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</div> <div class="control"> <button class="button is-small is-link">Go</button> </div> </div> </form> </div> </div> <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/2410.19999">arXiv:2410.19999</a> <span> [<a href="https://arxiv.org/pdf/2410.19999">pdf</a>, <a href="https://arxiv.org/format/2410.19999">other</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"> Ultrabroadband THz Conductivity of Gated Graphene In- and Out-of-equilibrium </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Coslovich%2C+G">G. Coslovich</a>, <a href="/search/cond-mat?searchtype=author&query=Smith%2C+R+P">R. P. Smith</a>, <a href="/search/cond-mat?searchtype=author&query=Shi%2C+S+-">S. -F. Shi</a>, <a href="/search/cond-mat?searchtype=author&query=Buss%2C+J+H">J. H. Buss</a>, <a href="/search/cond-mat?searchtype=author&query=Robinson%2C+J+T">J. T. Robinson</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+F">F. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</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="2410.19999v1-abstract-short" style="display: inline;"> We employ ultrabroadband terahertz (THz) spectroscopy to expose the high-frequency transport properties of Dirac fermions in monolayer graphene. By controlling the carrier concentration via tunable electrical gating, both equilibrium and transient optical conductivities are obtained for a range of Fermi levels. The frequency-dependent equilibrium response is determined through a combination of tim… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19999v1-abstract-full').style.display = 'inline'; document.getElementById('2410.19999v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2410.19999v1-abstract-full" style="display: none;"> We employ ultrabroadband terahertz (THz) spectroscopy to expose the high-frequency transport properties of Dirac fermions in monolayer graphene. By controlling the carrier concentration via tunable electrical gating, both equilibrium and transient optical conductivities are obtained for a range of Fermi levels. The frequency-dependent equilibrium response is determined through a combination of time-domain THz and Fourier-transform infrared spectroscopy for energies up to the near-infrared, which also provides a measure of the gate-voltage dependent Fermi level. Transient changes in the real and imaginary parts of the graphene conductivity are electro-optically resolved for frequencies up to 15 THz after near-infrared femtosecond excitation, both at the charge-neutral point and for higher electrostatic-doping levels. Modeling of the THz response provides insight into changes of the carrier spectral weights and scattering rates, and reveals an additional broad-frequency ($\approx$ 8 THz) component to the photo-induced response, which we attribute to the zero-momentum mode of quantum-critical transport observed here in large-area CVD graphene. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2410.19999v1-abstract-full').style.display = 'none'; document.getElementById('2410.19999v1-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 October, 2024; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 2024. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2306.04900">arXiv:2306.04900</a> <span> [<a href="https://arxiv.org/pdf/2306.04900">pdf</a>, <a href="https://arxiv.org/format/2306.04900">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="Materials Science">cond-mat.mtrl-sci</span> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Accelerator Physics">physics.acc-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/10.1063/4.0000203">10.1063/4.0000203 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Relativistic ultrafast electron diffraction at high repetition rates </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Siddiqui%2C+K+M">K. M. Siddiqui</a>, <a href="/search/cond-mat?searchtype=author&query=Durham%2C+D+B">D. B. Durham</a>, <a href="/search/cond-mat?searchtype=author&query=Cropp%2C+F">F. Cropp</a>, <a href="/search/cond-mat?searchtype=author&query=Ji%2C+F">F. Ji</a>, <a href="/search/cond-mat?searchtype=author&query=Paiagua%2C+S">S. Paiagua</a>, <a href="/search/cond-mat?searchtype=author&query=Ophus%2C+C">C. Ophus</a>, <a href="/search/cond-mat?searchtype=author&query=Andresen%2C+N+C">N. C. Andresen</a>, <a href="/search/cond-mat?searchtype=author&query=Jin%2C+L">L. Jin</a>, <a href="/search/cond-mat?searchtype=author&query=Wu%2C+J">J. Wu</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+S">S. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+X">X. Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=You%2C+W">W. You</a>, <a href="/search/cond-mat?searchtype=author&query=Murnane%2C+M">M. Murnane</a>, <a href="/search/cond-mat?searchtype=author&query=Centurion%2C+M">M. Centurion</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+X">X. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Slaughter%2C+D+S">D. S. Slaughter</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Musumeci%2C+P">P. Musumeci</a>, <a href="/search/cond-mat?searchtype=author&query=Minor%2C+A+M">A. M. Minor</a>, <a href="/search/cond-mat?searchtype=author&query=Filippetto%2C+D">D. Filippetto</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="2306.04900v1-abstract-short" style="display: inline;"> The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments a… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04900v1-abstract-full').style.display = 'inline'; document.getElementById('2306.04900v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2306.04900v1-abstract-full" style="display: none;"> The ability to resolve the dynamics of matter on its native temporal and spatial scales constitutes a key challenge and convergent theme across chemistry, biology, and materials science. The last couple of decades have witnessed ultrafast electron diffraction (UED) emerge as one of the forefront techniques with the sensitivity to resolve atomic motions. Increasingly sophisticated UED instruments are being developed that are aimed at increasing the beam brightness in order to observe structural signatures, but so far they have been limited to low average current beams. Here we present the technical design and capabilities of the HiRES (High Repetition Rate Electron Scattering) instrument, which blends relativistic electrons and high repetition rates to achieve orders of magnitude improvement in average beam current compared to the existing state-of-the-art UED instruments. The setup utilizes a novel electron source to deliver femtosecond duration electron pulses at up to MHz repetition rates for UED experiments. We provide example cases of diffraction measurements on solid-state and gas-phase samples, including both micro- and nanodiffraction modes, which showcase the potential of the instrument for novel UED experiments. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2306.04900v1-abstract-full').style.display = 'none'; document.getElementById('2306.04900v1-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 June, 2023; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">13 pages, 10 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/2209.05542">arXiv:2209.05542</a> <span> [<a href="https://arxiv.org/pdf/2209.05542">pdf</a>, <a href="https://arxiv.org/format/2209.05542">other</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> <p class="title is-5 mathjax"> Revealing the order parameter dynamics of 1T-TiSe$_2$ following optical excitation </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Huber%2C+M">Maximilian Huber</a>, <a href="/search/cond-mat?searchtype=author&query=Lin%2C+Y">Yi Lin</a>, <a href="/search/cond-mat?searchtype=author&query=Dale%2C+N">Nicholas Dale</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="2209.05542v1-abstract-short" style="display: inline;"> The formation of a charge density wave state is characterized by an order parameter. The way it is established provides unique information on both the role that correlation plays in driving the charge density wave formation and the mechanism behind its formation. Here we use time and angle resolved photoelectron spectroscopy to optically perturb the charge-density phase in 1T-TiSe$_2$ and follow t… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.05542v1-abstract-full').style.display = 'inline'; document.getElementById('2209.05542v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2209.05542v1-abstract-full" style="display: none;"> The formation of a charge density wave state is characterized by an order parameter. The way it is established provides unique information on both the role that correlation plays in driving the charge density wave formation and the mechanism behind its formation. Here we use time and angle resolved photoelectron spectroscopy to optically perturb the charge-density phase in 1T-TiSe$_2$ and follow the recovery of its order parameter as a function of energy, momentum and excitation density. Our results reveal that two distinct orders contribute to the gap formation, a CDW order and pseudogap-like order, manifested by an overall robustness to optical excitation. A detailed analysis of the magnitude of the the gap as a function of excitation density and delay time reveals the excitonic long-range nature of the CDW gap and the short-range Jahn-Teller character of the pseudogap order. In contrast to the gap, the intensity of the folded Se$_{4p}$* band can only give access to the excitonic order. These results provide new information into the the long standing debate on the origin of the gap in TiSe$_2$ and place it in the same context of other quantum materials where a pseudogap phase appears to be a precursor of long-range order. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2209.05542v1-abstract-full').style.display = 'none'; document.getElementById('2209.05542v1-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 September, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">6 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/2206.08951">arXiv:2206.08951</a> <span> [<a href="https://arxiv.org/pdf/2206.08951">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"> Denoising Scanning Tunneling Microscopy Images of Graphene with Supervised Machine Learning </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Joucken%2C+F">Fr茅d茅ric Joucken</a>, <a href="/search/cond-mat?searchtype=author&query=Davenport%2C+J+L">John L. Davenport</a>, <a href="/search/cond-mat?searchtype=author&query=Ge%2C+Z">Zhehao Ge</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=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=Velasco%2C+J">Jairo Velasco Jr.</a>, <a href="/search/cond-mat?searchtype=author&query=Lagoute%2C+J">J茅r么me Lagoute</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="2206.08951v2-abstract-short" style="display: inline;"> Machine learning (ML) methods are extraordinarily successful at denoising photographic images. The application of such denoising methods to scientific images is, however, often complicated by the difficulty in experimentally obtaining a suitable expected result as an input to training the ML network. Here, we propose and demonstrate a simulation-based approach to address this challenge for denoisi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08951v2-abstract-full').style.display = 'inline'; document.getElementById('2206.08951v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2206.08951v2-abstract-full" style="display: none;"> Machine learning (ML) methods are extraordinarily successful at denoising photographic images. The application of such denoising methods to scientific images is, however, often complicated by the difficulty in experimentally obtaining a suitable expected result as an input to training the ML network. Here, we propose and demonstrate a simulation-based approach to address this challenge for denoising atomic-scale scanning tunneling microscopy (STM) images, which consists of training a convolutional neural network on STM images simulated based on a tight-binding electronic structure model. As model materials, we consider graphite and its mono- and few-layer counterpart, graphene. With the goal of applying it to any experimental STM image obtained on graphitic systems, the network was trained on a set of simulated images with varying characteristics such as tip height, sample bias, atomic-scale defects, and non-linear background. Denoising of both simulated and experimental images with this approach is compared to that of commonly-used filters, revealing a superior outcome of the ML method in the removal of noise as well as scanning artifacts - including on features not simulated in the training set. An extension to larger STM images is further discussed, along with intrinsic limitations arising from training set biases that discourage application to fundamentally unknown surface features. The approach demonstrated here provides an effective way to remove noise and artifacts from typical STM images, yielding the basis for further feature discernment and automated processing. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2206.08951v2-abstract-full').style.display = 'none'; document.getElementById('2206.08951v2-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 November, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 17 June, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 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">Includes SM</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2205.05821">arXiv:2205.05821</a> <span> [<a href="https://arxiv.org/pdf/2205.05821">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="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/10.1103/PhysRevB.106.L081117">10.1103/PhysRevB.106.L081117 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Exciton-Driven Renormalization of Quasiparticle Band Structure in Monolayer MoS2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lin%2C+Y">Yi Lin</a>, <a href="/search/cond-mat?searchtype=author&query=Chan%2C+Y">Yang-hao Chan</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+W">Woojoo Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+L">Li-Syuan Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+Z">Zhenglu Li</a>, <a href="/search/cond-mat?searchtype=author&query=Chang%2C+W">Wen-Hao Chang</a>, <a href="/search/cond-mat?searchtype=author&query=Shih%2C+C">Chih-Kang Shih</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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=Lanzara%2C+A">Alessandra Lanzara</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="2205.05821v1-abstract-short" style="display: inline;"> Optical excitation serves as a powerful approach to control the electronic structure of layered Van der Waals materials via many-body screening effects, induced by photoexcited free carriers, or via light-driven coherence, such as optical Stark and Bloch-Siegert effects. Although theoretical work has also pointed to an exotic mechanism of renormalizing band structure via excitonic correlations in… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.05821v1-abstract-full').style.display = 'inline'; document.getElementById('2205.05821v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2205.05821v1-abstract-full" style="display: none;"> Optical excitation serves as a powerful approach to control the electronic structure of layered Van der Waals materials via many-body screening effects, induced by photoexcited free carriers, or via light-driven coherence, such as optical Stark and Bloch-Siegert effects. Although theoretical work has also pointed to an exotic mechanism of renormalizing band structure via excitonic correlations in bound electron-hole pairs (excitons), experimental observation of such exciton-driven band renormalization and the full extent of their implications is still lacking, largely due to the limitations of optical probes and the impact of screening effects. Here, by using extreme-ultraviolet time-resolved angle-resolved photoemission spectroscopy together with excitonic many-body theoretical calculations, we directly unmask the band renormalization effects driven by excitonic correlations in a monolayer semiconductor. We revealed a surprising bandgap opening, increased by 40 meV, and a simultaneous enhancement of band effective mass. Our findings unmask the novel exciton-driven mechanism towards the band engineering in photoexcited semiconducting materials, opening a new playground to manipulate the transient energy states in layered quantum materials via optical controls of excitonic many-body correlations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2205.05821v1-abstract-full').style.display = 'none'; document.getElementById('2205.05821v1-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 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2022. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2204.12714">arXiv:2204.12714</a> <span> [<a href="https://arxiv.org/pdf/2204.12714">pdf</a>, <a href="https://arxiv.org/format/2204.12714">other</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/10.1016/j.jpcs.2022.110740">10.1016/j.jpcs.2022.110740 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Mapping the dispersion of the occupied and unoccupied band structure in photoexcited 1T-TiSe$_2$ </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Huber%2C+M">Maximilian Huber</a>, <a href="/search/cond-mat?searchtype=author&query=Lin%2C+Y">Yi Lin</a>, <a href="/search/cond-mat?searchtype=author&query=Dale%2C+N">Nicholas Dale</a>, <a href="/search/cond-mat?searchtype=author&query=Sailus%2C+R">Renee Sailus</a>, <a href="/search/cond-mat?searchtype=author&query=Tongay%2C+S">Sefaattin Tongay</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="2204.12714v1-abstract-short" style="display: inline;"> Charge density waves (CDW) are states of broken symmetry with a periodic modulation of charge and lattice typically leading to the opening of a gap in the band structure. In the model CDW system 1T-TiSe$_2$ such a gap opens up between its Se$_{4p}$ valence and Ti$_{3d}$ conduction band, accompanied by a change of dispersion. These changes are crucial in understanding the CDW phase, as they provide… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.12714v1-abstract-full').style.display = 'inline'; document.getElementById('2204.12714v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2204.12714v1-abstract-full" style="display: none;"> Charge density waves (CDW) are states of broken symmetry with a periodic modulation of charge and lattice typically leading to the opening of a gap in the band structure. In the model CDW system 1T-TiSe$_2$ such a gap opens up between its Se$_{4p}$ valence and Ti$_{3d}$ conduction band, accompanied by a change of dispersion. These changes are crucial in understanding the CDW phase, as they provide a measure of the Se$_{4p}$-Ti$_{3d}$ hybridization strength and characteristic mechanistic features. Using time- and angle-resolved photoelectron spectroscopy (trARPES), the unoccupied band structure is populated with near-infrared (NIR) pump pulses which allows to to directly visualize the parabolically-shaped Ti$_{3d}$ conduction band. Furthermore, we observe a transient change of effective mass in the Se$_{4p}$ valence band following photoexcitation. This occurs alongside an overall reduction due to weakening of the CDW phase and is accompanied by an oscillating component with the frequency of the characteristic A$_{1g}$ phonon. These observations, enabled by trAPRES, highlight the importance of the lattice contributions in establishing the CDW order in 1T-TiSe$_2$. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2204.12714v1-abstract-full').style.display = 'none'; document.getElementById('2204.12714v1-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 April, 2022; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> April 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">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/2009.02891">arXiv:2009.02891</a> <span> [<a href="https://arxiv.org/pdf/2009.02891">pdf</a>, <a href="https://arxiv.org/format/2009.02891">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> <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="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/s42005-021-00650-z">10.1038/s42005-021-00650-z <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrafast optical melting of trimer superstructure in layered 1T'-TaTe2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Siddiqui%2C+K+M">Khalid M. Siddiqui</a>, <a href="/search/cond-mat?searchtype=author&query=Durham%2C+D+B">Daniel B. Durham</a>, <a href="/search/cond-mat?searchtype=author&query=Cropp%2C+F">Frederick Cropp</a>, <a href="/search/cond-mat?searchtype=author&query=Ophus%2C+C">Colin Ophus</a>, <a href="/search/cond-mat?searchtype=author&query=Rajpurohit%2C+S">Sangeeta Rajpurohit</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+Y">Yanglin Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Carlstr%C3%B6m%2C+J+D">Johan D. Carlstr枚m</a>, <a href="/search/cond-mat?searchtype=author&query=Stavrakas%2C+C">Camille Stavrakas</a>, <a href="/search/cond-mat?searchtype=author&query=Mao%2C+Z">Zhiqiang Mao</a>, <a href="/search/cond-mat?searchtype=author&query=Raja%2C+A">Archana Raja</a>, <a href="/search/cond-mat?searchtype=author&query=Musumeci%2C+P">Pietro Musumeci</a>, <a href="/search/cond-mat?searchtype=author&query=Tan%2C+L+Z">Liang Z. Tan</a>, <a href="/search/cond-mat?searchtype=author&query=Minor%2C+A+M">Andrew M. Minor</a>, <a href="/search/cond-mat?searchtype=author&query=Filippetto%2C+D">Daniele Filippetto</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="2009.02891v2-abstract-short" style="display: inline;"> Quasi-two-dimensional transition-metal dichalcogenides are a key platform for exploring emergent nanoscale phenomena arising from complex interactions. Access to the underlying degrees-of-freedom on their natural time scales motivates the use of advanced ultrafast probes sensitive to self-organised atomic-scale patterns. Here, we report the first ultrafast investigation of TaTe2, which exhibits un… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.02891v2-abstract-full').style.display = 'inline'; document.getElementById('2009.02891v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2009.02891v2-abstract-full" style="display: none;"> Quasi-two-dimensional transition-metal dichalcogenides are a key platform for exploring emergent nanoscale phenomena arising from complex interactions. Access to the underlying degrees-of-freedom on their natural time scales motivates the use of advanced ultrafast probes sensitive to self-organised atomic-scale patterns. Here, we report the first ultrafast investigation of TaTe2, which exhibits unique charge and lattice trimer order characterised by a transition upon cooling from stripe-like chains into a $(3 \times 3)$ superstructure of trimer clusters. Utilising MeV-scale ultrafast electron diffraction, we capture the photo-induced TaTe2 structural dynamics -- exposing a rapid $\approx\!1.4$ ps melting of its low-temperature ordered state followed by recovery via thermalisation into a hot cluster superstructure. Density-functional calculations indicate that the initial quench is triggered by intra-trimer Ta charge transfer which destabilises the clusters, unlike melting of charge density waves in other TaX2 compounds. Our work paves the way for further exploration and ultimately rapid optical and electronic manipulation of trimer superstructures. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2009.02891v2-abstract-full').style.display = 'none'; document.getElementById('2009.02891v2-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 November, 2021; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 7 September, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 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">Main text and supplementary information: 30 pages, 4 main figures, 24 supplementary figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Communications Physics, Volume 4, Article number 152 (2021) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2008.06103">arXiv:2008.06103</a> <span> [<a href="https://arxiv.org/pdf/2008.06103">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"> Momentum resolved ground/excited states and the ultra-fast excited state dynamics of monolayer MoS2 </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lee%2C+W">Woojoo Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Lin%2C+Y">Yi Lin</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+L">Li-Shuan Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Chueh%2C+W">Wei-Chen Chueh</a>, <a href="/search/cond-mat?searchtype=author&query=Liu%2C+M">Mengke Liu</a>, <a href="/search/cond-mat?searchtype=author&query=Li%2C+X">Xiaoqin Li</a>, <a href="/search/cond-mat?searchtype=author&query=Chang%2C+W">Wen-Hao Chang</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Shih%2C+C">Chih-Kang Shih</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="2008.06103v2-abstract-short" style="display: inline;"> The emergence of transition metal dichalcogenides (TMD) as crystalline atomically thin semiconductors has created a tremendous amount of scientific and technological interest. Many novel device concepts have been proposed and realized (1-3). Nonetheless, progress in k-space investigations of ground/excited state electronic structures has been slow due to the challenge to create large scale, latera… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.06103v2-abstract-full').style.display = 'inline'; document.getElementById('2008.06103v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2008.06103v2-abstract-full" style="display: none;"> The emergence of transition metal dichalcogenides (TMD) as crystalline atomically thin semiconductors has created a tremendous amount of scientific and technological interest. Many novel device concepts have been proposed and realized (1-3). Nonetheless, progress in k-space investigations of ground/excited state electronic structures has been slow due to the challenge to create large scale, laterally homogeneous samples. Taking advantage of recent advancements in chemical vapor deposition, here we create a wafer-size MoS2 monolayer with well-aligned lateral orientation for advanced electron spectroscopy studies (4-6). Low energy electron diffraction and scanning tunneling microscopy (STM) demonstrate atomically clean surfaces with in-plane crystalline orientation. The ground state and excited state electronic structures are probed using scanning tunneling spectroscopy (STS), angle-resolved photoemission (ARPES) and time-resolved (tr-)ARPES. In addition to mapping out the momentum-space quasiparticle band structure in the valence and conduction bands, we unveil ultrafast excited state dynamics, including inter- and intra-valley carrier scattering and a rapid downward energy shift by ~ 0.2eV lower than the initial free carrier state at Sigma point. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2008.06103v2-abstract-full').style.display = 'none'; document.getElementById('2008.06103v2-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 October, 2020; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 13 August, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2020. </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/2003.04224">arXiv:2003.04224</a> <span> [<a href="https://arxiv.org/pdf/2003.04224">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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="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/10.1126/science.abd7213">10.1126/science.abd7213 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Enhanced charge density wave coherence in a light-quenched, high-temperature superconductor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wandel%2C+S">S. Wandel</a>, <a href="/search/cond-mat?searchtype=author&query=Boschini%2C+F">F. Boschini</a>, <a href="/search/cond-mat?searchtype=author&query=Neto%2C+E+H+d+S">E. H. da Silva Neto</a>, <a href="/search/cond-mat?searchtype=author&query=Shen%2C+L">L. Shen</a>, <a href="/search/cond-mat?searchtype=author&query=Na%2C+M+X">M. X. Na</a>, <a href="/search/cond-mat?searchtype=author&query=Zohar%2C+S">S. Zohar</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+Y">Y. Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Welch%2C+S+B">S. B. Welch</a>, <a href="/search/cond-mat?searchtype=author&query=Seaberg%2C+M+H">M. H. Seaberg</a>, <a href="/search/cond-mat?searchtype=author&query=Koralek%2C+J+D">J. D. Koralek</a>, <a href="/search/cond-mat?searchtype=author&query=Dakovski%2C+G+L">G. L. Dakovski</a>, <a href="/search/cond-mat?searchtype=author&query=Hettel%2C+W">W. Hettel</a>, <a href="/search/cond-mat?searchtype=author&query=Lin%2C+M">M-F. Lin</a>, <a href="/search/cond-mat?searchtype=author&query=Moeller%2C+S+P">S. P. Moeller</a>, <a href="/search/cond-mat?searchtype=author&query=Schlotter%2C+W+F">W. F. Schlotter</a>, <a href="/search/cond-mat?searchtype=author&query=Reid%2C+A+H">A. H. Reid</a>, <a href="/search/cond-mat?searchtype=author&query=Minitti%2C+M+P">M. P. Minitti</a>, <a href="/search/cond-mat?searchtype=author&query=Boyle%2C+T">T. Boyle</a>, <a href="/search/cond-mat?searchtype=author&query=He%2C+F">F. He</a>, <a href="/search/cond-mat?searchtype=author&query=Sutarto%2C+R">R. Sutarto</a>, <a href="/search/cond-mat?searchtype=author&query=Liang%2C+R">R. Liang</a>, <a href="/search/cond-mat?searchtype=author&query=Bonn%2C+D">D. Bonn</a>, <a href="/search/cond-mat?searchtype=author&query=Hardy%2C+W">W. Hardy</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Hawthorn%2C+D+G">D. G. Hawthorn</a> , et al. (6 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="2003.04224v3-abstract-short" style="display: inline;"> Superconductivity and charge density waves (CDW) are competitive, yet coexisting orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning their interaction on its natural length and time scales is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution of CDW correlations in YBa$_{2}$Cu$_{3}$O$_{6+x}$ foll… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.04224v3-abstract-full').style.display = 'inline'; document.getElementById('2003.04224v3-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="2003.04224v3-abstract-full" style="display: none;"> Superconductivity and charge density waves (CDW) are competitive, yet coexisting orders in cuprate superconductors. To understand their microscopic interdependence, a probe capable of discerning their interaction on its natural length and time scales is necessary. We use ultrafast resonant soft x-ray scattering to track the transient evolution of CDW correlations in YBa$_{2}$Cu$_{3}$O$_{6+x}$ following the quench of superconductivity by an infrared laser pulse. We observe a non-thermal response of the CDW order characterized by a near doubling of the correlation length within $\approx$ 1 picosecond of the superconducting quench. Our results are consistent with a model in which the interaction between superconductivity and CDW manifests inhomogeneously through disruption of spatial coherence, with superconductivity playing the dominant role in stabilizing CDW topological defects, such as discommensurations. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('2003.04224v3-abstract-full').style.display = 'none'; document.getElementById('2003.04224v3-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> 26 May, 2022; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 9 March, 2020; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 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">Accepted version. 34 pages, 11 figures, Main text and Supplementary Materials</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science 376, 860 (2022) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1811.00715">arXiv:1811.00715</a> <span> [<a href="https://arxiv.org/pdf/1811.00715">pdf</a>, <a href="https://arxiv.org/format/1811.00715">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link 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="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/10.1063/1.5079677">10.1063/1.5079677 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> A setup for extreme-ultraviolet ultrafast angle-resolved photoelectron spectroscopy at 50-kHz repetition rate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Buss%2C+J+H">Jan Heye Buss</a>, <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">He Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Xu%2C+Y">Yiming Xu</a>, <a href="/search/cond-mat?searchtype=author&query=Maklar%2C+J">Julian Maklar</a>, <a href="/search/cond-mat?searchtype=author&query=Joucken%2C+F">Frederic Joucken</a>, <a href="/search/cond-mat?searchtype=author&query=Zeng%2C+L">Lingkun Zeng</a>, <a href="/search/cond-mat?searchtype=author&query=Stoll%2C+S">Sebastian Stoll</a>, <a href="/search/cond-mat?searchtype=author&query=Jozwiak%2C+C">Chris Jozwiak</a>, <a href="/search/cond-mat?searchtype=author&query=Pepper%2C+J">John Pepper</a>, <a href="/search/cond-mat?searchtype=author&query=Chuang%2C+Y">Yi-De Chuang</a>, <a href="/search/cond-mat?searchtype=author&query=Denlinger%2C+J+D">Jonathan D. Denlinger</a>, <a href="/search/cond-mat?searchtype=author&query=Hussain%2C+Z">Zahid Hussain</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="1811.00715v2-abstract-short" style="display: inline;"> Time- and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.00715v2-abstract-full').style.display = 'inline'; document.getElementById('1811.00715v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1811.00715v2-abstract-full" style="display: none;"> Time- and angle-resolved photoelectron spectroscopy (trARPES) is a powerful method to track the ultrafast dynamics of quasiparticles and electronic bands in energy and momentum space. We present a setup for trARPES with 22.3 eV extreme-ultraviolet (XUV) femtosecond pulses at 50-kHz repetition rate, which enables fast data acquisition and access to dynamics across momentum space with high sensitivity. The design and operation of the XUV beamline, pump-probe setup, and UHV endstation are described in detail. By characterizing the effect of space-charge broadening, we determine an ultimate source-limited energy resolution of 60 meV, with typically 80-100 meV obtained at 1-2e10 photons/s probe flux on the sample. The instrument capabilities are demonstrated via both equilibrium and time-resolved ARPES studies of transition-metal dichalcogenides. The 50-kHz repetition rate enables sensitive measurements of quasiparticles at low excitation fluences in semiconducting MoSe$_2$, with an instrumental time resolution of 65 fs. Moreover, photo-induced phase transitions can be driven with the available pump fluence, as shown by charge density wave melting in 1T-TiSe$_2$. The high repetition-rate setup thus provides a versatile platform for sensitive XUV trARPES, from quenching of electronic phases down to the perturbative limit. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1811.00715v2-abstract-full').style.display = 'none'; document.getElementById('1811.00715v2-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> 21 February, 2019; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 1 November, 2018; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 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">11 pages, 9 figures, updated accepted version with journal ref</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Rev. Sci. Instrum. 90, 023105 (2019) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1610.00202">arXiv:1610.00202</a> <span> [<a href="https://arxiv.org/pdf/1610.00202">pdf</a>, <a href="https://arxiv.org/format/1610.00202">other</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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/10.1209/0295-5075/115/27001">10.1209/0295-5075/115/27001 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrafast Angle-Resolved Photoemission Spectroscopy of Quantum Materials </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">Christopher L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="1610.00202v1-abstract-short" style="display: inline;"> Techniques in time- and angle-resolved photoemission spectroscopy have facilitated a number of recent advances in the study of quantum materials. We review developments in this field related to the study of incoherent nonequilibrium electron dynamics, the analysis of interactions between electrons and collective excitations, the exploration of dressed-state physics, and the illumination of unoccup… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00202v1-abstract-full').style.display = 'inline'; document.getElementById('1610.00202v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1610.00202v1-abstract-full" style="display: none;"> Techniques in time- and angle-resolved photoemission spectroscopy have facilitated a number of recent advances in the study of quantum materials. We review developments in this field related to the study of incoherent nonequilibrium electron dynamics, the analysis of interactions between electrons and collective excitations, the exploration of dressed-state physics, and the illumination of unoccupied band structure. Future prospects are also discussed. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1610.00202v1-abstract-full').style.display = 'none'; document.getElementById('1610.00202v1-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 October, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> October 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">7 pages, 6 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> EPL 115, 27001 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1607.07131">arXiv:1607.07131</a> <span> [<a href="https://arxiv.org/pdf/1607.07131">pdf</a>, <a href="https://arxiv.org/format/1607.07131">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/srep29100">10.1038/srep29100 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Stimulated emission of Cooper pairs in a high-temperature cuprate superconductor </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+W">Wentao Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Miller%2C+T">Tristan Miller</a>, <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">Christopher L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Yoshida%2C+Y">Yoshiyuki Yoshida</a>, <a href="/search/cond-mat?searchtype=author&query=Eisaki%2C+H">Hiroshi Eisaki</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+D">Dung-Hai Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="1607.07131v1-abstract-short" style="display: inline;"> The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown,… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.07131v1-abstract-full').style.display = 'inline'; document.getElementById('1607.07131v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1607.07131v1-abstract-full" style="display: none;"> The concept of stimulated emission of bosons has played an important role in modern science and technology, and constitutes the working principle for lasers. In a stimulated emission process, an incoming photon enhances the probability that an excited atomic state will transition to a lower energy state and generate a second photon of the same energy. It is expected, but not experimentally shown, that stimulated emission contributes significantly to the zero resistance current in a superconductor by enhancing the probability that scattered Cooper pairs will return to the macroscopically occupied condensate instead of entering any other state. Here, we use time- and angle-resolved photoemission spectroscopy to study the initial rise of the non-equilibrium quasiparticle population in a Bi$_2$Sr$_2$CaCu$_2$O$_{8+未}$ cuprate superconductor induced by an ultrashort laser pulse. Our finding reveals significantly slower buildup of quasiparticles in the superconducting state than in the normal state. The slower buildup only occurs when the pump pulse is too weak to deplete the superconducting condensate, and for cuts inside the Fermi arc region. We propose this is a manifestation of stimulated recombination of broken Cooper pairs, and signals an important momentum space dichotomy in the formation of Cooper pairs inside and outside the Fermi arc region. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1607.07131v1-abstract-full').style.display = 'none'; document.getElementById('1607.07131v1-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 July, 2016; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 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">16 pages, 4 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Scientific Reports 6, 29100 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1606.04490">arXiv:1606.04490</a> <span> [<a href="https://arxiv.org/pdf/1606.04490">pdf</a>, <a href="https://arxiv.org/format/1606.04490">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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.93.235107">10.1103/PhysRevB.93.235107 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nonequilibrium Electron Dynamics in a Solid with a Changing Nodal Excitation Gap </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">Christopher L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Miller%2C+T+L">Tristan L. Miller</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+W">Wentao Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="1606.04490v1-abstract-short" style="display: inline;"> We develop a computationally inexpensive model to examine the dynamics of boson-assisted electron relaxation in solids, studying nonequilibrium dynamics in a metal, in a nodal superconductor with a stationary density of states, and in a nodal superconductor where the gap dynamically opens. In the metallic system, the electron population resembles a thermal population at all times, but the presence… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.04490v1-abstract-full').style.display = 'inline'; document.getElementById('1606.04490v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1606.04490v1-abstract-full" style="display: none;"> We develop a computationally inexpensive model to examine the dynamics of boson-assisted electron relaxation in solids, studying nonequilibrium dynamics in a metal, in a nodal superconductor with a stationary density of states, and in a nodal superconductor where the gap dynamically opens. In the metallic system, the electron population resembles a thermal population at all times, but the presence of even a fixed nodal gap both invalidates a purely thermal treatment and sharply curtails relaxation rates. For a gap that is allowed to open as electron relaxation proceeds, effects are even more pronounced, and gap dynamics become coupled to the dynamics of the electron population. Comparisons to experiments reveal that phase-space restrictions in the presence of a gap are likely to play a significant role in the widespread observation of coexisting femtosecond and picosecond dynamics in the cuprate high-temperature superconductors. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1606.04490v1-abstract-full').style.display = 'none'; document.getElementById('1606.04490v1-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> 14 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">12 pages, 7 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 93, 235107 (2016) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1603.07819">arXiv:1603.07819</a> <span> [<a href="https://arxiv.org/pdf/1603.07819">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/sciadv.1600735">10.1126/sciadv.1600735 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrafast Dynamics of Vibrational Symmetry Breaking in a Charge-ordered Nickelate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Coslovich%2C+G">Giacomo Coslovich</a>, <a href="/search/cond-mat?searchtype=author&query=Kemper%2C+A+F">Alexander F. Kemper</a>, <a href="/search/cond-mat?searchtype=author&query=Behl%2C+S">Sascha Behl</a>, <a href="/search/cond-mat?searchtype=author&query=Huber%2C+B">Bernhard Huber</a>, <a href="/search/cond-mat?searchtype=author&query=Bechtel%2C+H+A">Hans A. Bechtel</a>, <a href="/search/cond-mat?searchtype=author&query=Sasagawa%2C+T">Takao Sasagawa</a>, <a href="/search/cond-mat?searchtype=author&query=Martin%2C+M+C">Michael C. Martin</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="1603.07819v2-abstract-short" style="display: inline;"> The ability to probe symmetry breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the format… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.07819v2-abstract-full').style.display = 'inline'; document.getElementById('1603.07819v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1603.07819v2-abstract-full" style="display: none;"> The ability to probe symmetry breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-THz response of the model stripe compound La$_{1.75}$Sr$_{0.25}$NiO$_{4}$, yielding novel insight into its electronic and structural dynamics following an ultrafast optical quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen - as witnessed by time-delayed suppression of zone-folded Ni-O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. The hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry breaking dynamics in solids. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1603.07819v2-abstract-full').style.display = 'none'; document.getElementById('1603.07819v2-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 November, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 25 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">Comments:</span> <span class="has-text-grey-dark mathjax">21 pages, 4 figures; updated version with journal ref</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Science Advances 3, e1600735 (2017) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1503.05795">arXiv:1503.05795</a> <span> [<a href="https://arxiv.org/pdf/1503.05795">pdf</a>, <a href="https://arxiv.org/format/1503.05795">other</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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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.92.161102">10.1103/PhysRevB.92.161102 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Influence of Optically Quenched Superconductivity on Quasiparticle Relaxation Rates in Bi2Sr2CaCu2O8+delta </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">Christopher L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Zhang%2C+W">Wentao Zhang</a>, <a href="/search/cond-mat?searchtype=author&query=Miller%2C+T+L">Tristan L. Miller</a>, <a href="/search/cond-mat?searchtype=author&query=Affeldt%2C+G">Gregory Affeldt</a>, <a href="/search/cond-mat?searchtype=author&query=Kurashima%2C+K">Koshi Kurashima</a>, <a href="/search/cond-mat?searchtype=author&query=Jozwiak%2C+C">Chris Jozwiak</a>, <a href="/search/cond-mat?searchtype=author&query=Noji%2C+T">Takashi Noji</a>, <a href="/search/cond-mat?searchtype=author&query=Koike%2C+Y">Yoji Koike</a>, <a href="/search/cond-mat?searchtype=author&query=Eisaki%2C+H">Hiroshi Eisaki</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+D">Dung-Hai Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">Alessandra Lanzara</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="1503.05795v2-abstract-short" style="display: inline;"> We use time- and angle-resolved photoemission to measure quasiparticle relaxation dynamics across a laser-induced superconducting phase transition in Bi2Sr2CaCu2O8+delta. Whereas low-fluence measurements reveal picosecond dynamics, sharp femtosecond dynamics emerge at higher fluence. Analyses of data as a function of energy, momentum, and doping indicate that the closure of the near-nodal gap and… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05795v2-abstract-full').style.display = 'inline'; document.getElementById('1503.05795v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1503.05795v2-abstract-full" style="display: none;"> We use time- and angle-resolved photoemission to measure quasiparticle relaxation dynamics across a laser-induced superconducting phase transition in Bi2Sr2CaCu2O8+delta. Whereas low-fluence measurements reveal picosecond dynamics, sharp femtosecond dynamics emerge at higher fluence. Analyses of data as a function of energy, momentum, and doping indicate that the closure of the near-nodal gap and disruption of macroscopic coherence are primary mechanisms driving this onset. The results demonstrate the important influence of transient electronic structure on relaxation dynamics, which is relevant for developing an understanding of nonequilibrium phase transitions. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1503.05795v2-abstract-full').style.display = 'none'; document.getElementById('1503.05795v2-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 October, 2015; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 19 March, 2015; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2015. </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">6 pages, 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 92, 161102(R) (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1408.6827">arXiv:1408.6827</a> <span> [<a href="https://arxiv.org/pdf/1408.6827">pdf</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Optics">physics.optics</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/ncomms8459">10.1038/ncomms8459 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Bright high-repetition-rate source of narrowband extreme-ultraviolet harmonics beyond 22 eV </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+H">He Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Xu%2C+Y">Yiming Xu</a>, <a href="/search/cond-mat?searchtype=author&query=Ulonska%2C+S">Stefan Ulonska</a>, <a href="/search/cond-mat?searchtype=author&query=Robinson%2C+J+S">Joseph S. Robinson</a>, <a href="/search/cond-mat?searchtype=author&query=Ranitovic%2C+P">Predrag Ranitovic</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="1408.6827v2-abstract-short" style="display: inline;"> Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials, or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of corre… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.6827v2-abstract-full').style.display = 'inline'; document.getElementById('1408.6827v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1408.6827v2-abstract-full" style="display: none;"> Novel table-top sources of extreme-ultraviolet light based on high-harmonic generation yield unique insight into the fundamental properties of molecules, nanomaterials, or correlated solids, and enable advanced applications in imaging or metrology. Extending high-harmonic generation to high repetition rates portends great experimental benefits, yet efficient extreme-ultraviolet conversion of correspondingly weak driving pulses is challenging. Here, we demonstrate a highly efficient source of femtosecond extreme-ultraviolet pulses at 50-kHz repetition rate, utilizing the ultraviolet second-harmonic focused tightly into Kr gas. In this cascaded scheme, a photon flux beyond ~3e13 per second is generated at 22.3 eV, with 5e-5 conversion efficiency that surpasses similar harmonics directly driven by the fundamental by two orders of magnitude. The enhancement arises from both wavelength scaling of the atomic dipole and improved spatio-temporal phase-matching, confirmed by simulations. Spectral isolation of a single 72-meV wide harmonic renders this bright, 50-kHz extreme-ultraviolet source a powerful tool for ultrafast photoemission, nanoscale imaging and other applications. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1408.6827v2-abstract-full').style.display = 'none'; document.getElementById('1408.6827v2-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 December, 2017; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 28 August, 2014; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2014. </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, 3 figures, 1 table; updated version with journal ref</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Commun. 6, 7459 (2015) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1302.4522">arXiv:1302.4522</a> <span> [<a href="https://arxiv.org/pdf/1302.4522">pdf</a>, <a href="https://arxiv.org/ps/1302.4522">ps</a>, <a href="https://arxiv.org/format/1302.4522">other</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/10.1103/PhysRevLett.110.127404">10.1103/PhysRevLett.110.127404 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Real-time manifestation of strongly coupled spin and charge order parameters in stripe-ordered nickelates via time-resolved resonant x-ray diffraction </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Chuang%2C+Y+D">Y. D. Chuang</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+W+S">W. S. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Kung%2C+Y+F">Y. F. Kung</a>, <a href="/search/cond-mat?searchtype=author&query=Sorini%2C+A+P">A. P. Sorini</a>, <a href="/search/cond-mat?searchtype=author&query=Moritz%2C+B">B. Moritz</a>, <a href="/search/cond-mat?searchtype=author&query=Moore%2C+R+G">R. G. Moore</a>, <a href="/search/cond-mat?searchtype=author&query=Patthey%2C+L">L. Patthey</a>, <a href="/search/cond-mat?searchtype=author&query=Trigo%2C+M">M. Trigo</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+D+H">D. H. Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Kirchmann%2C+P+S">P. S. Kirchmann</a>, <a href="/search/cond-mat?searchtype=author&query=Yi%2C+M">M. Yi</a>, <a href="/search/cond-mat?searchtype=author&query=Krupin%2C+O">O. Krupin</a>, <a href="/search/cond-mat?searchtype=author&query=Langner%2C+M">M. Langner</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+Y">Y. Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+S+Y">S. Y. Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Reis%2C+D+A">D. A. Reis</a>, <a href="/search/cond-mat?searchtype=author&query=Huse%2C+N">N. Huse</a>, <a href="/search/cond-mat?searchtype=author&query=Robinson%2C+J+S">J. S. Robinson</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Schoenlein%2C+R+W">R. W. Schoenlein</a>, <a href="/search/cond-mat?searchtype=author&query=Johnson%2C+S+L">S. L. Johnson</a>, <a href="/search/cond-mat?searchtype=author&query=Forst%2C+M">M. Forst</a>, <a href="/search/cond-mat?searchtype=author&query=Doering%2C+D">D. Doering</a>, <a href="/search/cond-mat?searchtype=author&query=Denes%2C+P">P. Denes</a>, <a href="/search/cond-mat?searchtype=author&query=Schlotter%2C+W+F">W. F. Schlotter</a> , et al. (5 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="1302.4522v1-abstract-short" style="display: inline;"> We investigate the order parameter dynamics of the stripe-ordered nickelate, La$_{1.75}$Sr$_{0.25}$NiO$_4$, using time-resolved resonant X-ray diffraction. In spite of distinct spin and charge energy scales, the two order parameters' amplitude dynamics are found to be linked together due to strong coupling. Additionally, the vector nature of the spin sector introduces a longer re-orientation time… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.4522v1-abstract-full').style.display = 'inline'; document.getElementById('1302.4522v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1302.4522v1-abstract-full" style="display: none;"> We investigate the order parameter dynamics of the stripe-ordered nickelate, La$_{1.75}$Sr$_{0.25}$NiO$_4$, using time-resolved resonant X-ray diffraction. In spite of distinct spin and charge energy scales, the two order parameters' amplitude dynamics are found to be linked together due to strong coupling. Additionally, the vector nature of the spin sector introduces a longer re-orientation time scale which is absent in the charge sector. These findings demonstrate that the correlation linking the symmetry-broken states does not unbind during the non-equilibrium process, and the time scales are not necessarily associated with the characteristic energy scales of individual degrees of freedom. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1302.4522v1-abstract-full').style.display = 'none'; document.getElementById('1302.4522v1-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 February, 2013; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> February 2013. </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. Accepted by Physical Review Letter</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 110, 127404 (2013) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1205.5609">arXiv:1205.5609</a> <span> [<a href="https://arxiv.org/pdf/1205.5609">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/ncomms1837">10.1038/ncomms1837 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Phase Fluctuations and the Absence of Topological Defects in Photo-excited Charge Ordered Nickelate </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Lee%2C+W+S">W. S. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Chuang%2C+Y+D">Y. D. Chuang</a>, <a href="/search/cond-mat?searchtype=author&query=Moore%2C+R+G">R. G. Moore</a>, <a href="/search/cond-mat?searchtype=author&query=Zhu%2C+Y">Y. Zhu</a>, <a href="/search/cond-mat?searchtype=author&query=Patthey%2C+L">L. Patthey</a>, <a href="/search/cond-mat?searchtype=author&query=Trigo%2C+M">M. Trigo</a>, <a href="/search/cond-mat?searchtype=author&query=Lu%2C+D+H">D. H. Lu</a>, <a href="/search/cond-mat?searchtype=author&query=Kirchmann%2C+P+S">P. S. Kirchmann</a>, <a href="/search/cond-mat?searchtype=author&query=Krupin%2C+O">O. Krupin</a>, <a href="/search/cond-mat?searchtype=author&query=Yi%2C+M">M. Yi</a>, <a href="/search/cond-mat?searchtype=author&query=Langner%2C+M">M. Langner</a>, <a href="/search/cond-mat?searchtype=author&query=Huse%2C+N">N. Huse</a>, <a href="/search/cond-mat?searchtype=author&query=Robinson%2C+J+S">J. S. Robinson</a>, <a href="/search/cond-mat?searchtype=author&query=Chen%2C+Y">Y. Chen</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+S+Y">S. Y. Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Coslovich%2C+G">G. Coslovich</a>, <a href="/search/cond-mat?searchtype=author&query=Huber%2C+B">B. Huber</a>, <a href="/search/cond-mat?searchtype=author&query=Reis%2C+D+A">D. A. Reis</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Schoenlein%2C+R+W">R. W. Schoenlein</a>, <a href="/search/cond-mat?searchtype=author&query=Doering%2C+D">D. Doering</a>, <a href="/search/cond-mat?searchtype=author&query=Denes%2C+P">P. Denes</a>, <a href="/search/cond-mat?searchtype=author&query=Schlotter%2C+W+F">W. F. Schlotter</a>, <a href="/search/cond-mat?searchtype=author&query=Turner%2C+J+J">J. J. Turner</a>, <a href="/search/cond-mat?searchtype=author&query=Johnson%2C+S+L">S. L. Johnson</a> , et al. (10 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="1205.5609v1-abstract-short" style="display: inline;"> The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerged in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of its ability to measure material properties at atomic and electronic time scales and create excited states not accessible by the conventional means can decouple entangled degrees of freedom by vis… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1205.5609v1-abstract-full').style.display = 'inline'; document.getElementById('1205.5609v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1205.5609v1-abstract-full" style="display: none;"> The dynamics of an order parameter's amplitude and phase determines the collective behaviour of novel states emerged in complex materials. Time- and momentum-resolved pump-probe spectroscopy, by virtue of its ability to measure material properties at atomic and electronic time scales and create excited states not accessible by the conventional means can decouple entangled degrees of freedom by visualizing their corresponding dynamics in the time domain. Here, combining time-resolved femotosecond optical and resonant x-ray diffraction measurements on striped La1.75Sr0.25NiO4, we reveal unforeseen photo-induced phase fluctuations of the charge order parameter. Such fluctuations preserve long-range order without creating topological defects, unlike thermal phase fluctuations near the critical temperature in equilibrium10. Importantly, relaxation of the phase fluctuations are found to be an order of magnitude slower than that of the order parameter's amplitude fluctuations, and thus limit charge order recovery. This discovery of new aspect to phase fluctuation provides more holistic view for the importance of phase in ordering phenomena of quantum matter. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1205.5609v1-abstract-full').style.display = 'none'; document.getElementById('1205.5609v1-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 May, 2012; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2012. </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, 6 figures. Published version can be found at Nature Communications 3, 838 (2012)</span> </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1107.5021">arXiv:1107.5021</a> <span> [<a href="https://arxiv.org/pdf/1107.5021">pdf</a>, <a href="https://arxiv.org/ps/1107.5021">ps</a>, <a href="https://arxiv.org/format/1107.5021">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/nphys2027">10.1038/nphys2027 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Nodal quasiparticle meltdown in ultra-high resolution pump-probe angle-resolved photoemission </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Graf%2C+J">J. Graf</a>, <a href="/search/cond-mat?searchtype=author&query=Jozwiak%2C+C">C. Jozwiak</a>, <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">C. L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Eisaki%2C+H">H. Eisaki</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Lee%2C+D+-">D. -H. Lee</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">A. Lanzara</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="1107.5021v1-abstract-short" style="display: inline;"> High-$T_c$ cuprate superconductors are characterized by a strong momentum-dependent anisotropy between the low energy excitations along the Brillouin zone diagonal (nodal direction) and those along the Brillouin zone face (antinodal direction). Most obvious is the d-wave superconducting gap, with the largest magnitude found in the antinodal direction and no gap in the nodal direction. Additionally… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.5021v1-abstract-full').style.display = 'inline'; document.getElementById('1107.5021v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1107.5021v1-abstract-full" style="display: none;"> High-$T_c$ cuprate superconductors are characterized by a strong momentum-dependent anisotropy between the low energy excitations along the Brillouin zone diagonal (nodal direction) and those along the Brillouin zone face (antinodal direction). Most obvious is the d-wave superconducting gap, with the largest magnitude found in the antinodal direction and no gap in the nodal direction. Additionally, while antinodal quasiparticle excitations appear only below $T_c$, superconductivity is thought to be indifferent to nodal excitations as they are regarded robust and insensitive to $T_c$. Here we reveal an unexpected tie between nodal quasiparticles and superconductivity using high resolution time- and angle-resolved photoemission on optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+未}$. We observe a suppression of the nodal quasiparticle spectral weight following pump laser excitation and measure its recovery dynamics. This suppression is dramatically enhanced in the superconducting state. These results reduce the nodal-antinodal dichotomy and challenge the conventional view of nodal excitation neutrality in superconductivity. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1107.5021v1-abstract-full').style.display = 'none'; document.getElementById('1107.5021v1-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 July, 2011; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> July 2011. </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">7 pages, 3 figure. To be published in Nature Physics</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Nature Physics 7, 805 (2011) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/1001.1989">arXiv:1001.1989</a> <span> [<a href="https://arxiv.org/pdf/1001.1989">pdf</a>, <a href="https://arxiv.org/ps/1001.1989">ps</a>, <a href="https://arxiv.org/format/1001.1989">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> <span class="tag is-small is-grey tooltip is-tooltip-top" data-tooltip="Other Condensed Matter">cond-mat.other</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/10.1063/1.3273487">10.1063/1.3273487 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Vacuum space charge effect in laser-based solid-state photoemission spectroscopy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Graf%2C+J">J. Graf</a>, <a href="/search/cond-mat?searchtype=author&query=Hellmann%2C+S">S. Hellmann</a>, <a href="/search/cond-mat?searchtype=author&query=Jozwiak%2C+C">C. Jozwiak</a>, <a href="/search/cond-mat?searchtype=author&query=Smallwood%2C+C+L">C. L. Smallwood</a>, <a href="/search/cond-mat?searchtype=author&query=Hussain%2C+Z">Z. Hussain</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Kipp%2C+L">L. Kipp</a>, <a href="/search/cond-mat?searchtype=author&query=Rossnagel%2C+K">K. Rossnagel</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">A. Lanzara</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="1001.1989v1-abstract-short" style="display: inline;"> We report a systematic measurement of the space charge effect observed in the few-ps laser pulse regime in laser-based solid-state photoemission spectroscopy experiments. The broadening and the shift of a gold Fermi edge as a function of spot size, laser power, and emission angle are characterized for pulse lengths of 6 ps and 6 eV photon energy. The results are used as a benchmark for an $N$-bo… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.1989v1-abstract-full').style.display = 'inline'; document.getElementById('1001.1989v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="1001.1989v1-abstract-full" style="display: none;"> We report a systematic measurement of the space charge effect observed in the few-ps laser pulse regime in laser-based solid-state photoemission spectroscopy experiments. The broadening and the shift of a gold Fermi edge as a function of spot size, laser power, and emission angle are characterized for pulse lengths of 6 ps and 6 eV photon energy. The results are used as a benchmark for an $N$-body numerical simulation and are compared to different regimes used in photoemission spectroscopy. These results provide an important reference for the design of time- and angle-resolved photoemission spectroscopy setups and next-generation light sources. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('1001.1989v1-abstract-full').style.display = 'none'; document.getElementById('1001.1989v1-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 January, 2010; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> January 2010. </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> J. Appl. Phys. 107, 014912 (2010) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0911.2283">arXiv:0911.2283</a> <span> [<a href="https://arxiv.org/pdf/0911.2283">pdf</a>, <a href="https://arxiv.org/ps/0911.2283">ps</a>, <a href="https://arxiv.org/format/0911.2283">other</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/10.1103/PhysRevLett.104.177401">10.1103/PhysRevLett.104.177401 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Ultrafast Spectroscopy of Mid-Infrared Internal Exciton Transitions of Separated Single-Walled Carbon Nanotubes </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Wang%2C+J">Jigang Wang</a>, <a href="/search/cond-mat?searchtype=author&query=Graham%2C+M+W">Matt W. Graham</a>, <a href="/search/cond-mat?searchtype=author&query=Ma%2C+Y">Yingzhong Ma</a>, <a href="/search/cond-mat?searchtype=author&query=Fleming%2C+G+R">Graham R. Fleming</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</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="0911.2283v2-abstract-short" style="display: inline;"> We report a femtosecond mid-infrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy, oscillator strength, resonant chirality enhancement and dynamics manifest the observation of quasi-1D intra-excitonic transitions. A model of the nanotube 1s-2p c… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0911.2283v2-abstract-full').style.display = 'inline'; document.getElementById('0911.2283v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0911.2283v2-abstract-full" style="display: none;"> We report a femtosecond mid-infrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy, oscillator strength, resonant chirality enhancement and dynamics manifest the observation of quasi-1D intra-excitonic transitions. A model of the nanotube 1s-2p cross section agrees well with the signal amplitudes. Our study further reveals saturation of the photoinduced absorption with increasing phase-space filling of the correlated e-h pairs. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0911.2283v2-abstract-full').style.display = 'none'; document.getElementById('0911.2283v2-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 July, 2010; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 November, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> November 2009. </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 pages, 4 figures, final version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 104, 177401 (2010) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0903.0577">arXiv:0903.0577</a> <span> [<a href="https://arxiv.org/pdf/0903.0577">pdf</a>, <a href="https://arxiv.org/format/0903.0577">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 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/10.1063/1.3122348">10.1063/1.3122348 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Broadband electromagnetic response and ultrafast dynamics of few-layer epitaxial graphene </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Choi%2C+H">H. Choi</a>, <a href="/search/cond-mat?searchtype=author&query=Borondics%2C+F">F. Borondics</a>, <a href="/search/cond-mat?searchtype=author&query=Siegel%2C+D+A">D. A. Siegel</a>, <a href="/search/cond-mat?searchtype=author&query=Zhou%2C+S+Y">S. Y. Zhou</a>, <a href="/search/cond-mat?searchtype=author&query=Martin%2C+M+C">M. C. Martin</a>, <a href="/search/cond-mat?searchtype=author&query=Lanzara%2C+A">A. Lanzara</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</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="0903.0577v2-abstract-short" style="display: inline;"> We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0903.0577v2-abstract-full').style.display = 'inline'; document.getElementById('0903.0577v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0903.0577v2-abstract-full" style="display: none;"> We study the broadband optical conductivity and ultrafast carrier dynamics of epitaxial graphene in the few-layer limit. Equilibrium spectra of nominally buffer, monolayer, and multilayer graphene exhibit significant terahertz and near-infrared absorption, consistent with a model of intra- and interband transitions in a dense Dirac electron plasma. Non-equilibrium terahertz transmission changes after photoexcitation are shown to be dominated by excess hole carriers, with a 1.2-ps mono-exponential decay that reflects the minority-carrier recombination time. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0903.0577v2-abstract-full').style.display = 'none'; document.getElementById('0903.0577v2-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 May, 2009; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 3 March, 2009; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> March 2009. </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 pages, 3 figures, final version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Appl. Phys. Lett. 94, 172102 (2009) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/0809.2080">arXiv:0809.2080</a> <span> [<a href="https://arxiv.org/pdf/0809.2080">pdf</a>, <a href="https://arxiv.org/ps/0809.2080">ps</a>, <a href="https://arxiv.org/format/0809.2080">other</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/10.1103/PhysRevB.79.045320">10.1103/PhysRevB.79.045320 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Transient terahertz spectroscopy of excitons and unbound carriers in quasi two-dimensional electron-hole gases </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Haegele%2C+D">D. Haegele</a>, <a href="/search/cond-mat?searchtype=author&query=Carnahan%2C+M+A">M. A. Carnahan</a>, <a href="/search/cond-mat?searchtype=author&query=Chemla%2C+D+S">D. S. Chemla</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="0809.2080v2-abstract-short" style="display: inline;"> We report a comprehensive experimental study and detailed model analysis of the terahertz dielectric response and density kinetics of excitons and unbound electron-hole pairs in GaAs quantum wells. A compact expression is given, in absolute units, for the complex-valued terahertz dielectric function of intra-excitonic transitions between the 1s and higher-energy exciton and continuum levels. It… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0809.2080v2-abstract-full').style.display = 'inline'; document.getElementById('0809.2080v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="0809.2080v2-abstract-full" style="display: none;"> We report a comprehensive experimental study and detailed model analysis of the terahertz dielectric response and density kinetics of excitons and unbound electron-hole pairs in GaAs quantum wells. A compact expression is given, in absolute units, for the complex-valued terahertz dielectric function of intra-excitonic transitions between the 1s and higher-energy exciton and continuum levels. It closely describes the terahertz spectra of resonantly generated excitons. Exciton ionization and formation are further explored, where the terahertz response exhibits both intra-excitonic and Drude features. Utilizing a two-component dielectric function, we derive the underlying exciton and unbound pair densities. In the ionized state, excellent agreement is found with the Saha thermodynamic equilibrium, which provides experimental verification of the two-component analysis and density scaling. During exciton formation, in turn, the pair kinetics is quantitatively described by a Saha equilibrium that follows the carrier cooling dynamics. The terahertz-derived kinetics is, moreover, consistent with time-resolved luminescence measured for comparison. Our study establishes a basis for tracking pair densities via transient terahertz spectroscopy of photoexcited quasi-two-dimensional electron-hole gases. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('0809.2080v2-abstract-full').style.display = 'none'; document.getElementById('0809.2080v2-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 March, 2009; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 11 September, 2008; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> September 2008. </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">14 pages, 8 figures, final version</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. B. 79, 045320 (2009) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0508082">arXiv:cond-mat/0508082</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0508082">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0508082">ps</a>, <a href="https://arxiv.org/format/cond-mat/0508082">other</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/10.1103/PhysRevB.72.161314">10.1103/PhysRevB.72.161314 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Broadband THz study of excitonic resonances in the high-density regime </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Huber%2C+R">Rupert Huber</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">Robert A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Schmid%2C+B+A">Ben A. Schmid</a>, <a href="/search/cond-mat?searchtype=author&query=Chemla%2C+D+S">Daniel S. Chemla</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="cond-mat/0508082v2-abstract-short" style="display: inline;"> We report the first terahertz study of the intra-excitonic 1s-2p transition at high excitation densities in GaAs/AlGaAs quantum wells. A strong shift, broadening, and ultimately the disappearance of this resonance occurs with increasing density, after ultrafast photoexcitation at the near-infrared exciton line. Densities of excitons and unbound electron-hole pairs are followed quantitatively usi… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0508082v2-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0508082v2-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0508082v2-abstract-full" style="display: none;"> We report the first terahertz study of the intra-excitonic 1s-2p transition at high excitation densities in GaAs/AlGaAs quantum wells. A strong shift, broadening, and ultimately the disappearance of this resonance occurs with increasing density, after ultrafast photoexcitation at the near-infrared exciton line. Densities of excitons and unbound electron-hole pairs are followed quantitatively using a model of the composite terahertz dielectric response. Comparison with near-infrared absorption changes reveals a significantly enhanced energy shift and broadening of the intra-excitonic resonance. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0508082v2-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0508082v2-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> 21 September, 2005; <span class="has-text-black-bis has-text-weight-semibold">v1</span> submitted 2 August, 2005; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> August 2005. </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 pages, 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 72, 161314(R) (2005) </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0106342">arXiv:cond-mat/0106342</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0106342">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0106342">ps</a>, <a href="https://arxiv.org/format/cond-mat/0106342">other</a>] </span> </p> <div class="tags is-inline-block"> <span class="tag is-small is-link tooltip is-tooltip-top" data-tooltip="Superconductivity">cond-mat.supr-con</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/PhysRevLett.88.027003">10.1103/PhysRevLett.88.027003 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Far-infrared optical conductivity gap in superconducting MgB2 films </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Carnahan%2C+M+A">M. A. Carnahan</a>, <a href="/search/cond-mat?searchtype=author&query=Orenstein%2C+J">J. Orenstein</a>, <a href="/search/cond-mat?searchtype=author&query=Chemla%2C+D+S">D. S. Chemla</a>, <a href="/search/cond-mat?searchtype=author&query=Christen%2C+H+M">H. M. Christen</a>, <a href="/search/cond-mat?searchtype=author&query=Zhai%2C+H">H. Zhai</a>, <a href="/search/cond-mat?searchtype=author&query=Paranthaman%2C+M">M. Paranthaman</a>, <a href="/search/cond-mat?searchtype=author&query=Lowndes%2C+D+H">D. H. Lowndes</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="cond-mat/0106342v1-abstract-short" style="display: inline;"> We report the first study of the optical conductivity of MgB2 covering the range of its superconducting energy gap. Terahertz time-domain spectroscopy is utilized to determine the complex, frequency-dependent conductivity of thin films. The imaginary part reveals an inductive reponse due to the emergence of the superconducting condensate. The real part exhibits a strong depletion of oscillator s… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0106342v1-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0106342v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0106342v1-abstract-full" style="display: none;"> We report the first study of the optical conductivity of MgB2 covering the range of its superconducting energy gap. Terahertz time-domain spectroscopy is utilized to determine the complex, frequency-dependent conductivity of thin films. The imaginary part reveals an inductive reponse due to the emergence of the superconducting condensate. The real part exhibits a strong depletion of oscillator strength near 5 meV resulting from the opening of a superconducting energy gap. The gap ratio of 2Delta/kTc = 1.9 is well below the weak-coupling value, pointing to complex behavior in this novel superconductor <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0106342v1-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0106342v1-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 June, 2001; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> June 2001. </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 pages, 3 figures</span> </p> <p class="comments is-size-7"> <span class="has-text-black-bis has-text-weight-semibold">Journal ref:</span> Phys. Rev. Lett. 88, 027003 (2002). </p> </li> <li class="arxiv-result"> <div class="is-marginless"> <p class="list-title is-inline-block"><a href="https://arxiv.org/abs/cond-mat/0105502">arXiv:cond-mat/0105502</a> <span> [<a href="https://arxiv.org/pdf/cond-mat/0105502">pdf</a>, <a href="https://arxiv.org/ps/cond-mat/0105502">ps</a>, <a href="https://arxiv.org/format/cond-mat/0105502">other</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/10.1103/PhysRevLett.87.127006">10.1103/PhysRevLett.87.127006 <i class="fa fa-external-link" aria-hidden="true"></i></a></span> </div> </div> </div> <p class="title is-5 mathjax"> Parity forbidden excitations of Sr2CuO2Cl2 revealed by optical third-harmonic spectroscopy </p> <p class="authors"> <span class="search-hit">Authors:</span> <a href="/search/cond-mat?searchtype=author&query=Schumacher%2C+A+B">A. B. Schumacher</a>, <a href="/search/cond-mat?searchtype=author&query=Dodge%2C+J+S">J. S. Dodge</a>, <a href="/search/cond-mat?searchtype=author&query=Carnahan%2C+M+A">M. A. Carnahan</a>, <a href="/search/cond-mat?searchtype=author&query=Kaindl%2C+R+A">R. A. Kaindl</a>, <a href="/search/cond-mat?searchtype=author&query=Chemla%2C+D+S">D. S. Chemla</a>, <a href="/search/cond-mat?searchtype=author&query=Miller%2C+L+L">L. L. Miller</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="cond-mat/0105502v1-abstract-short" style="display: inline;"> We present the first study of nonlinear optical third harmonic generation in the strongly correlated charge-transfer insulator Sr2CuO2Cl2. For fundamental excitation in the near-infrared, the THG spectrum reveals a strongly resonant response for photon energies near 0.7 eV. Polarization analysis reveals this novel resonance to be only partially accounted for by three-photon excitation to the opt… <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0105502v1-abstract-full').style.display = 'inline'; document.getElementById('cond-mat/0105502v1-abstract-short').style.display = 'none';">▽ More</a> </span> <span class="abstract-full has-text-grey-dark mathjax" id="cond-mat/0105502v1-abstract-full" style="display: none;"> We present the first study of nonlinear optical third harmonic generation in the strongly correlated charge-transfer insulator Sr2CuO2Cl2. For fundamental excitation in the near-infrared, the THG spectrum reveals a strongly resonant response for photon energies near 0.7 eV. Polarization analysis reveals this novel resonance to be only partially accounted for by three-photon excitation to the optical charge-transfer exciton, and indicates that an even-parity excitation at 2 eV, with a_1g symmetry, participates in the third harmonic susceptibility. <a class="is-size-7" style="white-space: nowrap;" onclick="document.getElementById('cond-mat/0105502v1-abstract-full').style.display = 'none'; document.getElementById('cond-mat/0105502v1-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 May, 2001; <span class="has-text-black-bis has-text-weight-semibold">originally announced</span> May 2001. </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">Requires RevTeX v4.0beta5</span> </p> </li> </ol> <div class="is-hidden-tablet">  <span class="help" 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