1
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Jiao X, Dong W, Shi M, Wang H, Ding C, Wei Z, Gong G, Li Y, Li Y, Zuo B, Wang J, Zhang D, Pan M, Wang L, Xue QK. Significantly enhanced superconductivity in monolayer FeSe films on SrTiO 3(001) via metallic δ-doping. Natl Sci Rev 2024; 11:nwad213. [PMID: 38312379 PMCID: PMC10833465 DOI: 10.1093/nsr/nwad213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/19/2023] [Accepted: 07/25/2023] [Indexed: 02/06/2024] Open
Abstract
Superconductivity transition temperature (Tc) marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii-Kosterlitz-Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3(001), although the pairing temperature (Tp) is revealed to be 65-83 K by using spectroscopy characterization, the measured zero-resistance temperature ([Formula: see text]) is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3(001) surface, in which [Formula: see text] is enhanced by 12 K with a narrowed transition width ΔTc ∼ 8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3(001) surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.
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Affiliation(s)
- Xiaotong Jiao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Wenfeng Dong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Mingxia Shi
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Heng Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
| | - Zhongxu Wei
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Guanming Gong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yanan Li
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Yuanzhao Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Binjie Zuo
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Jian Wang
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Hefei National Laboratory, Hefei 230088, China
| | - Ding Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Minghu Pan
- School of Physics & Information Technology, Shaanxi Normal University, Xi'an 710119, China
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, China
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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2
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Zhao J, Zhang Q, Sui L, Niu G, Zhang Y, Wu G, Yu S, Yuan K, Yang X. Evidence of Surface-Mediated Carrier-Phonon Scattering in MXene. ACS NANO 2023. [PMID: 38009540 DOI: 10.1021/acsnano.3c07431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
In a two-dimensional (2D) metallic nanostructure, when a sample's thickness is shorter than a carrier mean free path, the ultrathin thickness may influence carrier and energy transport, owing to surface scattering. However, to date, for metallic 2D transition-metal carbides (MXenes), experiments and calculations related to surface scattering have not been performed. The contribution of ultrathin structures to carrier surface scattering in MXene is yet to be explored. Herein, to reveal this effect, we design various models, including metal/MXene, dielectric/MXene, and bulk structure, and analyze their carrier dynamics via ultrafast spectroscopy. The results related to carrier dynamics indicate that the influence of the dielectric/MXene interface and the temperature is negligible. In contrast, the carrier dynamic lifetimes are prolonged owing to weakened surface scattering in metal/MXene, which is supported by ab initio calculations. These results suggest that the carrier-phonon scattering is dominated by surface scattering. These findings can help guide effective energy transport and enhance energy conversion and catalysis.
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Affiliation(s)
- Jie Zhao
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, China
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Qi Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Laizhi Sui
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Guangming Niu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Yutong Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Guorong Wu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Shengrui Yu
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, China
| | - Kaijun Yuan
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Hefei National Laboratory, Hefei 230088, China
| | - Xueming Yang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- Hefei National Laboratory, Hefei 230088, China
- Department of Chemistry and Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
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3
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Zou X, Xie M, Wang R, Liang H, Li Y, Tian F, Sun Y, Wang C. Two-Dimensional Superconductivity in Air-Stable Single-Crystal Few-Layer Bi 3O 2S 3. J Am Chem Soc 2023; 145:20975-20984. [PMID: 37703097 DOI: 10.1021/jacs.3c06854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023]
Abstract
The progress of unconventional superconductors at the two-dimensional (2D) limit has inspired much interest. Recently, a new superconducting system was discovered in the semimetallic ternary Bi-O-S family. However, pure-phase crystals are difficult to synthesize because of the complicated stacking sequence of multiple charged layers and similar formation kinetics among ternary polytypes, leaving several fundamental issues regarding the structure-superconductivity correlation unresolved. Herein, 2D single-crystal ultrathin Bi3O2S3 nanosheets are prepared by using low-pressure chemical vapor deposition, and their atomic arrangement is clarified. Magnetotransport measurements indicate a superconducting transition at ∼6.1 K that is thickness-independent. The transport results demonstrate 2D superconducting characteristics, such as the Berezinskii-Kosterlitz-Thouless transition, and strong anisotropy with magnetic field orientations following the 2D Tinkham formula. The difference from superconductivity of powder is demonstrated from the perspective of their corresponding microstructures. These results corroborate the superconducting behavior of Bi3O2S3, providing fresh insights into the search for other bismuth oxychalcogenides and derivative BiS2-based analogues at the 2D limit.
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Affiliation(s)
- Xiaobin Zou
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Mingyuan Xie
- School of Physics, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Ruize Wang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Haikuan Liang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Yan Li
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Fei Tian
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Yong Sun
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Chengxin Wang
- School of Materials Science and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
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4
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Wan P, Zheliuk O, Yuan NFQ, Peng X, Zhang L, Liang M, Zeitler U, Wiedmann S, Hussey NE, Palstra TTM, Ye J. Orbital Fulde-Ferrell-Larkin-Ovchinnikov state in an Ising superconductor. Nature 2023:10.1038/s41586-023-05967-z. [PMID: 37225992 DOI: 10.1038/s41586-023-05967-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 03/17/2023] [Indexed: 05/26/2023]
Abstract
In superconductors possessing both time and inversion symmetries, the Zeeman effect of an external magnetic field can break the time-reversal symmetry, forming a conventional Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state characterized by Cooper pairings with finite momentum1,2. In superconductors lacking (local) inversion symmetry, the Zeeman effect may still act as the underlying mechanism of FFLO states by interacting with spin-orbit coupling (SOC). Specifically, the interplay between the Zeeman effect and Rashba SOC can lead to the formation of more accessible Rashba FFLO states that cover broader regions in the phase diagram3-5. However, when the Zeeman effect is suppressed because of spin locking in the presence of Ising-type SOC, the conventional FFLO scenarios are no longer effective. Instead, an unconventional FFLO state is formed by coupling the orbital effect of magnetic fields with SOC, providing an alternative mechanism in superconductors with broken inversion symmetries6-8. Here we report the discovery of such an orbital FFLO state in the multilayer Ising superconductor 2H-NbSe2. Transport measurements show that the translational and rotational symmetries are broken in the orbital FFLO state, providing the hallmark signatures of finite-momentum Cooper pairings. We establish the entire orbital FFLO phase diagram, consisting of a normal metal, a uniform Ising superconducting phase and a six-fold orbital FFLO state. This study highlights an alternative route to achieving finite-momentum superconductivity and provides a universal mechanism to preparing orbital FFLO states in similar materials with broken inversion symmetries.
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Affiliation(s)
- Puhua Wan
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Oleksandr Zheliuk
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Noah F Q Yuan
- School of Science, Harbin Institute of Technology, Shenzhen, China
| | - Xiaoli Peng
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Le Zhang
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Minpeng Liang
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands
| | - Uli Zeitler
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Steffen Wiedmann
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
| | - Nigel E Hussey
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Nijmegen, The Netherlands
- H. H. Wills Physics Laboratory, University of Bristol, Bristol, UK
| | - Thomas T M Palstra
- Nano Electronic Materials, University of Twente, Enschede, The Netherlands
| | - Jianting Ye
- Device Physics of Complex Materials, Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
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5
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Kim JR, Sohn B, Lee HJ, Lee S, Ko EK, Hahn S, Lee S, Kim Y, Kim D, Kim HJ, Kim Y, Son J, Ahn CH, Walker FJ, Go A, Kim M, Kim CH, Kim C, Noh TW. Heteroepitaxial Control of Fermi Liquid, Hund Metal, and Mott Insulator Phases in Single-Atomic-Layer Ruthenates. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2208833. [PMID: 36739615 DOI: 10.1002/adma.202208833] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2022] [Revised: 01/08/2023] [Indexed: 06/18/2023]
Abstract
Interfaces between dissimilar correlated oxides can offer devices with versatile functionalities, and great efforts have been made to manipulate interfacial electronic phases. However, realizing such phases is often hampered by the inability to directly access the electronic structure information; most correlated interfacial phenomena appear within a few atomic layers from the interface. Here, atomic-scale epitaxy and photoemission spectroscopy are utilized to realize the interface control of correlated electronic phases in atomic-scale ruthenate-titanate heterostructures. While bulk SrRuO3 is a ferromagnetic metal, the heterointerfaces exclusively generate three distinct correlated phases in the single-atomic-layer limit. The theoretical analysis reveals that atomic-scale structural proximity effects yield Fermi liquid, Hund metal, and Mott insulator phases in the quantum-confined SrRuO3 . These results highlight the extensive interfacial tunability of electronic phases, hitherto hidden in the atomically thin correlated heterostructure. Moreover, this experimental platform suggests a way to control interfacial electronic phases of various correlated materials.
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Affiliation(s)
- Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Byungmin Sohn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
- Department of Applied Physics, Yale University, New Haven, CT, 06520, USA
| | - Hyeong Jun Lee
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon, 34126, South Korea
| | - Sangmin Lee
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, South Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Sungsoo Hahn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Sangjae Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
| | - Younsik Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Hong Joon Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Youngdo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Jaeseok Son
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Charles H Ahn
- Department of Applied Physics, Yale University, New Haven, CT, 06520, USA
- Department of Physics, Yale University, New Haven, CT, 06520, USA
| | - Frederick J Walker
- Department of Applied Physics, Yale University, New Haven, CT, 06520, USA
| | - Ara Go
- Department of Physics, Chonnam National University, Gwangju, 61186, South Korea
| | - Miyoung Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, South Korea
| | - Choong H Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea
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6
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Mun J, Ko EK, Kang B, Gil B, Kim CH, Hahn S, Song J, Zhu Y, Sohn C, Noh TW, Kim M. Extended Oxygen Octahedral Tilt Proximity near Oxide Heterostructures. NANO LETTERS 2023; 23:1036-1043. [PMID: 36716295 DOI: 10.1021/acs.nanolett.2c04633] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The oxide interfaces between materials with different structural symmetries have been actively studied due to their novel physical properties. However, the investigation of intriguing interfacial phenomena caused by the oxygen octahedral tilt (OOT) proximity effect has not been fully exploited, as there is still no clear understanding of what determines the proximity length and what the underlying control mechanism is. Here, we achieved scalability of the OOT proximity effect in SrRuO3 (SRO) by epitaxial strain near the SRO/SrTiO3 heterointerface. We demonstrated that the OOT proximity length scale of SRO is extended from 4 unit cells to 14 unit cells by employing advanced scanning transmission electron microscopy. We also suggest that this variation may originate from changes in phonon dispersions due to electron-phonon coupling in SRO. This study will provide in-depth insights into the structural gradients of correlated systems and facilitate potential device applications.
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Affiliation(s)
- Junsik Mun
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul08826, Republic of Korea
| | - Eun Kyo Ko
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul08826, Republic of Korea
| | - Baekjune Kang
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Byeongjun Gil
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul08826, Republic of Korea
| | - Choong H Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul08826, Republic of Korea
| | - Sungsoo Hahn
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul08826, Republic of Korea
| | - Jeongkeun Song
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul08826, Republic of Korea
| | - Yimei Zhu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York11973, United States
| | - Changhee Sohn
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan44919, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul08826, Republic of Korea
| | - Miyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul08826, Republic of Korea
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul08826, Republic of Korea
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7
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Ren T, Li M, Sun X, Ju L, Liu Y, Hong S, Sun Y, Tao Q, Zhou Y, Xu ZA, Xie Y. Two-dimensional superconductivity at the surfaces of KTaO 3 gated with ionic liquid. SCIENCE ADVANCES 2022; 8:eabn4273. [PMID: 35658041 PMCID: PMC9166623 DOI: 10.1126/sciadv.abn4273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 04/19/2022] [Indexed: 05/28/2023]
Abstract
The recent discovery of superconductivity at the interfaces between KTaO3 and EuO (or LaAlO3) gives birth to the second generation of oxide interface superconductors. This superconductivity exhibits a strong dependence on the surface plane of KTaO3, in contrast to the seminal LaAlO3/SrTiO3 interface, and the superconducting transition temperature Tc is enhanced by one order of magnitude. For understanding its nature, a crucial issue arises: Is the formation of oxide interfaces indispensable for the occurrence of superconductivity? Exploiting ionic liquid (IL) gating, we are successful in achieving superconductivity at KTaO3(111) and KTaO3(110) surfaces with Tc up to 2.0 and 1.0 K, respectively. This oxide-IL interface superconductivity provides a clear evidence that the essential physics of KTaO3 interface superconductivity lies in the KTaO3 surfaces doped with electrons. Moreover, the controllability with IL technique paves the way for studying the intrinsic superconductivity in KTaO3.
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Affiliation(s)
- Tianshuang Ren
- 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, China
| | - Miaocong Li
- 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, China
| | - Xikang 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, China
| | - Lele Ju
- 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, 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, China
| | - Siyuan Hong
- 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, China
| | - 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, China
| | - Qian Tao
- 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, China
| | - Yi Zhou
- Beijing National Laboratory for Condensed Matter
Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190,
China
- Songshan Lake Materials Laboratory, Dongguan,
Guangdong 523808, China
- Kavli Institute for Theoretical Sciences, CAS Center
for Excellence in Topological Quantum Computation, University of Chinese Academy
of Sciences, Beijing 100190, China
| | - Zhu-An Xu
- 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, China
- Collaborative Innovation Center of Advanced
Microstructures, Nanjing University, Nanjing 210093, 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, China
- Collaborative Innovation Center of Advanced
Microstructures, Nanjing University, Nanjing 210093, China
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8
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Ok JM, Mohanta N, Zhang J, Yoon S, Okamoto S, Choi ES, Zhou H, Briggeman M, Irvin P, Lupini AR, Pai YY, Skoropata E, Sohn C, Li H, Miao H, Lawrie B, Choi WS, Eres G, Levy J, Lee HN. Correlated oxide Dirac semimetal in the extreme quantum limit. SCIENCE ADVANCES 2021; 7:eabf9631. [PMID: 34524855 PMCID: PMC8443170 DOI: 10.1126/sciadv.abf9631] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 07/23/2021] [Indexed: 05/25/2023]
Abstract
Quantum materials (QMs) with strong correlation and nontrivial topology are indispensable to next-generation information and computing technologies. Exploitation of topological band structure is an ideal starting point to realize correlated topological QMs. Here, we report that strain-induced symmetry modification in correlated oxide SrNbO3 thin films creates an emerging topological band structure. Dirac electrons in strained SrNbO3 films reveal ultrahigh mobility (μmax ≈ 100,000 cm2/Vs), exceptionally small effective mass (m* ~ 0.04me), and nonzero Berry phase. Strained SrNbO3 films reach the extreme quantum limit, exhibiting a sign of fractional occupation of Landau levels and giant mass enhancement. Our results suggest that symmetry-modified SrNbO3 is a rare example of correlated oxide Dirac semimetals, in which strong correlation of Dirac electrons leads to the realization of a novel correlated topological QM.
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Affiliation(s)
- Jong Mok Ok
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | - Jie Zhang
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Sangmoon Yoon
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | - Eun Sang Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Hua Zhou
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Megan Briggeman
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | | | - Yun-Yi Pai
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | - Changhee Sohn
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Haoxiang Li
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Hu Miao
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | | | - Woo Seok Choi
- Department of Physics, Sungkyunkwan University, Suwon 16419, Korea
| | - Gyula Eres
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA 15260, USA
| | - Ho Nyung Lee
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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9
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Jin MJ, Um DS, Ohnishi K, Komori S, Stelmashenko N, Choe D, Yoo JW, Robinson JWA. Pure Spin Currents Driven by Colossal Spin-Orbit Coupling on Two-Dimensional Surface Conducting SrTiO 3. NANO LETTERS 2021; 21:6511-6517. [PMID: 34320314 DOI: 10.1021/acs.nanolett.1c01607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spin accumulation is generated by passing a charge current through a ferromagnetic layer and sensed by other ferromagnetic layers downstream. Pure spin currents can also be generated in which spin currents flow and are detected as a nonlocal resistance in which the charge current is diverted away from the voltage measurement point. Here, we report nonlocal spin-transport on two-dimensional surface-conducting SrTiO3 (STO) without a ferromagnetic spin-injector via the spin Hall effect (and inverse spin Hall effect). By applying magnetic fields to the Hall bars at different angles to the nonlocal spin-diffusion, we demonstrate an anisotropic spin-signal that is consistent with a Hanle precession of a pure spin current. We extract key transport parameters for surface-conducting STO, including: a spin Hall angle of γ ≈ (0.25 ± 0.05), a spin lifetime of τ ∼ 49 ps, and a spin diffusion length of λs ≈ (1.23 ± 0.7) μm at 2 K.
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Affiliation(s)
- Mi-Jin Jin
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Doo-Seung Um
- Department of Electrical Engineering, Sejong University, Seoul 05006, Republic of Korea
| | - Kohei Ohnishi
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Department of Physics, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan
| | - Sachio Komori
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Nadia Stelmashenko
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - Daeseong Choe
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea
| | - Jason W A Robinson
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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10
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Li D, Adamo C, Wang BY, Yoon H, Chen Z, Hong SS, Lu D, Cui Y, Hikita Y, Hwang HY. Stabilization of Sr 3Al 2O 6 Growth Templates for Ex Situ Synthesis of Freestanding Crystalline Oxide Membranes. NANO LETTERS 2021; 21:4454-4460. [PMID: 33989008 DOI: 10.1021/acs.nanolett.1c01194] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A new synthetic approach has recently been developed for the fabrication of freestanding crystalline perovskite oxide nanomembranes, which involves the epitaxial growth of a water-soluble sacrificial layer. By utilizing an ultrathin capping layer of SrTiO3, here we show that this sacrificial layer, as grown by pulsed laser deposition, can be stabilized in air and therefore be used as transferrable templates for ex situ epitaxial growth using other techniques. We find that the stability of these templates depends on the thickness of the capping layer. On these templates, freestanding superconducting SrTiO3 membranes were synthesized ex situ using molecular beam epitaxy, enabled by the lower growth temperature which preserves the sacrificial layer. This study paves the way for the synthesis of an expanded selection of freestanding oxide membranes and heterostructures with a wide variety of ex situ growth techniques.
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Affiliation(s)
- Danfeng Li
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong, China
| | - Carolina Adamo
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Bai Yang Wang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Hyeok Yoon
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Seung Sae Hong
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Di Lu
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
| | - Yi Cui
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, United States
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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11
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Rischau CW, Li Y, Fauqué B, Inoue H, Kim M, Bell C, Hwang HY, Kapitulnik A, Behnia K. Universal Bound to the Amplitude of the Vortex Nernst Signal in Superconductors. PHYSICAL REVIEW LETTERS 2021; 126:077001. [PMID: 33666461 DOI: 10.1103/physrevlett.126.077001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/05/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
A liquid of superconducting vortices generates a transverse thermoelectric response. This Nernst signal has a tail deep in the normal state due to superconducting fluctuations. Here, we present a study of the Nernst effect in two-dimensional heterostructures of Nb-doped strontium titanate (STO) and in amorphous MoGe. The Nernst signal generated by ephemeral Cooper pairs above the critical temperature has the magnitude expected by theory in STO. On the other hand, the peak amplitude of the vortex Nernst signal below T_{c} is comparable in both and in numerous other superconductors despite the large distribution of the critical temperature and the critical magnetic fields. In four superconductors belonging to different families, the maximum Nernst signal corresponds to an entropy per vortex per layer of ≈k_{B}ln2.
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Affiliation(s)
- Carl Willem Rischau
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
| | - Yuke Li
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
| | - Benoît Fauqué
- JEIP, USR 3573 CNRS, Collège de France, PSL Research University, 75005 Paris, France
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Minu Kim
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Christopher Bell
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Harold Y Hwang
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Aharon Kapitulnik
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - Kamran Behnia
- Laboratoire de Physique et d'Étude des Matériaux (ESPCI Paris-CNRS-Sorbonne Université), PSL Research University, 75005 Paris, France
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12
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Chen Z, Liu Z, Sun Y, Chen X, Liu Y, Zhang H, Li H, Zhang M, Hong S, Ren T, Zhang C, Tian H, Zhou Y, Sun J, Xie Y. Two-Dimensional Superconductivity at the LaAlO_{3}/KTaO_{3}(110) Heterointerface. PHYSICAL REVIEW LETTERS 2021; 126:026802. [PMID: 33512194 DOI: 10.1103/physrevlett.126.026802] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 07/15/2020] [Accepted: 12/17/2020] [Indexed: 06/12/2023]
Abstract
We report on the observation of a T_{c}∼0.9 K superconductivity at the interface between LaAlO_{3} film and the 5d transition metal oxide KTaO_{3}(110) single crystal. The interface shows a large anisotropy of the upper critical field, and its superconducting transition is consistent with a Berezinskii-Kosterlitz-Thouless transition. Both facts suggest that the superconductivity is two-dimensional (2D) in nature. The carrier density measured at 5 K is ∼7×10^{13} cm^{-2}. The superconducting layer thickness and coherence length are estimated to be ∼8 and ∼30 nm, respectively. Our result provides a new platform for the study of 2D superconductivity at oxide interfaces.
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Affiliation(s)
- Zheng Chen
- 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, China
| | - Zhongran Liu
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - 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, China
| | - Xiaoxin Chen
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, 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, China
| | - Hui Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Hekang Li
- 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, China
| | - Meng Zhang
- 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, China
| | - Siyuan Hong
- 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, China
| | - Tianshuang Ren
- 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, China
| | - Chao Zhang
- Instrumentation and Service Center for Physical Sciences, Westlake University, Hangzhou 310024, China
| | - He Tian
- Center of Electron Microscope, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China
| | - Yi Zhou
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
- Spintronics Institute, University of Jinan, Jinan, Shandong 250022, 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, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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13
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Ye M, Hu S, Zhu Y, Zhang Y, Ke S, Xie L, Zhang Y, Hu S, Zhang D, Luo Z, Gu M, He J, Zhang P, Zhang W, Chen L. Electric Polarization Switching on an Atomically Thin Metallic Oxide. NANO LETTERS 2021; 21:144-150. [PMID: 33306405 DOI: 10.1021/acs.nanolett.0c03417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Materials with reduced dimensions have been shown to host a wide variety of exotic properties and novel quantum states that often defy textbook wisdom. Polarization switching and metallic screening are well-known examples of mutually exclusive properties that cannot coexist in bulk solids. Here we report the fabrication of (SrRuO3)1/(BaTiO3)10 superlattices that exhibits reversible polarization switching in an atomically thin metallic layer. A multipronged investigation combining structural analyses, electrical measurements, and first-principles electronic structure calculations unravels the coexistence of two-dimensional (2D) metallicity in the SrRuO3 layer accompanied by the breaking of inversion symmetry, supporting electric polarization along the out-of-plane direction. Such a 2D ferroelectric-like metal paves a novel way to engineer a quantum multistate with unusual coexisting properties, such as ferroelectrics and metals, manipulated by external fields.
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Affiliation(s)
- Mao Ye
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Songbai Hu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuanmin Zhu
- Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yubo Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shanming Ke
- School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China
| | - Lin Xie
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuan Zhang
- School of Materials Science and Engineering, Xiangtan University, Hunan 411105, China
| | - Sixia Hu
- Core Research Facilities, Southern University of Science and Technology, Shenzhen 518055, China
| | - Dongwen Zhang
- College of Science, National University of Defense Technology, Hunan 410073, China
| | - Zhenlin Luo
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230026, China
| | - Meng Gu
- Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jiaqing He
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Peihong Zhang
- Department of Physics, State University of New York at Buffalo, Buffalo, New York 14260, United States
| | - Wenqing Zhang
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Lang Chen
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
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14
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Devarakonda A, Inoue H, Fang S, Ozsoy-Keskinbora C, Suzuki T, Kriener M, Fu L, Kaxiras E, Bell DC, Checkelsky JG. Clean 2D superconductivity in a bulk van der Waals superlattice. Science 2020; 370:231-236. [DOI: 10.1126/science.aaz6643] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 08/21/2020] [Indexed: 11/02/2022]
Abstract
Advances in low-dimensional superconductivity are often realized through improvements in material quality. Apart from a small group of organic materials, there is a near absence of clean-limit two-dimensional (2D) superconductors, which presents an impediment to the pursuit of numerous long-standing predictions for exotic superconductivity with fragile pairing symmetries. We developed a bulk superlattice consisting of the transition metal dichalcogenide (TMD) superconductor 2H-niobium disulfide (2H-NbS2) and a commensurate block layer that yields enhanced two-dimensionality, high electronic quality, and clean-limit inorganic 2D superconductivity. The structure of this material may naturally be extended to generate a distinct family of 2D superconductors, topological insulators, and excitonic systems based on TMDs with improved material properties.
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Affiliation(s)
- A. Devarakonda
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - H. Inoue
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - S. Fang
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - C. Ozsoy-Keskinbora
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - T. Suzuki
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - M. Kriener
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - L. Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - E. Kaxiras
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - D. C. Bell
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Center for Nanoscale Systems, Harvard University, Cambridge, MA 02138, USA
| | - J. G. Checkelsky
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Yang H, Zhou G, Zhu Y, Gong GM, Zhang Q, Liao M, Li Z, Ding C, Meng F, Rafique M, Wang H, Gu L, Zhang D, Wang L, Xue QK. Superconductivity above 28 K in single unit cell FeSe films interfaced with GaO 2-δ layer on NdGaO 3(1 1 0). Sci Bull (Beijing) 2019; 64:490-494. [PMID: 36659735 DOI: 10.1016/j.scib.2019.03.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 01/21/2023]
Affiliation(s)
- Haohao Yang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Guanyu Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Yuying Zhu
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Guan-Ming Gong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Qinghua Zhang
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Menghan Liao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Zheng Li
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cui Ding
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Fanqi Meng
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Mohsin Rafique
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Heng Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Lin Gu
- Laboratory for Advanced Materials & Electron Microscopy, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China
| | - Ding Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
| | - Lili Wang
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
| | - Qi-Kun Xue
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China; Collaborative Innovation Center of Quantum Matter, Beijing 100084, China.
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16
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Zeng M, Chen Y, Zhang E, Li J, Mendes RG, Sang X, Luo S, Ming W, Fu Y, Du MH, Zhang L, Parker DS, Unocic RR, Xiao K, Wang C, Zhang T, Xiao Y, Rümmeli MH, Xiu F, Fu L. Molecular Scaffold Growth of Two-Dimensional, Strong Interlayer-Bonding-Layered Materials. CCS CHEMISTRY 2019. [DOI: 10.31635/ccschem.019.20180003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Currently, most two-dimensional (2D) materials that are of interest to emergent applications have focused on van der Waals–layered materials (VLMs) because of the ease with which the layers can be separated (e.g., graphene). Strong interlayer-bonding-layered materials (SLMs) in general have not been thoroughly explored, and one of the most critical present issues is the huge challenge of their preparation, although their physicochemical property transformation should be richer than VLMs and deserves greater attention. MAX phases are a classical kind of SLM. However, limited to the strong interlayer bonding, their corresponding 2D counterparts have never been obtained, nor has there been investigation of their fundamental properties in the 2D limitation. Here, the authors develop a controllable bottom-up synthesis strategy for obtaining 2D SLMs single crystal through the design of a molecular scaffold with Mo 2GaC, which is a typical kind of MAX phase, as an example. The superconducting transitions of Mo 2GaC at the 2D limit are clearly inherited from the bulk, which is consistent with Berezinskii–Kosterlitz–Thouless behavior. The authors believe that their molecular scaffold strategy will allow the fabrication of other high-quality 2D SLMs single crystals, which will further expand the family of 2D materials and promote their future application.
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Affiliation(s)
- Mengqi Zeng
- 1College of Chemistry and Molecular Sciences, Wuhan University
| | - Yunxu Chen
- 1College of Chemistry and Molecular Sciences, Wuhan University
| | | | - Jiaxu Li
- 1College of Chemistry and Molecular Sciences, Wuhan University
| | | | - Xiahan Sang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory
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17
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Wang T, Wang X, Chen Z, Sun X, Wang P, Zheng X, Rong X, Yang L, Guo W, Wang D, Cheng J, Lin X, Li P, Li J, He X, Zhang Q, Li M, Zhang J, Yang X, Xu F, Ge W, Zhang X, Shen B. High-Mobility Two-Dimensional Electron Gas at InGaN/InN Heterointerface Grown by Molecular Beam Epitaxy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1800844. [PMID: 30250812 PMCID: PMC6145405 DOI: 10.1002/advs.201800844] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Indexed: 05/27/2023]
Abstract
Due to the intrinsic spontaneous and piezoelectric polarization effect, III-nitride semiconductor heterostructures are promising candidates for generating 2D electron gas (2DEG) system. Among III-nitrides, InN is predicted to be the best conductive-channel material because its electrons have the smallest effective mass and it exhibits large band offsets at the heterointerface of GaN/InN or AlN/InN. Until now, that prediction has remained theoretical, due to a giant gap between the optimal growth windows of InN and GaN, and the difficult epitaxial growth of InN in general. The experimental realization of 2DEG at an InGaN/InN heterointerface grown by molecular beam epitaxy is reported here. The directly probed electron mobility and the sheet electron density of the InGaN/InN heterostructure are determined by Hall-effect measurements at room temperature to be 2.29 × 103 cm2 V-1 s-1 and 2.14 × 1013 cm-2, respectively, including contribution from the InN bottom layer. The Shubnikov-de Haas results at 3 K confirm that the 2DEG has an electron density of 3.30 × 1012 cm-2 and a quantum mobility of 1.48 × 103 cm2 V-1 s-1. The experimental observations of 2DEG at the InGaN/InN heterointerface have paved the way for fabricating higher-speed transistors based on an InN channel.
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Affiliation(s)
- Tao Wang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Xinqiang Wang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
- Collaborative Innovation Center of Quantum MatterBeijing100871P. R. China
| | - Zhaoying Chen
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Xiaoxiao Sun
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Ping Wang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Xiantong Zheng
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Xin Rong
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Liuyun Yang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Weiwei Guo
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Ding Wang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
- Microsystem & Terahertz Research CenterChina Academy of Engineering Physics (CAEP)Chengdu610200P. R. China
| | - Jianpeng Cheng
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Xi Lin
- Collaborative Innovation Center of Quantum MatterBeijing100871P. R. China
| | - Peng Li
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Jun Li
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Xin He
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Qiang Zhang
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Mo Li
- Microsystem & Terahertz Research CenterChina Academy of Engineering Physics (CAEP)Chengdu610200P. R. China
| | - Jian Zhang
- Microsystem & Terahertz Research CenterChina Academy of Engineering Physics (CAEP)Chengdu610200P. R. China
| | - Xuelin Yang
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Fujun Xu
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Weikun Ge
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
| | - Xixiang Zhang
- King Abdullah University of Science and TechnologyDivision of Physical Science and EngineeringThuwal23955–6900Kingdom of Saudi Arabia
| | - Bo Shen
- State Key Laboratory of Artificial Microstructure and Mesoscopic PhysicsSchool of PhysicsPeking UniversityBeijing100871P. R. China
- Collaborative Innovation Center of Quantum MatterBeijing100871P. R. China
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18
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Yan R, Khalsa G, Vishwanath S, Han Y, Wright J, Rouvimov S, Katzer DS, Nepal N, Downey BP, Muller DA, Xing HG, Meyer DJ, Jena D. GaN/NbN epitaxial semiconductor/superconductor heterostructures. Nature 2018. [PMID: 29516996 DOI: 10.1038/nature25768] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Epitaxy is a process by which a thin layer of one crystal is deposited in an ordered fashion onto a substrate crystal. The direct epitaxial growth of semiconductor heterostructures on top of crystalline superconductors has proved challenging. Here, however, we report the successful use of molecular beam epitaxy to grow and integrate niobium nitride (NbN)-based superconductors with the wide-bandgap family of semiconductors-silicon carbide, gallium nitride (GaN) and aluminium gallium nitride (AlGaN). We apply molecular beam epitaxy to grow an AlGaN/GaN quantum-well heterostructure directly on top of an ultrathin crystalline NbN superconductor. The resulting high-mobility, two-dimensional electron gas in the semiconductor exhibits quantum oscillations, and thus enables a semiconductor transistor-an electronic gain element-to be grown and fabricated directly on a crystalline superconductor. Using the epitaxial superconductor as the source load of the transistor, we observe in the transistor output characteristics a negative differential resistance-a feature often used in amplifiers and oscillators. Our demonstration of the direct epitaxial growth of high-quality semiconductor heterostructures and devices on crystalline nitride superconductors opens up the possibility of combining the macroscopic quantum effects of superconductors with the electronic, photonic and piezoelectric properties of the group III/nitride semiconductor family.
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Affiliation(s)
- Rusen Yan
- School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Guru Khalsa
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Suresh Vishwanath
- School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Yimo Han
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
| | - John Wright
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA
| | - Sergei Rouvimov
- Department of Electrical Engineering, University of Notre Dame, Indiana 46556, USA
| | - D Scott Katzer
- Electronics Science and Technology Division, US Naval Research Laboratory, Washington DC 20375, USA
| | - Neeraj Nepal
- Electronics Science and Technology Division, US Naval Research Laboratory, Washington DC 20375, USA
| | - Brian P Downey
- Electronics Science and Technology Division, US Naval Research Laboratory, Washington DC 20375, USA
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.,Kavli Institute for Nanoscale Science, Cornell University, Ithaca, New York 14853, USA
| | - Huili G Xing
- School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA.,Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA.,Kavli Institute for Nanoscale Science, Cornell University, Ithaca, New York 14853, USA
| | - David J Meyer
- Electronics Science and Technology Division, US Naval Research Laboratory, Washington DC 20375, USA
| | - Debdeep Jena
- School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA.,Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA.,Kavli Institute for Nanoscale Science, Cornell University, Ithaca, New York 14853, USA
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19
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Chen L, Li J, Tang Y, Pai YY, Chen Y, Pryds N, Irvin P, Levy J. Extreme Reconfigurable Nanoelectronics at the CaZrO 3 /SrTiO 3 Interface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1801794. [PMID: 29962024 DOI: 10.1002/adma.201801794] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/10/2018] [Indexed: 06/08/2023]
Abstract
Complex oxide heterostructures have fascinating emergent properties that originate from the properties of the bulk constituents as well as from dimensional confinement. The conductive behavior of the polar/nonpolar LaAlO3 /SrTiO3 interface can be reversibly switched using conductive atomic force microscopy (c-AFM) lithography, enabling a wide range of devices and physics to be explored. Here, extreme nanoscale control over the CaZrO3 /SrTiO3 (CZO/STO) interface, which is formed from two materials that are both nonpolar, is reported. Nanowires with measured widths as narrow as 1.2 nm are realized at the CZO/STO interface at room temperature by c-AFM lithography. These ultrathin nanostructures have spatial dimensions at room temperature that are comparable to single-walled carbon nanotubes, and hold great promise for alternative oxide-based nanoelectronics, as well as offer new opportunities to investigate the electronic structure of the complex oxide interfaces. The cryogenic properties of devices constructed from quasi-1D channels, tunnel barriers, and planar gates exhibit gate-tunable superconductivity, quantum oscillations, electron pairing outside of the superconducting regime, and quasi-ballistic transport. This newly demonstrated ability to control the metal-insulator transition at nonpolar oxide interface greatly expands the class of materials whose behavior can be patterned and reconfigured at extreme nanoscale dimensions.
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Affiliation(s)
- Lu Chen
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Jianan Li
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Yuhe Tang
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, Roskilde, 4000, Denmark
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, Roskilde, 4000, Denmark
| | - Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Jeremy Levy
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
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20
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Aslam M, Singh CK, Das S, Kumar R, Datta S, Halder S, Gayen S, Kabir M, Sheet G. Large enhancement of superconductivity in Zr point contacts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:255002. [PMID: 29708502 DOI: 10.1088/1361-648x/aac154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
For certain complex superconducting systems, the superconducting properties get enhanced under mesoscopic point contacts made of elemental non-superconducting metals. However, understanding of the mechanism through which such contact induced local enhancement of superconductivity happens has been limited due to the complex nature of such compounds. In this paper we present a large enhancement of superconducting transition temperature T c and superconducting energy gap Δ in a simple elemental superconductor Zr. While bulk Zr shows a critical temperature around 0.6 K, superconductivity survives at Ag/Zr and Pt/Zr point contacts up to 3 K with a corresponding five-fold enhancement of Δ. Further, the first-principles calculations on a model system provide useful insights. We show that the enhancement in superconducting properties can be attributed to a modification in the electron-phonon coupling accompanied by an enhancement of the density of states which involves the appearance of a new electron band at the Ag/Zr interfaces.
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Affiliation(s)
- Mohammad Aslam
- Department of Physical Sciences, Indian Institute of Science Education and Research, Mohali 140306, India
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21
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Double quantum criticality in superconducting tin arrays-graphene hybrid. Nat Commun 2018; 9:2159. [PMID: 29867112 PMCID: PMC5986781 DOI: 10.1038/s41467-018-04606-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 04/24/2018] [Indexed: 11/11/2022] Open
Abstract
Two magnetic-field-induced quantum critical behaviors were recently discovered in two dimensional electron gas (2DEG) at LaTiO3/SrTiO3 interface and interpreted by disordered superconducting puddles coupled through 2DEG. In this scenario, the 2DEG is proposed to undergo a spontaneous phase separation and breaks up into locally superconducting puddles in a metallic matrix. However, as the inhomogeneous superconducting 2DEG is only illative, this proposal still lacks the direct experimental demonstration. Here, we artificially construct superconducting puddles-2DEG hybrid system by depositing tin nanoislands array on single crystalline monolayer graphene, where the two quantum critical behaviors are reproduced. Through the finite-size scaling analysis on magnetoresistivity, we show that the two quantum critical behaviors result from the intra-island and inter-island phase coherence, respectively, which are further illustrated by the phase diagram. This work provides a platform to study superconducting quantum phase transitions in a 2D system and helps to integrate superconducting devices into semiconductor technology. Two quantum critical behaviors appear in a two dimensional electron gas (2DEG) but its origin remains to be attested. Here, Sun et al. construct superconducting puddles-2DEG hybrid system by depositing tin nano-islands array on monolayer graphene where the two quantum critical behaviors are reproduced, suggesting the formation of inhomogeneous superconducting 2DEG.
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22
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Falson J, Kawasaki M. A review of the quantum Hall effects in MgZnO/ZnO heterostructures. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:056501. [PMID: 29353814 DOI: 10.1088/1361-6633/aaa978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This review visits recent experimental efforts on high mobility two-dimensional electron systems (2DES) hosted at the Mg x Zn[Formula: see text]O/ZnO heterointerface. We begin with the growth of these samples, and highlight the key characteristics of ozone-assisted molecular beam epitaxy required for their production. The transport characteristics of these structures are found to rival that of traditional semiconductor material systems, as signified by the high electron mobility ([Formula: see text] cm2 Vs-1) and rich quantum Hall features. Owing to a large effective mass and small dielectric constant, interaction effects are an order of magnitude stronger in comparison with the well studied GaAs-based 2DES. The strong correlation physics results in robust Fermi-liquid renormalization of the effective mass and spin susceptibility of carriers, which in turn dictates the parameter space for the quantum Hall effect. Finally, we explore the quantum Hall effect with a particular emphasis on the spin degree of freedom of carriers, and how their large spin splitting allows control of the ground states encountered at ultra-low temperatures within the fractional quantum Hall regime. We discuss in detail the physics of even-denominator fractional quantum Hall states, whose observation and underlying character remain elusive and exotic.
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Affiliation(s)
- Joseph Falson
- Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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23
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Veit MJ, Arras R, Ramshaw BJ, Pentcheva R, Suzuki Y. Nonzero Berry phase in quantum oscillations from giant Rashba-type spin splitting in LaTiO 3/SrTiO 3 heterostructures. Nat Commun 2018; 9:1458. [PMID: 29654231 PMCID: PMC5899139 DOI: 10.1038/s41467-018-04014-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 03/26/2018] [Indexed: 11/17/2022] Open
Abstract
The manipulation of the spin degrees of freedom in a solid has been of fundamental and technological interest recently for developing high-speed, low-power computational devices. There has been much work focused on developing highly spin-polarized materials and understanding their behavior when incorporated into so-called spintronic devices. These devices usually require spin splitting with magnetic fields. However, there is another promising strategy to achieve spin splitting using spatial symmetry breaking without the use of a magnetic field, known as Rashba-type splitting. Here we report evidence for a giant Rashba-type splitting at the interface of LaTiO3 and SrTiO3. Analysis of the magnetotransport reveals anisotropic magnetoresistance, weak anti-localization and quantum oscillation behavior consistent with a large Rashba-type splitting. It is surprising to find a large Rashba-type splitting in 3d transition metal oxide-based systems such as the LaTiO3/SrTiO3 interface, but it is promising for the development of a new kind of oxide-based spintronics. Rashba-type splitting is an effective way to manipulate the spin degrees of freedom in a solid without external magnetic field. Here, the authors demonstrate a strong Rashba-type splitting at the interface of LaTiO3 and SrTiO3 which is promising for the development of oxide-based spintronics.
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Affiliation(s)
- M J Veit
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA.
| | - R Arras
- CEMES, University of Toulouse, CNRS, UPS, 29, rue Jeanne Marvig, 31055, Toulouse, France
| | - B J Ramshaw
- Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.,Laboratory for Atomic and Solid State Physics, Cornell University, Ithaca, NY, 14853, USA
| | - R Pentcheva
- Department of Physics and Center for Nanointegration (CENIDE), University of Duisburg-Essen, Lotharstrasse 1, 47057, Duisburg, Germany
| | - Y Suzuki
- Department of Applied Physics and Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, 94305, USA
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24
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Abstract
The nature of superconductivity in the dilute semiconductor SrTiO3 has remained an open question for more than 50 y. The extremely low carrier densities ([Formula: see text]-[Formula: see text] cm-3) at which superconductivity occurs suggest an unconventional origin of superconductivity outside of the adiabatic limit on which the Bardeen-Cooper-Schrieffer (BCS) and Migdal-Eliashberg (ME) theories are based. We take advantage of a newly developed method for engineering band alignments at oxide interfaces and access the electronic structure of Nb-doped SrTiO3, using high-resolution tunneling spectroscopy. We observe strong coupling to the highest-energy longitudinal optic (LO) phonon branch and estimate the doping evolution of the dimensionless electron-phonon interaction strength ([Formula: see text]). Upon cooling below the superconducting transition temperature ([Formula: see text]), we observe a single superconducting gap corresponding to the weak-coupling limit of BCS theory, indicating an order of magnitude smaller coupling ([Formula: see text]). These results suggest that despite the strong normal state interaction with electrons, the highest LO phonon does not provide a dominant contribution to pairing. They further demonstrate that SrTiO3 is an ideal system to probe superconductivity over a wide range of carrier density, adiabatic parameter, and electron-phonon coupling strength.
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25
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Pai YY, Tylan-Tyler A, Irvin P, Levy J. Physics of SrTiO 3-based heterostructures and nanostructures: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:036503. [PMID: 29424362 DOI: 10.1088/1361-6633/aa892d] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
This review provides a summary of the rich physics expressed within SrTiO3-based heterostructures and nanostructures. The intended audience is researchers who are working in the field of oxides, but also those with different backgrounds (e.g., semiconductor nanostructures). After reviewing the relevant properties of SrTiO3 itself, we will then discuss the basics of SrTiO3-based heterostructures, how they can be grown, and how devices are typically fabricated. Next, we will cover the physics of these heterostructures, including their phase diagram and coupling between the various degrees of freedom. Finally, we will review the rich landscape of quantum transport phenomena, as well as the devices that elicit them.
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Affiliation(s)
- Yun-Yi Pai
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States of America. Pittsburgh Quantum Institute, Pittsburgh, PA 15260, United States of America
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26
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Mattoni G, Baek DJ, Manca N, Verhagen N, Groenendijk DJ, Kourkoutis LF, Filippetti A, Caviglia AD. Insulator-to-Metal Transition at Oxide Interfaces Induced by WO 3 Overlayers. ACS APPLIED MATERIALS & INTERFACES 2017; 9:42336-42343. [PMID: 29111647 DOI: 10.1021/acsami.7b13202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Interfaces between complex oxides constitute a unique playground for two-dimensional electron systems (2DESs), where superconductivity and magnetism can arise from combinations of bulk insulators. The 2DES at the LaAlO3/SrTiO3 interface is one of the most studied in this regard, and its origin is determined by the polar field in LaAlO3 as well as by the presence of point defects, like oxygen vacancies and intermixed cations. These defects usually reside in the conduction channel and are responsible for a decrease of the electronic mobility. In this work, we use an amorphous WO3 overlayer to obtain a high-mobility 2DES in WO3/LaAlO3/SrTiO3 heterostructures. The studied system shows a sharp insulator-to-metal transition as a function of both LaAlO3 and WO3 layer thickness. Low-temperature magnetotransport reveals a strong magnetoresistance reaching 900% at 10 T and 1.5 K, the presence of multiple conduction channels with carrier mobility up to 80 000 cm2 V-1 s-1, and quantum oscillations of conductance.
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Affiliation(s)
- Giordano Mattoni
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | | | - Nicola Manca
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Nils Verhagen
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | - Dirk J Groenendijk
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
| | | | - Alessio Filippetti
- Dipartimento di Fisica, Università di Cagliari , Cagliari, Monserrato 09042-I, Italy
- CNR-IOM, Istituto Officina dei Materiali, Cittadella Universitaria , Cagliari, Monserrato 09042-I, Italy
| | - Andrea D Caviglia
- Kavli Institute of Nanoscience, Delft University of Technology , 2628 CJ Delft, The Netherlands
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27
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Moon EJ, He Q, Ghosh S, Kirby BJ, Pantelides ST, Borisevich AY, May SJ. Structural "δ Doping" to Control Local Magnetization in Isovalent Oxide Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:197204. [PMID: 29219521 DOI: 10.1103/physrevlett.119.197204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Indexed: 06/07/2023]
Abstract
Modulation and δ-doping strategies, in which atomically thin layers of charged dopants are precisely deposited within a heterostructure, have played enabling roles in the discovery of new physical behavior in electronic materials. Here, we demonstrate a purely structural "δ-doping" strategy in complex oxide heterostructures, in which atomically thin manganite layers are inserted into an isovalent manganite host, thereby modifying the local rotations of corner-connected MnO_{6} octahedra. Combining scanning transmission electron microscopy, polarized neutron reflectometry, and density functional theory, we reveal how local magnetic exchange interactions are enhanced within the spatially confined regions of suppressed octahedral rotations. The combined experimental and theoretical results illustrate the potential to utilize noncharge-based approaches to "doping" in order to enhance or suppress functional properties within spatially confined regions of oxide heterostructures.
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Affiliation(s)
- E J Moon
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Q He
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S Ghosh
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
- SRM Research Institute and Department of Physics and Nanotechnology, SRM University, Kattankulathur, Tamil Nadu 603203, India
| | - B J Kirby
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - S T Pantelides
- Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235, USA
| | - A Y Borisevich
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S J May
- Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
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28
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Okada Y, Shiau SY, Chang TR, Chang G, Kobayashi M, Shimizu R, Jeng HT, Shiraki S, Kumigashira H, Bansil A, Lin H, Hitosugi T. Quasiparticle Interference on Cubic Perovskite Oxide Surfaces. PHYSICAL REVIEW LETTERS 2017; 119:086801. [PMID: 28952762 DOI: 10.1103/physrevlett.119.086801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Indexed: 06/07/2023]
Abstract
We report the observation of coherent surface states on cubic perovskite oxide SrVO_{3}(001) thin films through spectroscopic-imaging scanning tunneling microscopy. A direct link between the observed quasiparticle interference patterns and the formation of a d_{xy}-derived surface state is supported by first-principles calculations. We show that the apical oxygens on the topmost VO_{2} plane play a critical role in controlling the coherent surface state via modulating orbital state.
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Affiliation(s)
- Yoshinori Okada
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Shiue-Yuan Shiau
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Tay-Rong Chang
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
| | - Guoqing Chang
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Masaki Kobayashi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Ryota Shimizu
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Horng-Tay Jeng
- Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Susumu Shiraki
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
| | - Hiroshi Kumigashira
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801, Japan
| | - Arun Bansil
- Department of Physics, Northeastern University, Boston, Massachusetts 02115, USA
| | - Hsin Lin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117546, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
| | - Taro Hitosugi
- Advanced Institute for Materials Research (AIMR), Tohoku University, Sendai 980-8577, Japan
- Department of Applied Chemistry, Tokyo Institute of Technology, Tokyo 152-8552, Japan
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29
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Bisri SZ, Shimizu S, Nakano M, Iwasa Y. Endeavor of Iontronics: From Fundamentals to Applications of Ion-Controlled Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1607054. [PMID: 28582588 DOI: 10.1002/adma.201607054] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 02/16/2017] [Indexed: 05/28/2023]
Abstract
Iontronics is a newly emerging interdisciplinary concept which bridges electronics and ionics, covering electrochemistry, solid-state physics, electronic engineering, and biological sciences. The recent developments of electronic devices are highlighted, based on electric double layers formed at the interface between ionic conductors (but electronically insulators) and various electronic conductors including organics and inorganics (oxides, chalcogenide, and carbon-based materials). Particular attention is devoted to electric-double-layer transistors (EDLTs), which are producing a significant impact, particularly in electrical control of phase transitions, including superconductivity, which has been difficult or impossible in conventional all-solid-state electronic devices. Besides that, the current state of the art and the future challenges of iontronics are also reviewed for many applications, including flexible electronics, healthcare-related devices, and energy harvesting.
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Affiliation(s)
- Satria Zulkarnaen Bisri
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Sunao Shimizu
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
| | - Masaki Nakano
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
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30
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Shin YJ, Kim Y, Kang SJ, Nahm HH, Murugavel P, Kim JR, Cho MR, Wang L, Yang SM, Yoon JG, Chung JS, Kim M, Zhou H, Chang SH, Noh TW. Interface Control of Ferroelectricity in an SrRuO 3 /BaTiO 3 /SrRuO 3 Capacitor and its Critical Thickness. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1602795. [PMID: 28256752 DOI: 10.1002/adma.201602795] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 12/21/2016] [Indexed: 06/06/2023]
Abstract
The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO3 /BaTiO3 /SrRuO3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO2 -BaO and SrO-TiO2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.
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Affiliation(s)
- Yeong Jae Shin
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yoonkoo Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sung-Jin Kang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Ho-Hyun Nahm
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Pattukkannu Murugavel
- Department of Physics, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Jeong Rae Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Myung Rae Cho
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Lingfei Wang
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sang Mo Yang
- Department of Physics, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Jong-Gul Yoon
- Department of Physics, University of Suwon, Hwaseong, Gyunggi-do, 18323, Republic of Korea
| | - Jin-Seok Chung
- Department of Physics, Soongsil University, Seoul, 06978, Republic of Korea
| | - Miyoung Kim
- Department of Materials Science and Engineering and Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Hua Zhou
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Seo Hyoung Chang
- Department of Physics, Pukyong National University, Busan, 48513, Republic of Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea
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31
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Jeong JS, Topsakal M, Xu P, Jalan B, Wentzcovitch RM, Mkhoyan KA. A New Line Defect in NdTiO 3 Perovskite. NANO LETTERS 2016; 16:6816-6822. [PMID: 27736081 DOI: 10.1021/acs.nanolett.6b02532] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Perovskite oxides form an eclectic class of materials owing to their structural flexibility in accommodating cations of different sizes and valences. They host well-known point and planar defects, but so far no line defect has been identified other than dislocations. Using analytical scanning transmission electron microscopy (STEM) and ab initio calculations, we have detected and characterized the atomic and electronic structures of a novel line defect in NdTiO3 perovskite. It appears in STEM images as a perovskite cell rotated by 45°. It consists of self-organized Ti-O vacancy lines replaced by Nd columns surrounding a central Ti-O octahedral chain containing Ti4+ ions, as opposed to Ti3+ in the host. The distinct Ti valence in this line defect introduces the possibility of engineering exotic conducting properties in a single preferred direction and tailoring novel desirable functionalities in this Mott insulator.
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Affiliation(s)
- Jong Seok Jeong
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Mehmet Topsakal
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Peng Xu
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Bharat Jalan
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Renata M Wentzcovitch
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - K Andre Mkhoyan
- Department of Chemical Engineering and Materials Science, University of Minnesota , Minneapolis, Minnesota 55455, United States
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32
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Baiutti F, Gregori G, Wang Y, Suyolcu YE, Cristiani G, van Aken PA, Maier J, Logvenov G. Cationic Redistribution at Epitaxial Interfaces in Superconducting Two-Dimensionally Doped Lanthanum Cuprate Films. ACS APPLIED MATERIALS & INTERFACES 2016; 8:27368-27375. [PMID: 27648928 DOI: 10.1021/acsami.6b09739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The exploration of interface effects in complex oxide heterostructures has led to the discovery of novel intriguing phenomena in recent years and has opened the path toward the precise tuning of material properties at the nanoscale. One recent example is space-charge superconductivity. Among the complex range of effects which may arise from phase interaction, a crucial role is played by cationic intermixing, which defines the final chemical composition of the interface. In this work, we performed a systematic study on the local cationic redistribution of two-dimensionally doped lanthanum cuprate films grown by oxide molecular beam epitaxy, in which single LaO layers in the epitaxial crystal structure were substituted by layers of differently sized and charged dopants (Ca, Sr, Ba, and Dy). In such a model system, in which the dopant undergoes an asymmetric redistribution across the interface, the evolution of the cationic concentration profile can be effectively tracked by means of atomically resolved imaging and spectroscopic methods. This allowed for the investigation of the impact of the dopant chemistry (ionic size and charge) and of the growth conditions (temperature) on the final superconducting and structural properties. A qualitative model for interface cationic intermixing, based on thermodynamic considerations, is proposed. This work highlights the key role which cationic redistribution may have in the definition of the final interface properties and represents a further step forward the realization of heterostructures with improved quality.
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Affiliation(s)
- Federico Baiutti
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Giuliano Gregori
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Yi Wang
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Y Eren Suyolcu
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Georg Cristiani
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Peter A van Aken
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Joachim Maier
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Gennady Logvenov
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
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Matsubara Y, Takahashi KS, Bahramy MS, Kozuka Y, Maryenko D, Falson J, Tsukazaki A, Tokura Y, Kawasaki M. Observation of the quantum Hall effect in δ-doped SrTiO3. Nat Commun 2016; 7:11631. [PMID: 27228903 PMCID: PMC4894966 DOI: 10.1038/ncomms11631] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 04/15/2016] [Indexed: 11/09/2022] Open
Abstract
The quantum Hall effect is a macroscopic quantum phenomenon in a two-dimensional electron system. The two-dimensional electron system in SrTiO3 has sparked a great deal of interest, mainly because of the strong electron correlation effects expected from the 3d orbitals. Here we report the observation of the quantum Hall effect in a dilute La-doped SrTiO3-two-dimensional electron system, fabricated by metal organic molecular-beam epitaxy. The quantized Hall plateaus are found to be solely stemming from the low Landau levels with even integer-filling factors, ν=4 and 6 without any contribution from odd ν's. For ν=4, the corresponding plateau disappears on decreasing the carrier density. Such peculiar behaviours are proposed to be due to the crossing between the Landau levels originating from the two subbands composed of d orbitals with different effective masses. Our findings pave a way to explore unprecedented quantum phenomena in d-electron systems.
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Affiliation(s)
- Y. Matsubara
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Institute for Materials Research, Tohoku University, Sendai 908-8577, Japan
| | - K. S. Takahashi
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Chiyoda-ku, Tokyo 102-0075, Japan
| | - M. S. Bahramy
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan
| | - Y. Kozuka
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan
| | - D. Maryenko
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
| | - J. Falson
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan
| | - A. Tsukazaki
- Institute for Materials Research, Tohoku University, Sendai 908-8577, Japan
| | - Y. Tokura
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan
| | - M. Kawasaki
- RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan
- Department of Applied Physics and Quantum Phase Electronics Center, University of Tokyo, Tokyo 113-8656, Japan
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34
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Moon SY, Moon CW, Chang HJ, Kim T, Kang CY, Choi HJ, Kim JS, Baek SH, Jang HW. Thermal stability of 2DEG at amorphous LaAlO 3/crystalline SrTiO 3 heterointerfaces. NANO CONVERGENCE 2016; 3:7. [PMID: 28191417 PMCID: PMC5271142 DOI: 10.1186/s40580-016-0067-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/10/2016] [Indexed: 06/06/2023]
Abstract
At present, the generation of heterostructures with two dimensional electron gas (2DEG) in amorphous LaAlO3 (a-LAO)/SrTiO3 (STO) has been achieved. Herein, we analysed thermal stability of 2DEG at a-LAO/STO interfaces in comparison with 2DEG at crystalline LaAlO3 (c-LAO)/STO interfaces. To create 2DEG at LAO/STO interface, regardless of growing temperature from 25 to 700 °C, we found that environment with oxygen deficient during the deposition of LAO overlayer is essentially required. That indicates that the oxygen-poor condition in the system is more essential than the crystalline nature of LAO layer. 2DEG at a-LAO/STO interface is depleted upon ex situ annealing at 300 °C under 300 Torr of oxygen pressure, while that in c-LAO/STO interface is still maintained. Our result suggests that the LAO overlayer crystallinity critically affects the thermal-annealing-induced depletion of 2DEG at a-LAO/STO interface rather than the generation of 2DEG. We clearly provide that amorphous TiOx can efficiently prevent the thermal degradation of 2DEG at the a-LAO/STO interface, which gives a cornerstone for achieving thermal-stable 2DEG at a-LAO/STO interface.
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Affiliation(s)
- Seon Young Moon
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 136-791 Republic of Korea
- Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Cheon Woo Moon
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 151-744 Republic of Korea
| | - Hye Jung Chang
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 136-791 Republic of Korea
- Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-350 Republic of Korea
| | - Taemin Kim
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 151-744 Republic of Korea
| | - Chong-Yun Kang
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 136-791 Republic of Korea
- Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-350 Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 136-701 Republic of Korea
| | - Heon-Jin Choi
- Department of Materials Science and Engineering, Yonsei University, Seoul, 120-749 Republic of Korea
| | - Jin-Sang Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 136-791 Republic of Korea
| | - Seung-Hyub Baek
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 136-791 Republic of Korea
- Department of Nanomaterials Science and Technology, Korea University of Science and Technology, Daejeon, 305-350 Republic of Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 151-744 Republic of Korea
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35
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O'Sullivan M, Hadermann J, Dyer MS, Turner S, Alaria J, Manning TD, Abakumov AM, Claridge JB, Rosseinsky MJ. Interface control by chemical and dimensional matching in an oxide heterostructure. Nat Chem 2016; 8:347-53. [DOI: 10.1038/nchem.2441] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/16/2015] [Indexed: 11/09/2022]
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36
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Renshaw Wang X, Sun L, Huang Z, Lü WM, Motapothula M, Annadi A, Liu ZQ, Zeng SW, Venkatesan T, Ariando. Parallel charge sheets of electron liquid and gas in La0.5Sr0.5TiO3/SrTiO3 heterostructures. Sci Rep 2015; 5:18282. [PMID: 26669575 PMCID: PMC4680910 DOI: 10.1038/srep18282] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 09/14/2015] [Indexed: 12/05/2022] Open
Abstract
We show here a new phenomenon in La0.5Sr0.5TiO3/SrTiO3 (LSTO/STO) heterostructures; that is a coexistence of three-dimensional electron liquid (3DEL) and 2D electron gas (2DEG), separated by an intervening insulating LSTO layer. The two types of carriers were revealed through multi-channel analysis of the evolution of nonlinear Hall effect as a function of film thickness, temperature and back gate voltage. We demonstrate that the 3D electron originates from La doping in LSTO film and the 2D electron at the surface of STO is due to the polar field in the intervening insulating layer. As the film thickness is reduced below a critical thickness of 6 unit cells (uc), an abrupt metal-to-insulator transition (MIT) occurs without an intermediate semiconducting state. The properties of the LSTO layer grown on different substrates suggest that the insulating phase of the intervening layer is a result of interface strain induced by the lattice mismatch between the film and substrate. Further, by fitting the magnetoresistance (MR) curves, the 6 unit cell thick LSTO is shown to exhibit spin-orbital coupling. These observations point to new functionalities, in addition to magnetism and superconductivity in STO-based systems, which could be exploited in a multifunctional context.
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Affiliation(s)
- X Renshaw Wang
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore.,Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. BOX 217, 7500 AE Enschede, The Netherlands
| | - L Sun
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore
| | - Z Huang
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - W M Lü
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - M Motapothula
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - A Annadi
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - Z Q Liu
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - S W Zeng
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore
| | - T Venkatesan
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore.,National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
| | - Ariando
- NUSNNI-Nanocore, National University of Singapore, 117411 Singapore.,Department of Physics, National University of Singapore, 117542 Singapore.,National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS), 28 Medical Drive, Singapore 117456, Singapore
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37
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Kobayashi S, Mizumukai Y, Ohnishi T, Shibata N, Ikuhara Y, Yamamoto T. High Electron Mobility of Nb-Doped SrTiO₃ Films Stemming from Rod-Type Sr Vacancy Clusters. ACS NANO 2015; 9:10769-10777. [PMID: 26487067 DOI: 10.1021/acsnano.5b05720] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Achieving high electron mobility in SrTiO3 films is of significant interest, particularly in relation to technological applications such as oxide semiconductors, field-induced superconductors, and thermoelectric generators. One route to achieving high electron mobility is growth of high quality SrTiO3 films with low defect concentrations. Another approach for mobility enhancement is applying a strain to the crystal. However, the maximum mobilities obtainable by these approaches are limited both by external and internal factors (currently available fabrication techniques, and maximum crystal strain, for example). In this paper, we demonstrate a unique crystal engineering approach to alter the strain in Nb-doped SrTiO3 films based on the deliberate introduction of Sr vacancy clusters. Nb-doped SrTiO3 films produced in this manner are found to exhibit remarkably enhanced electron mobilities (exceeding 53,000 cm(2) V(-1) s(-1)). This method of defect engineering is expected to enable tuning and enhancement of electron mobilities not only in SrTiO3 films, but also in thin films and bulk crystals of other perovskite-type materials.
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Affiliation(s)
- Shunsuke Kobayashi
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
| | - Yuki Mizumukai
- Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan
| | - Tsuyoshi Ohnishi
- National Institute for Materials Science , Tsukuba, Ibaraki 305-0044, Japan
| | - Naoya Shibata
- Institute of Engineering Innovation, The University of Tokyo , Bunkyo, Tokyo 113-8656, Japan
- PRESTO, Japan Science and Technology Agency , Saitama 332-0012, Japan
| | - Yuichi Ikuhara
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
- Institute of Engineering Innovation, The University of Tokyo , Bunkyo, Tokyo 113-8656, Japan
| | - Takahisa Yamamoto
- Nanostructures Research Laboratory, Japan Fine Ceramics Center , Atsuta, Nagoya 456-8587, Japan
- Department of Advanced Materials Science, The University of Tokyo , Kashiwa, Chiba 277-8561, Japan
- Department of Quantum Engineering, Nagoya University , Chikusa, Nagoya 464-8603, Japan
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38
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Xu C, Wang L, Liu Z, Chen L, Guo J, Kang N, Ma XL, Cheng HM, Ren W. Large-area high-quality 2D ultrathin Mo2C superconducting crystals. NATURE MATERIALS 2015; 14:1135-41. [PMID: 26280223 DOI: 10.1038/nmat4374] [Citation(s) in RCA: 452] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 07/01/2015] [Indexed: 05/17/2023]
Abstract
Transition metal carbides (TMCs) are a large family of materials with many intriguing properties and applications, and high-quality 2D TMCs are essential for investigating new physics and properties in the 2D limit. However, the 2D TMCs obtained so far are chemically functionalized, defective nanosheets having maximum lateral dimensions of ∼10 μm. Here we report the fabrication of large-area high-quality 2D ultrathin α-Mo2C crystals by chemical vapour deposition (CVD). The crystals are a few nanometres thick, over 100 μm in size, and very stable under ambient conditions. They show 2D characteristics of superconducting transitions that are consistent with Berezinskii-Kosterlitz-Thouless behaviour and show strong anisotropy with magnetic field orientation; moreover, the superconductivity is also strongly dependent on the crystal thickness. Our versatile CVD process allows the fabrication of other high-quality 2D TMC crystals, such as ultrathin WC and TaC crystals, which further expand the large family of 2D materials.
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Affiliation(s)
- Chuan Xu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Libin Wang
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
| | - Zhibo Liu
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Long Chen
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jingkun Guo
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
| | - Ning Kang
- Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China
| | - Xiu-Liang Ma
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Hui-Ming Cheng
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Wencai Ren
- Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
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39
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Baiutti F, Logvenov G, Gregori G, Cristiani G, Wang Y, Sigle W, van Aken PA, Maier J. High-temperature superconductivity in space-charge regions of lanthanum cuprate induced by two-dimensional doping. Nat Commun 2015; 6:8586. [PMID: 26481902 PMCID: PMC4634214 DOI: 10.1038/ncomms9586] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 09/09/2015] [Indexed: 11/18/2022] Open
Abstract
The exploitation of interface effects turned out to be a powerful tool for generating exciting material properties. Such properties include magnetism, electronic and ionic transport and even superconductivity. Here, instead of using conventional homogeneous doping to enhance the hole concentration in lanthanum cuprate and achieve superconductivity, we replace single LaO planes with SrO dopant planes using atomic-layer-by-layer molecular beam epitaxy (two-dimensional doping). Electron spectroscopy and microscopy, conductivity measurements and zinc tomography reveal such negatively charged interfaces to induce layer-dependent superconductivity (Tc up to 35 K) in the space-charge zone at the side of the planes facing the substrate, where the strontium (Sr) profile is abrupt. Owing to the growth conditions, the other side exhibits instead a Sr redistribution resulting in superconductivity due to conventional doping. The present study represents a successful example of two-dimensional doping of superconducting oxide systems and demonstrates its power in this field. Introduction of higher-dimensional structure elements into solids is used to generate unusual materials properties. Here, the authors report how replacing LaO planes with SrO dopants yields space-charge induced superconductivity, showing the potential of two-dimensional doping in this field.
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Affiliation(s)
- F Baiutti
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - G Logvenov
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - G Gregori
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - G Cristiani
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
| | - Y Wang
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart 70569, Germany
| | - W Sigle
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart 70569, Germany
| | - P A van Aken
- Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart 70569, Germany
| | - J Maier
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart 70569, Germany
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40
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Lee H, Cheong S, Kim BG. Hybrid functional band gap calculation of SnO6 containing perovskites and their derived structures. J SOLID STATE CHEM 2015. [DOI: 10.1016/j.jssc.2015.04.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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41
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Ge JF, Liu ZL, Liu C, Gao CL, Qian D, Xue QK, Liu Y, Jia JF. Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3. NATURE MATERIALS 2015; 14:285-9. [PMID: 25419814 DOI: 10.1038/nmat4153] [Citation(s) in RCA: 280] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 10/30/2014] [Indexed: 05/05/2023]
Abstract
Recent experiments on FeSe films grown on SrTiO3 (STO) suggest that interface effects can be used as a means to reach superconducting critical temperatures (Tc) of up to 80 K (ref. ). This is nearly ten times the Tc of bulk FeSe and higher than the record value of 56 K for known bulk Fe-based superconductors. Together with recent studies of superconductivity at oxide heterostructure interfaces, these results rekindle the long-standing idea that electron pairing at interfaces between two different materials can be tailored to achieve high-temperature superconductivity. Subsequent angle-resolved photoemission spectroscopy measurements of the FeSe/STO system revealed an electronic structure distinct from bulk FeSe (refs , ), with an energy gap vanishing at around 65 K. However, ex situ electrical transport measurements have so far detected zero resistance-the key experimental signature of superconductivity-only below 30 K. Here, we report the observation of superconductivity with Tc above 100 K in the FeSe/STO system by means of in situ four-point probe electrical transport measurements. This finding confirms FeSe/STO as an ideal material for studying high-Tc superconductivity.
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Affiliation(s)
- Jian-Feng Ge
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China
| | - Zhi-Long Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China
| | - Canhua Liu
- 1] Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Chun-Lei Gao
- 1] Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Dong Qian
- 1] Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Qi-Kun Xue
- Department of Physics, Tsinghua University, Beijing 100084, China
| | - Ying Liu
- 1] Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China [3] Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Jin-Feng Jia
- 1] Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road Shanghai 200240, China [2] Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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Herranz G, Singh G, Bergeal N, Jouan A, Lesueur J, Gázquez J, Varela M, Scigaj M, Dix N, Sánchez F, Fontcuberta J. Engineering two-dimensional superconductivity and Rashba spin-orbit coupling in LaAlO₃/SrTiO₃ quantum wells by selective orbital occupancy. Nat Commun 2015; 6:6028. [PMID: 25583368 PMCID: PMC4308716 DOI: 10.1038/ncomms7028] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/03/2014] [Indexed: 11/09/2022] Open
Abstract
The discovery of two-dimensional electron gases (2DEGs) at oxide interfaces-involving electrons in narrow d-bands-has broken new ground, enabling the access to correlated states that are unreachable in conventional semiconductors based on s- and p- electrons. There is a growing consensus that emerging properties at these novel quantum wells-such as 2D superconductivity and magnetism-are intimately connected to specific orbital symmetries in the 2DEG sub-band structure. Here we show that crystal orientation allows selective orbital occupancy, disclosing unprecedented ways to tailor the 2DEG properties. By carrying out electrostatic gating experiments in LaAlO3/SrTiO3 wells of different crystal orientations, we show that the spatial extension and anisotropy of the 2D superconductivity and the Rashba spin-orbit field can be largely modulated by controlling the 2DEG sub-band filling. Such an orientational tuning expands the possibilities for electronic engineering of 2DEGs at LaAlO3/SrTiO3 interfaces.
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Affiliation(s)
- Gervasi Herranz
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Gyanendra Singh
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Nicolas Bergeal
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Alexis Jouan
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Jérôme Lesueur
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Jaume Gázquez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - María Varela
- 1] Materials Science &Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] GFMC, Department de Fisica Aplicada III &Instituto Pluridisciplinar, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Mateusz Scigaj
- 1] Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain [2] Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
| | - Nico Dix
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Florencio Sánchez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Josep Fontcuberta
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
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43
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Asmara TC, Santoso I, Rusydi A. Self-consistent iteration procedure in analyzing reflectivity and spectroscopic ellipsometry data of multilayered materials and their interfaces. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2014; 85:123116. [PMID: 25554281 DOI: 10.1063/1.4897487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
For multilayered materials, reflectivity depends on the complex dielectric function of all the constituent layers, and a detailed analysis is required to separate them. Furthermore, for some cases, new quantum states can occur at the interface which may change the optical properties of the material. In this paper, we discuss various aspects of such analysis, and present a self-consistent iteration procedure, a versatile method to extract and separate the complex dielectric function of each individual layer of a multilayered system. As a case study, we apply this method to LaAlO3/SrTiO3 heterostructure in which we are able to separate the effects of the interface from the LaAlO3 film and the SrTiO3 substrate. Our method can be applied to other complex multilayered systems with various numbers of layers.
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Affiliation(s)
- T C Asmara
- NUSNNI-NanoCore, Singapore Synchrotron Light Source, and Department of Physics, National University of Singapore, Singapore 117576
| | - I Santoso
- NUSNNI-NanoCore, Singapore Synchrotron Light Source, and Department of Physics, National University of Singapore, Singapore 117576
| | - A Rusydi
- NUSNNI-NanoCore, Singapore Synchrotron Light Source, and Department of Physics, National University of Singapore, Singapore 117576
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44
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Macke S, Radi A, Hamann-Borrero JE, Verna A, Bluschke M, Brück S, Goering E, Sutarto R, He F, Cristiani G, Wu M, Benckiser E, Habermeier HU, Logvenov G, Gauquelin N, Botton GA, Kajdos AP, Stemmer S, Sawatzky GA, Haverkort MW, Keimer B, Hinkov V. Element specific monolayer depth profiling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:6554-6559. [PMID: 25103570 DOI: 10.1002/adma.201402028] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/25/2014] [Indexed: 06/03/2023]
Abstract
The electronic phase behavior and functionality of interfaces and surfaces in complex materials are strongly correlated to chemical composition profiles, stoichiometry and intermixing. Here a novel analysis scheme for resonant X-ray reflectivity maps is introduced to determine such profiles, which is element specific and non-destructive, and which exhibits atomic-layer resolution and a probing depth of hundreds of nanometers.
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Affiliation(s)
- Sebastian Macke
- Quantum Matter Institute and Department of Physics and Astronomy, University of British Columbia, 2355 East Mall, Vancouver, V6T 1Z4, Canada; Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569, Stuttgart, Germany
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45
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Cooper VR, Seo SSA, Lee S, Kim JS, Choi WS, Okamoto S, Lee HN. Transparent conducting oxides: a δ-doped superlattice approach. Sci Rep 2014; 4:6021. [PMID: 25109668 PMCID: PMC4127498 DOI: 10.1038/srep06021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 07/25/2014] [Indexed: 11/30/2022] Open
Abstract
Metallic states appearing at interfaces between dissimilar insulating oxides exhibit intriguing phenomena such as superconductivity and magnetism. Despite tremendous progress in understanding their origins, very little is known about how to control the conduction pathways and the distribution of charge carriers. Using optical spectroscopic measurements and density-functional theory (DFT) simulations, we examine the effect of SrTiO3 (STO) spacer layer thickness on the optical transparency and carrier distribution in La δ-doped STO superlattices. We experimentally observe that these metallic superlattices remain highly transparent to visible light; a direct consequence of the appropriately large gap between the O 2p and Ti 3d states. In superlattices with relatively thin STO layers, we predict that three-dimensional conduction would occur due to appreciable overlap of quantum mechanical wavefunctions between neighboring δ-doped layers. These results highlight the potential for using oxide heterostructures in optoelectronic devices by providing a unique route for creating novel transparent conducting oxides.
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Affiliation(s)
- Valentino R Cooper
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sung S Ambrose Seo
- 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506, USA
| | - Suyoun Lee
- 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Electronic Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Jun Sung Kim
- Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Woo Seok Choi
- 1] Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 440-746, Korea
| | - Satoshi Okamoto
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Ho Nyung Lee
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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46
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Nie YF, Zhu Y, Lee CH, Kourkoutis LF, Mundy JA, Junquera J, Ghosez P, Baek DJ, Sung S, Xi XX, Shen KM, Muller DA, Schlom DG. Atomically precise interfaces from non-stoichiometric deposition. Nat Commun 2014; 5:4530. [DOI: 10.1038/ncomms5530] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 06/27/2014] [Indexed: 11/09/2022] Open
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47
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King PDC, McKeown Walker S, Tamai A, de la Torre A, Eknapakul T, Buaphet P, Mo SK, Meevasana W, Bahramy MS, Baumberger F. Quasiparticle dynamics and spin–orbital texture of the SrTiO3 two-dimensional electron gas. Nat Commun 2014; 5:3414. [DOI: 10.1038/ncomms4414] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 02/07/2014] [Indexed: 11/10/2022] Open
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48
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Wu J, Pelleg O, Logvenov G, Bollinger AT, Sun YJ, Boebinger GS, Vanević M, Radović Z, Božović I. Anomalous independence of interface superconductivity from carrier density. NATURE MATERIALS 2013; 12:877-881. [PMID: 23913171 DOI: 10.1038/nmat3719] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/24/2013] [Indexed: 06/02/2023]
Abstract
The recent discovery of superconductivity at the interface of two non-superconducting materials has received much attention. In cuprate bilayers, the critical temperature (Tc) can be significantly enhanced compared with single-phase samples. Several explanations have been proposed, invoking Sr interdiffusion, accumulation and depletion of mobile charge carriers, elongation of the copper-to-apical-oxygen bond length, or a beneficial crosstalk between a material with a high pairing energy and another with a large phase stiffness. From each of these models, one would predict Tc to depend strongly on the carrier density in the constituent materials. Here, we study combinatorial libraries of La(2-x)Sr(x)CuO4-La2CuO4 bilayer samples--an unprecedentedly large set of more than 800 different compositions. The doping level x spans a wide range, 0.15 < x < 0.47, and the measured Hall coefficient varies by one order of magnitude. Nevertheless, across the entire sample set, Tc stays essentially constant at about 40 K. We infer that doping up to the optimum level does not shift the chemical potential, unlike in ordinary Fermi liquids. This result poses a new challenge to theory--cuprate superconductors have not run out of surprises.
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Affiliation(s)
- J Wu
- 1] Brookhaven National Laboratory, Upton, New York 11973-5000, USA [2] National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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49
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Jeong JS, Ambwani P, Jalan B, Leighton C, Mkhoyan KA. Observation of electrically-inactive interstitials in Nb-doped SrTiO3. ACS NANO 2013; 7:4487-4494. [PMID: 23621788 DOI: 10.1021/nn401101y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Despite rapid recent progress, controlled dopant incorporation and attainment of high mobility in thin films of the prototypical complex oxide semiconductor SrTiO3 remain problematic. Here, analytical scanning transmission electron microscopy is used to study the local atomic and electronic structure of Nb-doped SrTiO3 both in ideally substitutionally doped bulk single crystals and epitaxial thin films. The films are deposited under conditions that would yield highly stoichiometric undoped SrTiO3, but are nevertheless insulating. The Nb incorporation in such films was found to be highly inhomogeneous on nanoscopic length-scales, with large quantities of what we deduce to be interstitial Nb. Electron energy loss spectroscopy reveals changes in the electronic density of states in Nb-doped SrTiO3 films compared to undoped SrTiO3, but without the clear shift in the Fermi edge seen in bulk single crystal Nb-doped SrTiO3. Analysis of atomic-resolution annular dark-field images allows us to conclude that the interstitial Nb is in the Nb(0) state, confirming that it is electrically inactive. We argue that this approach should enable future work establishing the vitally needed relationships between synthesis/processing conditions and electronic properties of Nb-doped SrTiO3 thin films.
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Affiliation(s)
- Jong Seok Jeong
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
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50
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Irvin P, Veazey JP, Cheng G, Lu S, Bark CW, Ryu S, Eom CB, Levy J. Anomalous high mobility in LaAlO3/SrTiO3 nanowires. NANO LETTERS 2013; 13:364-368. [PMID: 23305110 DOI: 10.1021/nl3033729] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Nanoscale control of the metal-insulator transition at the interface between LaAlO(3) and SrTiO(3) provides a pathway for reconfigurable, oxide-based nanoelectronics. Four-terminal transport measurements of LaAlO(3)/SrTiO(3) nanowires at room temperature (T = 300 K) reveal an equivalent 2D Hall mobility greatly surpassing that of bulk SrTiO(3) and approaching that of n-type Si nanowires of comparable dimensions. This large enhancement of mobility is relevant for room-temperature device applications.
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Affiliation(s)
- Patrick Irvin
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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