1
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Chen X, Yu T, Liu Y, Sun Y, Lei M, Guo N, Fan Y, Sun X, Zhang M, Alarab F, Strocov VN, Wang Y, Zhou T, Liu X, Lu F, Liu W, Xie Y, Peng R, Xu H, Feng D. Orientation-dependent electronic structure in interfacial superconductors LaAlO 3/KTaO 3. Nat Commun 2024; 15:7704. [PMID: 39231978 PMCID: PMC11374786 DOI: 10.1038/s41467-024-51969-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 08/21/2024] [Indexed: 09/06/2024] Open
Abstract
Emergent superconductivity at the LaAlO3/KTaO3 interfaces exhibits a mysterious dependence on the KTaO3 crystallographic orientations. Here by soft X-ray angle-resolved photoemission spectroscopy, we directly resolve the electronic structure of the LaAlO3/KTaO3 interfacial superconductors and the non-superconducting counterpart. We find that the mobile electrons that contribute to the interfacial superconductivity show strong k⊥ dispersion. Comparing the superconducting and non-superconducting interfaces, the quasi-three-dimensional electron gas with over 5.5 nm spatial distribution ubiquitously exists and shows similar orbital occupations. The signature of electron-phonon coupling is observed and intriguingly dependent on the interfacial orientations. Remarkably, the stronger electron-phonon coupling signature correlates with the higher superconducting transition temperature. Our observations help scrutinize the theories on the orientation-dependent superconductivity and offer a plausible and straightforward explanation. The interfacial orientation effect that can modify the electron-phonon coupling strength over several nanometers sheds light on the applications of oxide interfaces in general.
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Affiliation(s)
- Xiaoyang Chen
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Tianlun Yu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Yuan Liu
- School of Physics, Zhejiang University, Hangzhou, China
| | - Yanqiu Sun
- School of Physics, Zhejiang University, Hangzhou, China
| | - Minyinan Lei
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Nan Guo
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Yu Fan
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Xingtian Sun
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Meng Zhang
- School of Physics, Zhejiang University, Hangzhou, China
| | - Fatima Alarab
- Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | | | - Yilin Wang
- School of Future Technology and Department of Physics, University of Science and Technology of China, Hefei, China
| | - Tao Zhou
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Xinyi Liu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Fanjin Lu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Weitao Liu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China
| | - Yanwu Xie
- School of Physics, Zhejiang University, Hangzhou, China.
| | - Rui Peng
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, China.
| | - Haichao Xu
- Advanced Materials Laboratory, State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai, China.
- Shanghai Research Center for Quantum Sciences, Shanghai, China.
| | - Donglai Feng
- National Synchrotron Radiation Laboratory and School of Nuclear Science and Technology, New Cornerstone Science Laboratory, University of Science and Technology of China, Hefei, China.
- School of Emerging Technology and Department of Physics, University of Science and Technology of China, Hefei, China.
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2
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Liu Y, Meng Q, Mahmoudi P, Wang Z, Zhang J, Yang J, Li W, Wang D, Li Z, Sorrell C, Li S. Advancing Superconductivity with Interface Engineering. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2405009. [PMID: 39104281 DOI: 10.1002/adma.202405009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 07/01/2024] [Indexed: 08/07/2024]
Abstract
The development of superconducting materials has attracted significant attention not only for their improved performance, such as high transition temperature (TC), but also for the exploration of their underlying physical mechanisms. Recently, considerable efforts have been focused on interfaces of materials, a distinct category capable of inducing superconductivity at non-superconducting material interfaces or augmenting the TC at the interface between a superconducting material and a non-superconducting material. Here, two distinct types of interfaces along with their unique characteristics are reviewed: interfacial superconductivity and interface-enhanced superconductivity, with a focus on the crucial factors and potential mechanisms responsible for enhancing superconducting performance. A series of materials systems is discussed, encompassing both historical developments and recent progress from the perspectives of technical innovations and the exploration of new material classes. The overarching goal is to illuminate pathways toward achieving high TC, expanding the potential of superconducting parameters across interfaces, and propelling superconductivity research toward practical, high-temperature applications.
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Affiliation(s)
- Yichen Liu
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Qingxiao Meng
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Pezhman Mahmoudi
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Ziyi Wang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Ji Zhang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Jack Yang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Wenxian Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Danyang Wang
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Zhi Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Chris Sorrell
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
| | - Sean Li
- UNSW Materials and Manufacturing Futures Institute, School of Materials Science and Engineering, The University of New South Wales, Kensington, NSW, 2052, Australia
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Ning Z, Qian J, Liu Y, Chen F, Zhang M, Deng L, Yuan X, Ge Q, Jin H, Zhang G, Peng W, Qiao S, Mu G, Chen Y, Li W. Coexistence of Ferromagnetism and Superconductivity at KTaO 3 Heterointerfaces. NANO LETTERS 2024; 24:7134-7141. [PMID: 38828962 DOI: 10.1021/acs.nanolett.4c02500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
The coexistence of superconductivity and ferromagnetism is a long-standing issue in superconductivity due to the antagonistic nature of these two ordered states. Experimentally identifying and characterizing novel heterointerface superconductors that coexist with magnetism presents significant challenges. Here, we report the observation of two-dimensional long-range ferromagnetic order in a KTaO3 heterointerface superconductor, showing the coexistence of superconductivity and ferromagnetism. Remarkably, our direct current superconducting quantum interference device measurements reveal an in-plane magnetization hysteresis loop persisting above room temperature. Moreover, first-principles calculations and X-ray magnetic circular dichroism measurements provide decisive insights into the origin of the observed robust ferromagnetism, attributing it to oxygen vacancies that localize electrons in nearby Ta 5d states. Our findings suggest KTaO3 heterointerfaces as time-reversal symmetry breaking superconductors, injecting fresh momentum into the exploration of the intricate interplay between superconductivity and magnetism enhanced by the strong spin-orbit coupling inherent to the heavy Ta in 5d orbitals.
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Affiliation(s)
- Zhongfeng Ning
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Jiahui Qian
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Yixin Liu
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fan Chen
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingzhu Zhang
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Liwei Deng
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinli Yuan
- Thermo Fisher Scientific China, Shanghai 201203, China
| | - Qingqin Ge
- Thermo Fisher Scientific China, Shanghai 201203, China
| | - Hua Jin
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
| | - Guanqun Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wei Peng
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shan Qiao
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Gang Mu
- National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - Wei Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
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4
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Kim J, Yu M, Lee JW, Shang SL, Kim GY, Pal P, Seo J, Campbell N, Eom K, Ramachandran R, Rzchowski MS, Oh SH, Choi SY, Liu ZK, Levy J, Eom CB. Electronic-grade epitaxial (111) KTaO 3 heterostructures. SCIENCE ADVANCES 2024; 10:eadk4288. [PMID: 38787951 PMCID: PMC11122674 DOI: 10.1126/sciadv.adk4288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 04/22/2024] [Indexed: 05/26/2024]
Abstract
KTaO3 heterostructures have recently attracted attention as model systems to study the interplay of quantum paraelectricity, spin-orbit coupling, and superconductivity. However, the high and low vapor pressures of potassium and tantalum present processing challenges to creating heterostructure interfaces clean enough to reveal the intrinsic quantum properties. Here, we report superconducting heterostructures based on high-quality epitaxial (111) KTaO3 thin films using an adsorption-controlled hybrid PLD to overcome the vapor pressure mismatch. Electrical and structural characterizations reveal that the higher-quality heterostructure interface between amorphous LaAlO3 and KTaO3 thin films supports a two-dimensional electron gas with substantially higher electron mobility, superconducting transition temperature, and critical current density than that in bulk single-crystal KTaO3-based heterostructures. Our hybrid approach may enable epitaxial growth of other alkali metal-based oxides that lie beyond the capabilities of conventional methods.
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Affiliation(s)
- Jieun Kim
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Muqing Yu
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Jung-Woo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Shun-Li Shang
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Gi-Yeop Kim
- Department of Materials Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang 37673, Republic of Korea
| | - Pratap Pal
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jinsol Seo
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea
- Department of Energy Engineering, KENTECH Institute for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH), Naju 58330, Republic of Korea
| | - Neil Campbell
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Ranjani Ramachandran
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Mark S. Rzchowski
- Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Sang Ho Oh
- Department of Energy Science, Sungkyunkwan University, Suwon 16419, Korea
- Department of Energy Engineering, KENTECH Institute for Energy Materials and Devices, Korea Institute of Energy Technology (KENTECH), Naju 58330, Republic of Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Pohang 37673, Republic of Korea
| | - Zi-Kui Liu
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
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5
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Weitzel A, Pfaffinger L, Maccari I, Kronfeldner K, Huber T, Fuchs L, Mallord J, Linzen S, Il'ichev E, Paradiso N, Strunk C. Sharpness of the Berezinskii-Kosterlitz-Thouless Transition in Disordered NbN Films. PHYSICAL REVIEW LETTERS 2023; 131:186002. [PMID: 37977616 DOI: 10.1103/physrevlett.131.186002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Accepted: 09/21/2023] [Indexed: 11/19/2023]
Abstract
We present a comprehensive investigation of the Berezinskii-Kosterlitz-Thouless transition in ultrathin strongly disordered NbN films. Measurements of resistance, current-voltage characteristics, and kinetic inductance on the very same device reveal a consistent picture of a sharp unbinding transition of vortex-antivortex pairs that fit standard renormalization group theory without extra assumptions in terms of inhomogeneity. Our experiments demonstrate that the previously observed broadening of the transition is not an intrinsic feature of strongly disordered superconductors and provide a clean starting point for the study of dynamical effects at the Berezinskii-Kosterlitz-Thouless transition.
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Affiliation(s)
- Alexander Weitzel
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Lea Pfaffinger
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Ilaria Maccari
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Klaus Kronfeldner
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Thomas Huber
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Lorenz Fuchs
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - James Mallord
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Sven Linzen
- Leibniz Institute of Photonic Technology, D-07745 Jena, Germany
| | - Evgeni Il'ichev
- Leibniz Institute of Photonic Technology, D-07745 Jena, Germany
| | - Nicola Paradiso
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
| | - Christoph Strunk
- Institute for Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany
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6
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Esswein T, Spaldin NA. First-principles calculation of electron-phonon coupling in doped KTaO3. OPEN RESEARCH EUROPE 2023; 3:177. [PMID: 38115952 PMCID: PMC10728587 DOI: 10.12688/openreseurope.16312.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 09/04/2023] [Indexed: 12/21/2023]
Abstract
Background: Motivated by the recent experimental discovery of strongly surface-plane-dependent superconductivity at surfaces of KTaO 3 single crystals, we calculate the electron-phonon coupling strength, λ, of doped KTaO 3 along the reciprocal-space high-symmetry directions. Methods:Using the Wannier-function approach implemented in the EPW package, we calculate λ across the experimentally covered doping range and compare its mode-resolved distribution along the [001], [110] and [111] reciprocal-space directions. Results: We find that the electron-phonon coupling is strongest in the optical modes around the Γ point, with some distribution to higher k values in the [001] direction. The electron-phonon coupling strength as a function of doping has a dome-like shape in all three directions and its integrated total is largest in the [001] direction and smallest in the [111] direction, in contrast to the experimentally measured trends in critical temperatures. Conclusions: This disagreement points to a non-BCS character of the superconductivity. Instead, the strong localization of λ in the soft optical modes around Γ suggests an importance of ferroelectric soft-mode fluctuations, which is supported by our findings that the mode-resolved λ values are strongly enhanced in polar structures. The inclusion of spin-orbit coupling has negligible influence on our calculated mode-resolved λ values.
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Affiliation(s)
- Tobias Esswein
- Department of Materials, ETH Zurich, Zürich, Zurich, 8093, Switzerland
| | - Nicola A. Spaldin
- Department of Materials, ETH Zurich, Zürich, Zurich, 8093, Switzerland
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7
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Zhang G, Wang L, Wang J, Li G, Huang G, Yang G, Xue H, Ning Z, Wu Y, Xu JP, Song Y, An Z, Zheng C, Shen J, Li J, Chen Y, Li W. Spontaneous rotational symmetry breaking in KTaO 3 heterointerface superconductors. Nat Commun 2023; 14:3046. [PMID: 37236987 DOI: 10.1038/s41467-023-38759-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Broken symmetries play a fundamental role in superconductivity and influence many of its properties in a profound way. Understanding these symmetry breaking states is essential to elucidate the various exotic quantum behaviors in non-trivial superconductors. Here, we report an experimental observation of spontaneous rotational symmetry breaking of superconductivity at the heterointerface of amorphous (a)-YAlO3/KTaO3(111) with a superconducting transition temperature of 1.86 K. Both the magnetoresistance and superconducting critical field in an in-plane field manifest striking twofold symmetric oscillations deep inside the superconducting state, whereas the anisotropy vanishes in the normal state, demonstrating that it is an intrinsic property of the superconducting phase. We attribute this behavior to the mixed-parity superconducting state, which is an admixture of s-wave and p-wave pairing components induced by strong spin-orbit coupling inherent to inversion symmetry breaking at the heterointerface of a-YAlO3/KTaO3. Our work suggests an unconventional nature of the underlying pairing interaction in the KTaO3 heterointerface superconductors, and brings a new broad of perspective on understanding non-trivial superconducting properties at the artificial heterointerfaces.
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Affiliation(s)
- Guanqun Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Lijie Wang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jinghui Wang
- ShanghaiTech Laboratory for Topological Physics & School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Guoan Li
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Guangyi Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Guang Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Huanyi Xue
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Zhongfeng Ning
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yueshen Wu
- ShanghaiTech Laboratory for Topological Physics & School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Jin-Peng Xu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yanru Song
- ShanghaiTech Quantum Device Lab, ShanghaiTech University, Shanghai, 201210, China.
| | - Zhenghua An
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai, 200433, China
| | - Changlin Zheng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jie Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, China.
| | - Jun Li
- ShanghaiTech Laboratory for Topological Physics & School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Yan Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Wei Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, 200433, China.
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8
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Tunable superconductivity and its origin at KTaO 3 interfaces. Nat Commun 2023; 14:951. [PMID: 36806127 PMCID: PMC9941122 DOI: 10.1038/s41467-023-36309-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 01/23/2023] [Indexed: 02/22/2023] Open
Abstract
What causes Cooper pairs to form in unconventional superconductors is often elusive because experimental signatures that connect to a specific pairing mechanism are rare. Here, we observe distinct dependences of the superconducting transition temperature Tc on carrier density n2D for electron gases formed at KTaO3 (111), (001) and (110) interfaces. For the (111) interface, a remarkable linear dependence of Tc on n2D is observed over a range of nearly one order of magnitude. Further, our study of the dependence of superconductivity on gate electric fields reveals the role of the interface in mediating superconductivity. We find that the extreme sensitivity of superconductivity to crystallographic orientation can be explained by pairing via inter-orbital interactions induced by an inversion-breaking transverse optical phonon and quantum confinement. This mechanism is also consistent with the dependence of Tc on n2D. Our study may shed light on the pairing mechanism in other superconducting quantum paraelectrics.
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9
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Sun Y, Liu Y, Pan W, Xie Y. Effects of growth temperature, oxygen pressure, laser fluence and postannealing on transport properties of superconducting LaAlO 3/KTaO 3(111) interfaces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:444004. [PMID: 36007513 DOI: 10.1088/1361-648x/ac8cc8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 08/25/2022] [Indexed: 06/15/2023]
Abstract
The recent discovery of superconductivity at EuO (or LaAlO3)/KTaO3interfaces has attracted considerable research interest. However, an extensive study on growth of these interfaces is still lacking. In this work, we have fabricated LaAlO3/KTaO3(111) interfaces by growing LaAlO3thin films on KTaO3(111) single-crystalline substrates by pulsed laser deposition. We investigated the effects of growth temperature, oxygen pressure, laser fluence, and postannealing on transport properties. We found that all these key growth parameters show important effects on transport properties, and discussed their possible mechanisms. Our present study provides useful knowledge to further optimize these interfaces.
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Affiliation(s)
- Yanqiu Sun
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yuan Liu
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Wenze Pan
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
| | - Yanwu Xie
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
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