax">Accepted at Nano Letters</span> </p> </li> </ol> <nav class="pagination is-small is-centered breathe-horizontal" role="navigation" aria-label="pagination"> <a href="" class="pagination-previous is-invisible">Previous </a> <a 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