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On the Superconducting Critical Temperature of Heavily Disordered Interfaces Hosting Multi-Gap Superconductivity. COATINGS 2021. [DOI: 10.3390/coatings12010030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
LaAlO3/SrTiO3 interfaces are a nice example of a two-dimensional electron gas, whose carrier density can be varied by top- and back-gating techniques. Due to the electron confinement near the interface, the two-dimensional band structure is split into sub-bands, and more than one sub-band can be filled when the carrier density increases. These interfaces also host superconductivity, and the interplay of two-dimensionality, multi-band character, with the possible occurrence of multi-gap superconductivity and disorder calls for a better understanding of finite-bandwidth effects on the superconducting critical temperature of heavily disordered multi-gap superconductors.
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Kim T, Kim SI, Joo S, Kim S, Jeon J, Hong J, Doh YJ, Baek SH, Koo HC. A possible superconductor-like state at elevated temperatures near metal electrodes in an LaAlO 3/SrTiO 3 interface. Sci Rep 2018; 8:11558. [PMID: 30069013 PMCID: PMC6070483 DOI: 10.1038/s41598-018-29945-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 07/20/2018] [Indexed: 11/09/2022] Open
Abstract
We experimentally investigated the transport properties near metal electrodes installed on a conducting channel in a LaAlO3/SrTiO3 interface. The local region around the Ti and Al electrodes has a higher electrical conductance than that of other regions, where the upper limits of the temperature and magnetic field can be well defined. Beyond these limits, the conductance abruptly decreases, as in the case of a superconductor. The samples with the Ti- or Al-electrode have an upper-limit temperature of approximately 4 K, which is 10 times higher than the conventional superconducting critical temperature of LaAlO3/SrTiO3 interfaces and delta-doped SrTiO3. This phenomenon is explained by the mechanism of electron transfer between the metal electrodes and electronic d-orbitals in the LaAlO3/SrTiO3 interface. The transferred electrons trigger a phase transition to a superconductor-like state. Our results contribute to the deep understanding of the superconductivity in the LaAlO3/SrTiO3 interface and will be helpful for the development of high-temperature interface superconductors.
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Affiliation(s)
- Taeyueb Kim
- Center for Electromagnetic Metrology, Korea Research Institute of Standards and Science, Daejeon, 34113, Korea
| | - Shin-Ik Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Sungjung Joo
- Center for Electromagnetic Metrology, Korea Research Institute of Standards and Science, Daejeon, 34113, Korea
| | - Sangsu Kim
- Department of Display and Semiconductor Physics, Korea University, Sejong, 30019, Korea
| | - Jeehoon Jeon
- Department of Display and Semiconductor Physics, Korea University, Sejong, 30019, Korea
- Center of Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Jinki Hong
- Department of Display and Semiconductor Physics, Korea University, Sejong, 30019, Korea.
| | - Yong-Joo Doh
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea
| | - Seung-Hyub Baek
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
- Division of Nano & Information Technology, KIST School, Korea University of Science and Technology, Seoul, 02792, Korea
| | - Hyun Cheol Koo
- Center of Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea.
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea.
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Li C, Hong Y, Xue H, Wang X, Li Y, Liu K, Jiang W, Liu M, He L, Dou R, Xiong C, Nie J. Formation of Two-dimensional Electron Gas at Amorphous/Crystalline Oxide Interfaces. Sci Rep 2018; 8:404. [PMID: 29321497 PMCID: PMC5762893 DOI: 10.1038/s41598-017-18746-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 12/17/2017] [Indexed: 11/27/2022] Open
Abstract
Experimentally, we found the percentage of low valence cations, the ionization energy of cations in film, and the band gap of substrates to be decisive for the formation of two-dimensional electron gas at the interface of amorphous/crystalline oxide (a-2DEG). Considering these findings, we inferred that the charge transfer from the film to the interface should be the main mechanism of a-2DEG formation. This charge transfer is induced by oxygen defects in film and can be eliminated by the electron-absorbing process of cations in the film. Based on this, we propose a simple dipole model that successfully explains the origin of a-2DEG, our experimental findings, and some important properties of a-2DEG.
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Affiliation(s)
- ChengJian Li
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - YanPeng Hong
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - HongXia Xue
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - XinXin Wang
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Yongchun Li
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Kejian Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Weimin Jiang
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Mingrui Liu
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Lin He
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - RuiFen Dou
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - ChangMin Xiong
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - JiaCai Nie
- Department of Physics, Beijing Normal University, Beijing, 100875, China.
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