<?xml version="1.0" encoding="UTF-8"?> <feed xmlns="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/"> <title>DSpace Community: ETC</title> <link rel="alternate" href="https://oasis.postech.ac.kr/handle/2014.oak/9215" /> <subtitle>ETC</subtitle> <id>https://oasis.postech.ac.kr/handle/2014.oak/9215</id> <updated>2024-10-25T09:37:05Z</updated> <dc:date>2024-10-25T09:37:05Z</dc:date> <entry> <title>Effect of C additives with 0.5% in weight on structural, optical and superconducting properties of Ta–Nb–Hf–Zr–Ti high entropy alloy films</title> <link rel="alternate" href="https://oasis.postech.ac.kr/handle/2014.oak/124458" /> <author> <name>Le, Tien</name> </author> <author> <name>Lee, Yeonkyu</name> </author> <author> <name>Tran, Dzung T.</name> </author> <author> <name>Choi, Woo Seok</name> </author> <author> <name>Kang, Won Nam</name> </author> <author> <name>Yun, Jinyoung</name> </author> <author> <name>Kim, Jeehoon</name> </author> <author> <name>Song, Jaegu</name> </author> <author> <name>Han, Yoonseok</name> </author> <author> <name>Park, Tuson</name> </author> <author> <name>Tran, Duc H.</name> </author> <author> <name>Jung, Soon-Gil</name> </author> <author> <name>Hwang, Jungseek</name> </author> <id>https://oasis.postech.ac.kr/handle/2014.oak/124458</id> <updated>2024-10-21T05:20:21Z</updated> <published>2024-12-01T00:00:00Z</published> <summary type="text">Title: Effect of C additives with 0.5% in weight on structural, optical and superconducting properties of Ta–Nb–Hf–Zr–Ti high entropy alloy films Authors: Le, Tien; Lee, Yeonkyu; Tran, Dzung T.; Choi, Woo Seok; Kang, Won Nam; Yun, Jinyoung; Kim, Jeehoon; Song, Jaegu; Han, Yoonseok; Park, Tuson; Tran, Duc H.; Jung, Soon-Gil; Hwang, Jungseek Abstract: We investigated the superconducting (SC) properties of Ta-Nb-Hf-Zr-Ti high-entropy alloy (HEA) thin films with 0.5 % weight C additives. The C additives stabilize the structural properties and enhance the SC critical properties, including mu 0 H c2 (13.45 T) and T c (7.5 K). The reflectance of the C-added HEA film is enhanced in the low-energy region, resulting in a higher optical conductivity, which is consistent with the lower electrical resistivity. In addition, we observed SC vortices in the C-added HEA film using magnetic force microscopy. The magnetic penetration depths (7) 7 ) of the pure HEA and C-added HEA films were estimated from their Meissner force curves by comparing them with those of a reference Nb film. At 4.2 K, the 7 of the C-added film is 360 nm, shorter than that of the pure HEA film (560 nm), indicating stronger superconductivity against an applied magnetic field.</summary> <dc:date>2024-12-01T00:00:00Z</dc:date> </entry> <entry> <title>Influence of the reactive gas mixture on the superconducting properties of nitrogen-doped aluminum thin films</title> <link rel="alternate" href="https://oasis.postech.ac.kr/handle/2014.oak/124216" /> <author> <name>Lee, Yeonkyu</name> </author> <author> <name>Lee, Chanyoung</name> </author> <author> <name>Yun, Jinyoung</name> </author> <author> <name>Sirena, M.</name> </author> <author> <name>Kim, Jeehoon</name> </author> <author> <name>Haberkorn, N.</name> </author> <id>https://oasis.postech.ac.kr/handle/2014.oak/124216</id> <updated>2024-10-21T05:20:31Z</updated> <published>2024-12-01T00:00:00Z</published> <summary type="text">Title: Influence of the reactive gas mixture on the superconducting properties of nitrogen-doped aluminum thin films Authors: Lee, Yeonkyu; Lee, Chanyoung; Yun, Jinyoung; Sirena, M.; Kim, Jeehoon; Haberkorn, N. Abstract: We present a correlation between disorder and superconducting properties in nitrogen-doped aluminum thin films, ranging from a few nitrogen impurities to the insulating limit due to AlN formation. Samples were deposited via reactive sputtering on (100) silicon substrates with native oxide at room temperature. Our findings show that adding nitrogen increases the superconducting critical temperature (Tc) compared to pure metal films. By varying the nitrogen/argon ratio up to 6 %, we observed a dome-like Tc behavior: 2 K at low concentrations, peaking at 3.3 K at intermediate concentrations, and then dropping as the samples become insulating (≈ 4.4 %). Increasing nitrogen raises resistivity and shifts the material from metallic to semiconductor-like behavior. Disorder impacts the upper critical field, starting at 0.2 T for low nitrogen content and reaching up to 3.2 T for nitrogen-rich samples with Tc = 2.2 K. Current-voltage curves reveal typical vortex dissipation, as expected for type II superconductors. © 2024 Elsevier B.V.</summary> <dc:date>2024-12-01T00:00:00Z</dc:date> </entry> <entry> <title>Engineering of protective surfaces for retarding selenium leaching by self-growth of rGO@Ni Se on carbon nanofibers for potassium ion batteries</title> <link rel="alternate" href="https://oasis.postech.ac.kr/handle/2014.oak/123910" /> <author> <name>Lee, Yuhyeon</name> </author> <author> <name>Kim, Hongjung</name> </author> <author> <name>Son, Hyeonwook</name> </author> <author> <name>Kim, Moonsu</name> </author> <author> <name>Lee, Gibaek</name> </author> <id>https://oasis.postech.ac.kr/handle/2014.oak/123910</id> <updated>2024-08-08T01:20:17Z</updated> <published>2024-09-01T00:00:00Z</published> <summary type="text">Title: Engineering of protective surfaces for retarding selenium leaching by self-growth of rGO@Ni Se on carbon nanofibers for potassium ion batteries Authors: Lee, Yuhyeon; Kim, Hongjung; Son, Hyeonwook; Kim, Moonsu; Lee, Gibaek Abstract: K-ion batteries (PIBs) are promising alternatives to Li-ion and Na-ion batteries (LIBs/SIBs). However, the ionic radius of K+ (1.38 Å) is larger than that of Li+ (0.76 Å), consequently leading to sluggish diffusion, low capacity, and poor cycling performance in intercalation- and conversion-type K-storage technologies. To address these issues, rGO-coated nickel selenide on carbon nanofiber (rGO@NixSey-CNF) and nickel selenide on carbon nanofiber (NixSey-CNF) were developed as anode electrodes for PIBs. To improve the electrochemical properties and prevent Se leaching during the charging/discharging of nickel selenide, the surface of the NixSey particles was coated with rGO. The rGO coating not only protected Se but also improved the conductivity and cycling performance. rGO@NixSey-CNF delivered an excellent charge-specific capacity of ∼ 126 mAh g−1 at 100 mA g−1 over 200 cycles, with an initial coulombic efficiency of approximately 50 %, as well as 50 % capacity retention, attributed to the retarded leaching of Se through the rGO coating. These findings provide new insights for developing highly reversible Ni-based anode materials for advanced PIBs.</summary> <dc:date>2024-09-01T00:00:00Z</dc:date> </entry> <entry> <title>Vortex confinement through an unquantized magnetic flux</title> <link rel="alternate" href="https://oasis.postech.ac.kr/handle/2014.oak/123948" /> <author> <name>Kim, Geunyong</name> </author> <author> <name>Yun, Jinyoung</name> </author> <author> <name>Yang, Jinho</name> </author> <author> <name>Yang, Ilgyu</name> </author> <author> <name>Wulferding, Dirk</name> </author> <author> <name>KIM, JEE HOON</name> </author> <id>https://oasis.postech.ac.kr/handle/2014.oak/123948</id> <updated>2024-09-24T06:01:26Z</updated> <published>2024-09-01T00:00:00Z</published> <summary type="text">Title: Vortex confinement through an unquantized magnetic flux Authors: Kim, Geunyong; Yun, Jinyoung; Yang, Jinho; Yang, Ilgyu; Wulferding, Dirk; KIM, JEE HOON Abstract: Geometrically confined superconductors often experience a breakdown in the quantization of magnetic flux owing to the incomplete screening of the supercurrent against field penetration. In this study, we report that magnetic field confinement occurs regardless of the dimensionality of the system, even extending to 1D linear potential systems. By using a vector-field magnetic force microscope, we successfully create a vortex-antivortex pair connected by a 1D unquantized magnetic flux in ultrathin superconducting films. Through an investigation of the manipulation and thermal behavior of the vortex pair, we uncover a long-range interaction mediated by the unquantized magnetic flux. These findings suggest a universal phenomenon of unquantized magnetic flux formation, independent of the geometry of the system. Our results present an experimental route for investigating the impact of confinement on superconducting properties and order parameters in unconventional superconductors characterized by extremely low dimensionality. We demonstrate a 1D linear potential system in superconducting films by creating vortex-antivortex pairs linked by either quantized or unquantized magnetic flux. Our study of vortex pair manipulation and thermal behavior reveals a 1D force mediated by unquantized magnetic flux. This discovery suggests a universal mechanism for forming 1D force systems, offering a new paradigm in the physics of 1D forces.</summary> <dc:date>2024-09-01T00:00:00Z</dc:date> </entry> </feed>