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Nethwewala A, Lee H, Li J, Briggeman M, Pai YY, Eom K, Eom CB, Irvin P, Levy J. Electron pairing and nematicity in LaAlO 3/SrTiO 3 nanostructures. Nat Commun 2023; 14:7657. [PMID: 37996464 PMCID: PMC10667274 DOI: 10.1038/s41467-023-43539-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 11/13/2023] [Indexed: 11/25/2023] Open
Abstract
Strongly correlated electronic systems exhibit a wealth of unconventional behavior stemming from strong electron-electron interactions. The LaAlO3/SrTiO3 (LAO/STO) heterostructure supports rich and varied low-temperature transport characteristics including low-density superconductivity, and electron pairing without superconductivity for which the microscopic origins is still not understood. LAO/STO also exhibits inexplicable signatures of electronic nematicity via nonlinear and anomalous Hall effects. Nanoscale control over the conductivity of the LAO/STO interface enables mesoscopic experiments that can probe these effects and address their microscopic origins. Here we report a direct correlation between electron pairing without superconductivity, anomalous Hall effect and electronic nematicity in quasi-1D ballistic nanoscale LAO/STO Hall crosses. The characteristic magnetic field at which the Hall coefficient changes directly coincides with the depairing of non-superconducting pairs showing a strong correlation between the two distinct phenomena. Angle-dependent Hall measurements further reveal an onset of electronic nematicity that again coincides with the electron pairing transition, unveiling a rotational symmetry breaking due to the transition from paired to unpaired phases at the interface. The results presented here highlights the influence of preformed electron pairs on the transport properties of LAO/STO and provide evidence of the elusive pairing "glue" that gives rise to electron pairing in SrTiO3-based systems.
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Affiliation(s)
- Aditi Nethwewala
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jianan Li
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA
- Pittsburgh Quantum Institute, Pittsburgh, PA, 15260, USA
| | - Megan Briggeman
- 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
| | - Kitae Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - 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.
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA, 15260, USA.
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2
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Mallik S, Ménard GC, Saïz G, Gilmutdinov I, Vignolles D, Proust C, Gloter A, Bergeal N, Gabay M, Bibes M. From Low-Field Sondheimer Oscillations to High-Field Very Large and Linear Magnetoresistance in a SrTiO 3-Based Two-Dimensional Electron Gas. NANO LETTERS 2022; 22:65-72. [PMID: 34914397 DOI: 10.1021/acs.nanolett.1c03198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantum materials harbor a cornucopia of exotic transport phenomena challenging our understanding of condensed matter. Among these, a giant, nonsaturating linear magnetoresistance (MR) has been reported in various systems, from Weyl semimetals to topological insulators. Its origin is often ascribed to unusual band structure effects, but it may also be caused by extrinsic sample disorder. Here, we report a very large linear MR in a SrTiO3 two-dimensional electron gas and, by combining transport measurements with electron spectromicroscopy, show that it is caused by nanoscale inhomogeneities that are self-organized during sample growth. Our data also reveal semiclassical Sondheimer oscillations arising from interferences between helicoidal electron trajectories, from which we determine the 2DEG thickness. Our results bring insight into the origin of linear MR in quantum materials, expand the range of functionalities of oxide 2DEGs, and suggest exciting routes to explore the interaction of linear MR with features like Rashba spin-orbit coupling.
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Affiliation(s)
- Srijani Mallik
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France
| | - Gerbold C Ménard
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 75005 Paris, France
| | - Guilhem Saïz
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 75005 Paris, France
| | - Ildar Gilmutdinov
- LNCMI-EMFL, CNRS, Université Grenoble Alpes, INSA-T, UPS, 31400 Toulouse, France
| | - David Vignolles
- LNCMI-EMFL, CNRS, Université Grenoble Alpes, INSA-T, UPS, 31400 Toulouse, France
| | - Cyril Proust
- LNCMI-EMFL, CNRS, Université Grenoble Alpes, INSA-T, UPS, 31400 Toulouse, France
| | - Alexandre Gloter
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, 91405 Orsay, France
| | - Nicolas Bergeal
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL University, CNRS, Sorbonne Université, 75005 Paris, France
| | - Marc Gabay
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS UMR 8502, 91405 Orsay, France
| | - Manuel Bibes
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 1 Avenue Augustin Fresnel, 91767 Palaiseau, France
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3
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Chen X, Zhang J, Liu B, Hu F, Shen B, Sun J. Two-dimensional conducting states in infinite-layer oxide/perovskite oxide hetero-structures. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 34:035003. [PMID: 34663765 DOI: 10.1088/1361-648x/ac30b6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
Heterointerfaces sandwiched by oxides of dissimilar crystal structures will show strong interface reconstruction, leading to distinct interfacial effect arising from unusual physics. Here, we present a theoretical investigation on the interfaces between infinite-layer oxide and perovskite oxide (SrCuO2/SrTiO3and SrCuO2/KTaO3). Surprisingly, we found well-defined two-dimensional electron gas (2DEG), stemming from atomic reconstruction and polar discontinuity at interface. Moreover, the 2DEG resides in both the TiO2and CuO2interfacial layers, unlike LaAlO3/SrTiO3for which 2DEG exists only in the TiO2interfacial layer. More than that, no metal-to-insulator transition is observed as the SrCuO2layer thickness decreases to one unit cell, i.e., the metallicity of the new interface is robust. Further investigations show more unique features of the 2DEG. Due to the absence of apical oxygen at the SrCuO2/SrTiO3(KTaO3) interface, the conducting states in the interface TiO2(TaO2) layer follows thedxy<d3z2-r2<dxz/yzorbital order rather than thedxy<dxz/yzorbital order of paradigm LaAlO3/SrTiO3(KTaO3), exhibiting enhanced interfacial conduction. This work suggests the great potential of heterointerfaces composed of non-isostructural oxides for fundamental research.
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Affiliation(s)
- Xiaobing Chen
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jine Zhang
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, People's Republic of China
| | - Banggui Liu
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fengxia Hu
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics & Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
- Spintronics Institute, University of Jinan, Jinan, Shandong 250022, People's Republic of China
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4
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Leermakers I, Rubi K, Yang M, Kerdi B, Goiran M, Escoffier W, Rana AS, Smink AEM, Brinkman A, Hilgenkamp H, Maan JC, Zeitler U. Quantum oscillations in an optically-illuminated two-dimensional electron system at the LaAlO 3/SrTiO 3interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465002. [PMID: 34433152 DOI: 10.1088/1361-648x/ac211a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
We have investigated the illumination effect on the magnetotransport properties of a two-dimensional electron system at the LaAlO3/SrTiO3interface. The illumination significantly reduces the zero-field sheet resistance, eliminates the Kondo effect at low-temperature, and switches the negative magnetoresistance into the positive one. A large increase in the density of high-mobility carriers after illumination leads to quantum oscillations in the magnetoresistance originating from the Landau quantization. The carrier density (∼2 × 1012 cm-2) and effective mass (∼1.7me) estimated from the oscillations suggest that the high-mobility electrons occupy thedxz/yzsubbands of Ti:t2gorbital extending deep within the conducting sheet of SrTiO3. Our results demonstrate that the illumination which induces additional carriers at the interface can pave the way to control the Kondo-like scattering and study the quantum transport in the complex oxide heterostructures.
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Affiliation(s)
- I Leermakers
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - K Rubi
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - M Yang
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - B Kerdi
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - M Goiran
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - W Escoffier
- Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), Université de Toulouse, CNRS, INSA, UPS, 143 Avenue de Rangueil, 31400 Toulouse, France
| | - A S Rana
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - A E M Smink
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - A Brinkman
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - H Hilgenkamp
- MESA + Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - J C Maan
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - U Zeitler
- High Field Magnet Laboratory (HFML-EMFL) and Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
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5
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Rose MA, Šmíd B, Vorokhta M, Slipukhina I, Andrä M, Bluhm H, Duchoň T, Ležaić M, Chambers SA, Dittmann R, Mueller DN, Gunkel F. Identifying Ionic and Electronic Charge Transfer at Oxide Heterointerfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2004132. [PMID: 33263190 DOI: 10.1002/adma.202004132] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/31/2020] [Indexed: 06/12/2023]
Abstract
The ability to tailor oxide heterointerfaces has led to novel properties in low-dimensional oxide systems. A fundamental understanding of these properties is based on the concept of electronic charge transfer. However, the electronic properties of oxide heterointerfaces crucially depend on their ionic constitution and defect structure: ionic charges contribute to charge transfer and screening at oxide interfaces, triggering a thermodynamic balance of ionic and electronic structures. Quantitative understanding of the electronic and ionic roles regarding charge-transfer phenomena poses a central challenge. Here, the electronic and ionic structure is simultaneously investigated at the prototypical charge-transfer heterointerface, LaAlO3 /SrTiO3 . Applying in situ photoemission spectroscopy under oxygen ambient, ionic and electronic charge transfer is deconvoluted in response to the oxygen atmosphere at elevated temperatures. In this way, both the rich and variable chemistry of complex oxides and the associated electronic properties are equally embraced. The interfacial electron gas is depleted through an ionic rearrangement in the strontium cation sublattice when oxygen is applied, resulting in an inverse and reversible balance between cation vacancies and electrons, while the mobility of ionic species is found to be considerably enhanced as compared to the bulk. Triggered by these ionic phenomena, the electronic transport and magnetic signature of the heterointerface are significantly altered.
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Affiliation(s)
- Marc-André Rose
- Institute for Electronic Materials (IWE 2), and Juelich-Aachen Research Alliance for Fundamentals on Future Information Technology (JARA-FIT), RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - Břetislav Šmíd
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, 180 00, Czech Republic
| | - Mykhailo Vorokhta
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Prague, 180 00, Czech Republic
| | - Ivetta Slipukhina
- Peter Grünberg Institute 1 and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA-FIT, 52425, Jülich, Germany
| | - Michael Andrä
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - Hendrik Bluhm
- Chemical Sciences Division, Lawrence Berkeley National Lab., Berkeley, CA, 94720, USA
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, 14195, Berlin, Germany
| | - Tomáš Duchoň
- Peter Grünberg Institute 6, and JARA-FIT, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Marjana Ležaić
- Peter Grünberg Institute 1 and Institute for Advanced Simulation, Forschungszentrum Jülich GmbH and JARA-FIT, 52425, Jülich, Germany
| | - Scott A Chambers
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Regina Dittmann
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
| | - David N Mueller
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
- Peter Grünberg Institute 6, and JARA-FIT, Forschungszentrum Jülich GmbH, 52425, Jülich, Germany
| | - Felix Gunkel
- Institute for Electronic Materials (IWE 2), and Juelich-Aachen Research Alliance for Fundamentals on Future Information Technology (JARA-FIT), RWTH Aachen University, 52074, Aachen, Germany
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, and JARA-FIT, 52425, Jülich, Germany
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6
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Zhang J, Zhang H, Zhang H, Ma Y, Chen X, Meng F, Qi S, Chen Y, Hu F, Zhang Q, Liu B, Shen B, Zhao W, Han W, Sun J. Long-Range Magnetic Order in Oxide Quantum Wells Hosting Two-Dimensional Electron Gases. ACS APPLIED MATERIALS & INTERFACES 2020; 12:28775-28782. [PMID: 32459951 DOI: 10.1021/acsami.0c05332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To incorporate spintronics functionalities into two-dimensional devices, it is strongly desired to get two-dimensional electron gases (2DEGs) with high spin polarization. Unfortunately, the magnetic characteristics of the typical 2DEG at the LaAlO3/SrTiO3 interface are very weak due to the nonmagnetic character of SrTiO3 and LaAlO3. While most of the previous works focused on perovskite oxides, here, we extended the exploration for magnetic 2DEG beyond the scope of perovskite combinations, composing 2DEG with SrTiO3 and NaCl-structured EuO that owns a large saturation magnetization and a fairly high Curie temperature. We obtained the 2DEGs that show long-range magnetic order and thus unusual behaviors marked by isotropic butterfly shaped magnetoresistance and remarkable anomalous Hall effect. We found evidence for the presence of more conductive domain walls than elsewhere in the oxide layer where the 2DEG resides. More than that, a relation between interfacial magnetism and carrier density is established. On this basis, the intermediate magnetic states between short-range and long-range ordered states can be achieved. The present work provides guidance for the design of high-performance magnetic 2DEGs.
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Affiliation(s)
- Jine Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Hui Zhang
- Fert Beijing Institute, School of Microelectronics, Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang University, Beijing 100191, People's Republic of China
| | - Hongrui Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yang Ma
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Xiaobing Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Fanqi Meng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Shaojin Qi
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yuansha Chen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Fengxia Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Qinghua Zhang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - Banggui Liu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Baogen Shen
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
| | - Weisheng Zhao
- Fert Beijing Institute, School of Microelectronics, Beijing Advanced Innovation Center for Big Data and Brain Computing, Beihang University, Beijing 100191, People's Republic of China
| | - Wei Han
- International Centre for Quantum Materials, School of Physics, Peking University, Beijing 100871, People's Republic of China
- Collaborative Innovation Centre of Quantum Matter, Beijing 100871, People's Republic of China
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, People's Republic of China
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7
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Wang Y, Qian P, Liu Y, Zhang FM, Cai HL, Wu XS, Zhang GP. Modulating the electronic and optical properties for SrTiO 3/LaAlO 3 bilayers treated as the 2D materials by biaxial strains. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:215701. [PMID: 31995526 DOI: 10.1088/1361-648x/ab70c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The emerging two-dimensional (2D) materials such as graphene have opened the door to industrial applications. Here, we consider the oxide perovskite monolayer of SrTiO3 (STO), LaAlO3 (LAO) and their heterostructures as the 2D transitional metal system. Results show that a band-gap transition from indirect to direct occurs when the separated monolayer STO (indirect band gap of 3.210 eV), and LAO (indirect band gap of 4.024 eV), form the heterostructures (direct band gap of 2.976 eV). The obtained bandgap for the stable bilayers may effectively be modulated by biaxial strains from -12% to 8%. With 12% compressive biaxial strain, the band gap reduces to be 0.23 eV. The optical properties for the stable bilayers are also tuned by the biaxial strain. When the strain increases from compressive strain to tensile strain, the strongest peak of the imaginary part of dielectric function red shifts to lower energy. In comparing with the monolayer STO and LAO, the elastic property enhances obviously for the stable heterostructure, suggesting the heterostructure can be more stable freestanding or may be applied in device fabrications.
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Affiliation(s)
- Yan Wang
- Collaborative Innovation Center of Advanced Microstructures, Laboratory of Solid State Microstructures & School of Physics, Nanjing University, Nanjing 210093, People's Republic of China
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8
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Choe D, Jin MJ, Kim SI, Choi HJ, Jo J, Oh I, Park J, Jin H, Koo HC, Min BC, Hong S, Lee HW, Baek SH, Yoo JW. Gate-tunable giant nonreciprocal charge transport in noncentrosymmetric oxide interfaces. Nat Commun 2019; 10:4510. [PMID: 31586096 PMCID: PMC6778138 DOI: 10.1038/s41467-019-12466-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 09/06/2019] [Indexed: 11/09/2022] Open
Abstract
A polar conductor, where inversion symmetry is broken, may exhibit directional propagation of itinerant electrons, i.e., the rightward and leftward currents differ from each other, when time-reversal symmetry is also broken. This potential rectification effect was shown to be very weak due to the fact that the kinetic energy is much higher than the energies associated with symmetry breaking, producing weak perturbations. Here we demonstrate the appearance of giant nonreciprocal charge transport in the conductive oxide interface, LaAlO3/SrTiO3, where the electrons are confined to two-dimensions with low Fermi energy. In addition, the Rashba spin-orbit interaction correlated with the sub-band hierarchy of this system enables a strongly tunable nonreciprocal response by applying a gate voltage. The observed behavior of directional response in LaAlO3/SrTiO3 is associated with comparable energy scales among kinetic energy, spin-orbit interaction, and magnetic field, which inspires a promising route to enhance nonreciprocal response and its functionalities in spin orbitronics.
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Affiliation(s)
- Daeseong Choe
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Mi-Jin Jin
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Shin-Ik Kim
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Hyung-Jin Choi
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Junhyeon Jo
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Inseon Oh
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Jungmin Park
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea.,Center for Scientific Instrumentation, Division of Scientific Instrumentation & Management, Korea Basic Science Institute, Daejeon, 305-806, Korea
| | - Hosub Jin
- Department of Physics, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea
| | - Hyun Cheol Koo
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Korea
| | - Byoung-Chul Min
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea.,Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul, 02792, Korea
| | - Seokmin Hong
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Korea
| | - Hyun-Woo Lee
- Department of Physics, Pohang University of Science and Technology, Pohang, 37673, Korea
| | - Seung-Hyub Baek
- Center for Electronic Materials, Korea Institute of Science and Technology, Seoul, 02792, Korea.,Division of Nano and Information Technology, KIST School, Korea University of Science and Technology, Seoul, 02792, Korea
| | - Jung-Woo Yoo
- School of Materials Science and Engineering-Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan, 44919, Korea.
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9
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Singh G, Jouan A, Herranz G, Scigaj M, Sánchez F, Benfatto L, Caprara S, Grilli M, Saiz G, Couëdo F, Feuillet-Palma C, Lesueur J, Bergeal N. Gap suppression at a Lifshitz transition in a multi-condensate superconductor. NATURE MATERIALS 2019; 18:948-954. [PMID: 31086324 DOI: 10.1038/s41563-019-0354-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
In multi-orbital materials, superconductivity can exhibit several coupled condensates. In this context, quantum confinement in two-dimensional superconducting oxide interfaces offers new degrees of freedom to engineer the band structure and selectively control the occupancy of 3d orbitals by electrostatic doping. Here, we use resonant microwave transport to extract the superfluid stiffness of the (110)-oriented LaAlO3/SrTiO3 interface in the entire phase diagram. We provide evidence of a transition from single-condensate to two-condensate superconductivity driven by continuous and reversible electrostatic doping, which we relate to the Lifshitz transition between 3d bands based on numerical simulations of the quantum well. We find that the superconducting gap is suppressed while the second band is populated, challenging Bardeen-Cooper-Schrieffer theory. We ascribe this behaviour to the existence of superconducting order parameters with opposite signs in the two condensates due to repulsive coupling. Our findings offer an innovative perspective on the possibility to tune and control multiple-orbital physics in superconducting interfaces.
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Affiliation(s)
- G Singh
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - A Jouan
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - G Herranz
- Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, Catalonia, Spain
| | - M Scigaj
- Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, Catalonia, Spain
| | - F Sánchez
- Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra, Catalonia, Spain
| | - L Benfatto
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Roma, Italy
- Dipartimento di Fisica Università di Roma 'La Sapienza', Roma, Italy
| | - S Caprara
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Roma, Italy
- Dipartimento di Fisica Università di Roma 'La Sapienza', Roma, Italy
| | - M Grilli
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Roma, Italy
- Dipartimento di Fisica Università di Roma 'La Sapienza', Roma, Italy
| | - G Saiz
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - F Couëdo
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - C Feuillet-Palma
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - J Lesueur
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France
| | - N Bergeal
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, Paris, France.
- Université Pierre and Marie Curie, Sorbonne-Université, Paris, France.
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10
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Khanna U, Rout PK, Mograbi M, Tuvia G, Leermakers I, Zeitler U, Dagan Y, Goldstein M. Symmetry and Correlation Effects on Band Structure Explain the Anomalous Transport Properties of (111) LaAlO_{3}/SrTiO_{3}. PHYSICAL REVIEW LETTERS 2019; 123:036805. [PMID: 31386445 DOI: 10.1103/physrevlett.123.036805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Indexed: 06/10/2023]
Abstract
The interface between the two insulating oxides SrTiO_{3} and LaAlO_{3} gives rise to a two-dimensional electron system with intriguing transport phenomena, including superconductivity, which are controllable by a gate. Previous measurements on the (001) interface have shown that the superconducting critical temperature, the Hall density, and the frequency of quantum oscillations, vary nonmonotonically and in a correlated fashion with the gate voltage. In this Letter we experimentally demonstrate that the (111) interface features a qualitatively distinct behavior, in which the frequency of Shubnikov-de Haas oscillations changes monotonically, while the variation of other properties is nonmonotonic albeit uncorrelated. We develop a theoretical model, incorporating the different symmetries of these interfaces as well as electronic-correlation-induced band competition. We show that the latter dominates at (001), leading to similar nonmonotonicity in all observables, while the former is more important at (111), giving rise to highly curved Fermi contours, and accounting for all its anomalous transport measurements.
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Affiliation(s)
- Udit Khanna
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
| | - P K Rout
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
| | - Michael Mograbi
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
| | - Gal Tuvia
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
| | - Inge Leermakers
- High Field Magnet Laboratory (HFML-EFML), Radboud University, 6525 ED Nijmegen, Netherlands
| | - Uli Zeitler
- High Field Magnet Laboratory (HFML-EFML), Radboud University, 6525 ED Nijmegen, Netherlands
| | - Yoram Dagan
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
| | - Moshe Goldstein
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 6997801, Israel
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11
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Huang Z, Renshaw Wang X, Rusydi A, Chen J, Yang H, Venkatesan T. Interface Engineering and Emergent Phenomena in Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1802439. [PMID: 30133012 DOI: 10.1002/adma.201802439] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 07/06/2018] [Indexed: 06/08/2023]
Abstract
Complex oxide interfaces have mesmerized the scientific community in the last decade due to the possibility of creating tunable novel multifunctionalities, which are possible owing to the strong interaction among charge, spin, orbital, and structural degrees of freedom. Artificial interfacial modifications, which include defects, formal polarization, structural symmetry breaking, and interlayer interaction, have led to novel properties in various complex oxide heterostructures. These emergent phenomena not only serve as a platform for investigating strong electronic correlations in low-dimensional systems but also provide potentials for exploring next-generation electronic devices with high functionality. Herein, some recently developed strategies in engineering functional oxide interfaces and their emergent properties are reviewed.
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Affiliation(s)
- Zhen Huang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Xiao Renshaw Wang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Andrivo Rusydi
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Jingsheng Chen
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Hyunsoo Yang
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore, 5A Engineering Drive 1, Singapore, 117411, Singapore
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12
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Majorana Fermions in One-Dimensional Structures at LaAlO3/SrTiO3 Oxide Interfaces. CONDENSED MATTER 2018. [DOI: 10.3390/condmat3040037] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We study one-dimensional structures that may be formed at the LaAlO 3 /SrTiO 3 oxide interface by suitable top gating. These structures are modeled via a single-band model with Rashba spin-orbit coupling, superconductivity and a magnetic field along the one-dimensional chain. We first discuss the conditions for the occurrence of a topological superconducting phase and the related formation of Majorana fermions at the chain endpoints, highlighting a close similarity between this model and the Kitaev model, which also reflects in a similar condition the formation of a topological phase. Solving the model in real space, we also study the spatial extension of the wave function of the Majorana fermions and how this increases with approaching the limit condition for the topological state. Using a scattering matrix formalism, we investigate the stability of the Majorana fermions in the presence of disorder and discuss the evolution of the topological phase with increasing disorder.
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13
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Persky E, Kalisky B. Scanning SQUID View of Oxide Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1706653. [PMID: 29718543 DOI: 10.1002/adma.201706653] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 02/18/2018] [Indexed: 06/08/2023]
Abstract
The emergence of states of matter in low-dimensional systems is one of the most intriguing topics in condensed matter physics. Interfaces between nonmagnetic, insulating oxides are found to give rise to surprising behaviors, such as metallic conductivity, superconductivity, and magnetism. Sensitive, noninvasive local characterization tools are essential for understanding the electronic and magnetic behavior of these systems. Here, the scanning superconducting quantum interference device (SQUID) technique for local magnetic imaging is described and its contribution to the field of oxide interfaces is reviewed.
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Affiliation(s)
- Eylon Persky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, 5290002,, Israel
| | - Beena Kalisky
- Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, 5290002,, Israel
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14
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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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15
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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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16
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Singh G, Jouan A, Benfatto L, Couëdo F, Kumar P, Dogra A, Budhani RC, Caprara S, Grilli M, Lesne E, Barthélémy A, Bibes M, Feuillet-Palma C, Lesueur J, Bergeal N. Competition between electron pairing and phase coherence in superconducting interfaces. Nat Commun 2018; 9:407. [PMID: 29379023 PMCID: PMC5789063 DOI: 10.1038/s41467-018-02907-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 01/08/2018] [Indexed: 11/29/2022] Open
Abstract
In LaAlO3/SrTiO3 heterostructures, a gate tunable superconducting electron gas is confined in a quantum well at the interface between two insulating oxides. Remarkably, the gas coexists with both magnetism and strong Rashba spin-orbit coupling. However, both the origin of superconductivity and the nature of the transition to the normal state over the whole doping range remain elusive. Here we use resonant microwave transport to extract the superfluid stiffness and the superconducting gap energy of the LaAlO3/SrTiO3 interface as a function of carrier density. We show that the superconducting phase diagram of this system is controlled by the competition between electron pairing and phase coherence. The analysis of the superfluid density reveals that only a very small fraction of the electrons condenses into the superconducting state. We propose that this corresponds to the weak filling of high-energy dxz/dyz bands in the quantum well, more apt to host superconductivity.
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Affiliation(s)
- G Singh
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France
| | - A Jouan
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France
| | - L Benfatto
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy.
- Dipartimento di Fisica Università di Roma "La Sapienza", Piazzale A. Moro 5, 00185, Roma, Italy.
| | - F Couëdo
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France
| | - P Kumar
- National Physical Laboratory, Council of Scientific and Industrial Research (CSIR), Dr. K.S. Krishnan Marg, New Delhi, 110012, India
| | - A Dogra
- National Physical Laboratory, Council of Scientific and Industrial Research (CSIR), Dr. K.S. Krishnan Marg, New Delhi, 110012, India
| | - R C Budhani
- Condensed Matter Low Dimensional Systems Laboratory, Department of Physics, Indian Institute of Technology, Kanpur, 208016, India
| | - S Caprara
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy
- Dipartimento di Fisica Università di Roma "La Sapienza", Piazzale A. Moro 5, 00185, Roma, Italy
| | - M Grilli
- Institute for Complex Systems (ISC-CNR), UOS Sapienza, Piazzale A. Moro 5, 00185, Roma, Italy
- Dipartimento di Fisica Università di Roma "La Sapienza", Piazzale A. Moro 5, 00185, Roma, Italy
| | - E Lesne
- Unité Mixte de Physique CNRS-Thales, 1 Av. A. Fresnel, 91767, Palaiseau, France
| | - A Barthélémy
- Unité Mixte de Physique CNRS-Thales, 1 Av. A. Fresnel, 91767, Palaiseau, France
| | - M Bibes
- Unité Mixte de Physique CNRS-Thales, 1 Av. A. Fresnel, 91767, Palaiseau, France
| | - C Feuillet-Palma
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France
| | - J Lesueur
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France
| | - N Bergeal
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, PSL Research University, CNRS, 10 Rue Vauquelin, 75005, Paris, France.
- Université Pierre and Marie Curie, Sorbonne-Universités, 75005, Paris, France.
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17
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Bano A, Gaur NK. Interfacial Coupling Effect on Electron Transport in MoS 2/SrTiO 3 Heterostructure: An Ab-initio Study. Sci Rep 2018; 8:714. [PMID: 29335594 PMCID: PMC5768749 DOI: 10.1038/s41598-017-18984-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/15/2017] [Indexed: 11/24/2022] Open
Abstract
A variety of theoretical and experimental works have reported several potential applications of MoS2 monolayer based heterostructures (HSs) such as light emitting diodes, photodetectors and field effect transistors etc. In the present work, we have theoretically performed as a model case study, MoS2 monolayer deposited over insulating SrTiO3 (001) to study the band alignment at TiO2 termination. The interfacial characteristics are found to be highly dependent on the interface termination. With an insulating oxide material, a significant band gap (0.85eV) is found in MoS2/TiO2 interface heterostructure (HS). A unique electronic band profile with an indirect band gap (0.67eV) is observed in MoS2 monolayer when confined in a cubic environment of SrTiO3 (STO). Adsorption analysis showed the chemisorption of MoS2 on the surface of STO substrate with TiO2 termination which is justified by the charge density calculations that shows the existence of covalent bonding at the interface. The fabrication of HS of such materials paves the path for developing the unprecedented 2D materials with exciting properties such as semiconducting devices, thermoelectric and optoelectronic applications.
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Affiliation(s)
- Amreen Bano
- Department of Physics, Barkatullah University, Bhopal, 462026, India.
| | - N K Gaur
- Department of Physics, Barkatullah University, Bhopal, 462026, India
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18
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Rout PK, Maniv E, Dagan Y. Link between the Superconducting Dome and Spin-Orbit Interaction in the (111) LaAlO_{3}/SrTiO_{3} Interface. PHYSICAL REVIEW LETTERS 2017; 119:237002. [PMID: 29286685 DOI: 10.1103/physrevlett.119.237002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Indexed: 06/07/2023]
Abstract
We measure the gate voltage (V_{g}) dependence of the superconducting properties and the spin-orbit interaction in the (111)-oriented LaAlO_{3}/SrTiO_{3} interface. Superconductivity is observed in a dome-shaped region in the carrier density-temperature phase diagram with the maxima of superconducting transition temperature T_{c} and the upper critical fields lying at the same V_{g}. The spin-orbit interaction determined from the superconducting parameters and confirmed by weak-antilocalization measurements follows the same gate voltage dependence as T_{c}. The correlation between the superconductivity and spin-orbit interaction as well as the enhancement of the parallel upper critical field, well beyond the Chandrasekhar-Clogston limit, suggest that superconductivity and the spin-orbit interaction are linked in a nontrivial fashion. We propose possible scenarios to explain this unconventional behavior.
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Affiliation(s)
- P K Rout
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978, Israel
| | - E Maniv
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978, Israel
| | - Y Dagan
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv 69978, Israel
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19
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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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20
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Maniv E, Dagan Y, Goldstein M. Correlation-Induced Band Competition in SrTiO3/LaAlO3. ACTA ACUST UNITED AC 2017. [DOI: 10.1557/adv.2017.92] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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21
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Chen Z, Yuan H, Xie Y, Lu D, Inoue H, Hikita Y, Bell C, Hwang HY. Dual-Gate Modulation of Carrier Density and Disorder in an Oxide Two-Dimensional Electron System. NANO LETTERS 2016; 16:6130-6136. [PMID: 27605459 DOI: 10.1021/acs.nanolett.6b02348] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Carrier density and disorder are two crucial parameters that control the properties of correlated two-dimensional electron systems. In order to disentangle their individual contributions to quantum phenomena, independent tuning of these two parameters is required. Here, by utilizing a hybrid liquid/solid electric dual-gate geometry acting on the conducting LaAlO3/SrTiO3 heterointerface, we obtain an additional degree of freedom to strongly modify the electron confinement profile and thus the strength of interfacial scattering, independent from the carrier density. A dual-gate controlled nonlinear Hall effect is a direct manifestation of this profile, which can be quantitatively understood by a Poisson-Schrödinger sub-band model. In particular, the large nonlinear dielectric response of SrTiO3 enables a very wide range of tunable density and disorder, far beyond that for conventional semiconductors. Our study provides a broad framework for understanding various reported phenomena at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Zhuoyu Chen
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Hongtao Yuan
- 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
| | - Yanwu Xie
- 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
| | - Hisashi Inoue
- Geballe Laboratory for Advanced Materials, Stanford University , Stanford, California 94305, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Christopher Bell
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
- H.H. Wills Physics Laboratory, University of Bristol , Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - 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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22
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Trier F, Prawiroatmodjo GEDK, Zhong Z, Christensen DV, von Soosten M, Bhowmik A, Lastra JMG, Chen Y, Jespersen TS, Pryds N. Quantization of Hall Resistance at the Metallic Interface between an Oxide Insulator and SrTiO_{3}. PHYSICAL REVIEW LETTERS 2016; 117:096804. [PMID: 27610874 DOI: 10.1103/physrevlett.117.096804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Indexed: 06/06/2023]
Abstract
The two-dimensional metal forming at the interface between an oxide insulator and SrTiO_{3} provides new opportunities for oxide electronics. However, the quantum Hall effect, one of the most fascinating effects of electrons confined in two dimensions, remains underexplored at these complex oxide heterointerfaces. Here, we report the experimental observation of quantized Hall resistance in a SrTiO_{3} heterointerface based on the modulation-doped amorphous-LaAlO_{3}/SrTiO_{3} heterostructure, which exhibits both high electron mobility exceeding 10,000 cm^{2}/V s and low carrier density on the order of ∼10^{12} cm^{-2}. Along with unambiguous Shubnikov-de Haas oscillations, the spacing of the quantized Hall resistance suggests that the interface is comprised of a single quantum well with ten parallel conducting two-dimensional sub-bands. This provides new insight into the electronic structure of conducting oxide interfaces and represents an important step towards designing and understanding advanced oxide devices.
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Affiliation(s)
- Felix Trier
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - Guenevere E D K Prawiroatmodjo
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Zhicheng Zhong
- Max Planck Institute for Solid State Research, D-70569 Stuttgart, Germany
| | - Dennis Valbjørn Christensen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - Merlin von Soosten
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Arghya Bhowmik
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - Juan Maria García Lastra
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - Yunzhong Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
| | - Thomas Sand Jespersen
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Nini Pryds
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000 Roskilde, Denmark
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23
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Frenkel Y, Haham N, Shperber Y, Bell C, Xie Y, Chen Z, Hikita Y, Hwang HY, Kalisky B. Anisotropic Transport at the LaAlO3/SrTiO3 Interface Explained by Microscopic Imaging of Channel-Flow over SrTiO3 Domains. ACS APPLIED MATERIALS & INTERFACES 2016; 8:12514-9. [PMID: 27111600 PMCID: PMC5301281 DOI: 10.1021/acsami.6b01655] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 04/25/2016] [Indexed: 05/22/2023]
Abstract
Oxide interfaces, including the LaAlO3/SrTiO3 interface, have been a subject of intense interest for over a decade due to their rich physics and potential as low-dimensional nanoelectronic systems. The field has reached the stage where efforts are invested in developing devices. It is critical now to understand the functionalities and limitations of such devices. Recent scanning probe measurements of the LaAlO3/SrTiO3 interface have revealed locally enhanced current flow and accumulation of charge along channels related to SrTiO3 structural domains. These observations raised a key question regarding the role these modulations play in the macroscopic properties of devices. Here we show that the microscopic picture, mapped by scanning superconducting quantum interference device, accounts for a substantial part of the macroscopically measured transport anisotropy. We compared local flux data with transport values, measured simultaneously, over various SrTiO3 domain configurations. We show a clear relation between maps of local current density over specific domain configurations and the measured anisotropy for the same device. The domains divert the direction of current flow, resulting in a direction-dependent resistance. We also show that the modulation can be significant and that in some cases up to 95% of the current is modulated over the channels. The orientation and distribution of the SrTiO3 structural domains change between different cooldowns of the same device or when electric fields are applied, affecting the device behavior. Our results, highlight the importance of substrate physics, and in particular, the role of structural domains, in controlling electronic properties of LaAlO3/SrTiO3 devices. Furthermore, these results point to new research directions, exploiting the STO domains' ability to divert or even carry current.
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Affiliation(s)
- Yiftach Frenkel
- Department of Physics
and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Noam Haham
- Department of Physics
and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Yishai Shperber
- Department of Physics
and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Christopher Bell
- H. H. Wills Physics Laboratory, University
of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
| | - Yanwu Xie
- Stanford Institute for Materials and Energy
Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Zhuoyu Chen
- Department of Applied Physics, Geballe
Laboratory for Advanced Materials, Stanford
University 476 Lomita
Mall, Stanford University, Stanford, California 94305, United States
| | - Yasuyuki Hikita
- Stanford Institute for Materials and Energy
Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Harold Y. Hwang
- Stanford Institute for Materials and Energy
Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Applied Physics, Geballe
Laboratory for Advanced Materials, Stanford
University 476 Lomita
Mall, Stanford University, Stanford, California 94305, United States
| | - Beena Kalisky
- Department of Physics
and Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel
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24
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Zeng S, Lü W, Huang Z, Liu Z, Han K, Gopinadhan K, Li C, Guo R, Zhou W, Ma HH, Jian L, Venkatesan T. Liquid-Gated High Mobility and Quantum Oscillation of the Two-Dimensional Electron Gas at an Oxide Interface. ACS NANO 2016; 10:4532-4537. [PMID: 26974812 DOI: 10.1021/acsnano.6b00409] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electric field effect in electronic double layer transistor (EDLT) configuration with ionic liquids as the dielectric materials is a powerful means of exploring various properties in different materials. Here, we demonstrate the modulation of electrical transport properties and extremely high mobility of two-dimensional electron gas at LaAlO3/SrTiO3 (LAO/STO) interface through ionic liquid-assisted electric field effect. With a change of the gate voltages, the depletion of charge carrier and the resultant enhancement of electron mobility up to 19 380 cm(2)/(V s) are realized, leading to quantum oscillations of the conductivity at the LAO/STO interface. The present results suggest that high-mobility oxide interfaces, which exhibit quantum phenomena, could be obtained by ionic liquid-assisted field effect.
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Affiliation(s)
- Shengwei Zeng
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Weiming Lü
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Zhen Huang
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Zhiqi Liu
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Kun Han
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Kalon Gopinadhan
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Changjian Li
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore
| | - Rui Guo
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore
| | - Wenxiong Zhou
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Haijiao Harsan Ma
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
| | - Linke Jian
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
| | - Thirumalai Venkatesan
- NUSNNI-NanoCore, National University of Singapore , Singapore 117411, Singapore
- Department of Physics, National University of Singapore , Singapore 117542, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore
- Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore
- Department of Electrical and Computer Engineering, National University of Singapore , Singapore 117576, Singapore
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25
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Huang Z, Han K, Zeng S, Motapothula M, Borisevich AY, Ghosh S, Lü W, Li C, Zhou W, Liu Z, Coey M, Venkatesan T. The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces. NANO LETTERS 2016; 16:2307-2313. [PMID: 26959195 DOI: 10.1021/acs.nanolett.5b04814] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Since the discovery of two-dimensional electron gas (2DEG) at the oxide interface of LaAlO3/SrTiO3 (LAO/STO), improving carrier mobility has become an important issue for device applications. In this paper, by using an alternate polar perovskite insulator (La0.3Sr0.7) (Al0.65Ta0.35)O3 (LSAT) for reducing lattice mismatch from 3.0% to 1.0%, the low-temperature carrier mobility has been increased 30 fold to 35,000 cm(2) V(-1) s(-1). Moreover, two critical thicknesses for the LSAT/STO (001) interface are found, one at 5 unit cells for appearance of the 2DEG and the other at 12 unit cells for a peak in the carrier mobility. By contrast, the conducting (110) and (111) LSAT/STO interfaces only show a single critical thickness of 8 unit cells. This can be explained in terms of polar fluctuation arising from LSAT chemical composition. In addition to lattice mismatch and crystal symmetry at the interface, polar fluctuation arising from composition has been identified as an important variable to be tailored at the oxide interfaces to optimize the 2DEG transport.
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Affiliation(s)
- Zhen Huang
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- Department of Physics, National University of Singapore , 117542 Singapore
| | - Kun Han
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- Department of Physics, National University of Singapore , 117542 Singapore
| | - Shengwei Zeng
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- Department of Physics, National University of Singapore , 117542 Singapore
| | - Mallikarjuna Motapothula
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- Department of Physics, National University of Singapore , 117542 Singapore
| | | | - Saurabh Ghosh
- Department of Physics and Astronomy, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Weiming Lü
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology , Harbin 150081, People's Republic of China
| | - Changjian Li
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
| | - Wenxiong Zhou
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- Department of Physics, National University of Singapore , 117542 Singapore
| | - Zhiqi Liu
- Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States
| | - Michael Coey
- NUSNNI-NanoCore, National University of Singapore , 117411 Singapore
- School of Physics and CRANN, Trinity College , Dublin 2, Ireland
| | - 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
- Department of Materials Science and Engineering, National University of Singapore , Singapore 117575, Singapore
- National University of Singapore Graduate School for Integrative Sciences and Engineering (NGS) , 28 Medical Drive, Singapore 117456, Singapore
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26
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Conducting LaAlO3/SrTiO3 heterointerfaces on atomically-flat substrates prepared by deionized-water. Sci Rep 2016; 6:23621. [PMID: 27033248 PMCID: PMC4817030 DOI: 10.1038/srep23621] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/11/2016] [Indexed: 11/20/2022] Open
Abstract
We have investigated how the recently-developed water-leaching method for atomically-flat SrTiO3 (STO) substrates affects the transport properties of LaAlO3 (LAO) and STO heterointerfaces. Using pulsed laser deposition at identical growth conditions, we have synthesized epitaxial LAO thin-films on two different STO substrates, which are prepared by water-leaching and buffered hydrofluoric acid (BHF) etching methods. The structural, transport, and optical properties of LAO/STO heterostructures grown on water-leached substrates show the same high-quality as the samples grown on BHF-etched substrates. These results indicate that the water-leaching method can be used to grow complex oxide heterostructures with atomically well-defined heterointerfaces without safety concerns.
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27
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Xu C, Bäumer C, Heinen RA, Hoffmann-Eifert S, Gunkel F, Dittmann R. Disentanglement of growth dynamic and thermodynamic effects in LaAlO3/SrTiO3 heterostructures. Sci Rep 2016; 6:22410. [PMID: 27009359 PMCID: PMC4806350 DOI: 10.1038/srep22410] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/12/2016] [Indexed: 11/14/2022] Open
Abstract
The influence of non-equilibrium and equilibrium processes during growth of LaAlO3/SrTiO3 (LAO/STO) heterostructures is analyzed. We investigate the electronic properties of LAO/STO heterostructures obtained at constant growth conditions after annealing in different oxygen atmospheres within the typical growth window (1 × 10−4 mbar –1 × 10−2 mbar). The variation of annealing conditions is found to cause a similar change of electronic properties as observed for samples grown in different oxygen pressure. The results indicate that equilibrium defect formation is the dominant process for establishing the properties of the two-dimensional electron gas (2DEG), while growth dynamics play a minor role in the typical LAO/STO growth regime. Furthermore, the effects of non-equilibrium processes occurring during growth are investigated in detail by quenching just-grown LAO/STO heterostructures directly after growth. We show that during growth the sample is pushed into a non-equilibrium state. After growth, the sample then relaxes towards equilibrium, while the relaxation rate strongly depends on the ambient pressure. The observed relaxation behavior is mainly associated with a reoxidation of the STO bulk, while the 2DEG is formed immediately after the growth.
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Affiliation(s)
- Chencheng Xu
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Christoph Bäumer
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Ronja Anika Heinen
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | | | - Felix Gunkel
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany.,Institute of Materials in Electrical Engineering and Information Technology II, RWTH Aachen University, 52074 Aachen, Germany
| | - Regina Dittmann
- Peter Grünberg Institute 7, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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28
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Rödel TC, Fortuna F, Sengupta S, Frantzeskakis E, Le Fèvre P, Bertran F, Mercey B, Matzen S, Agnus G, Maroutian T, Lecoeur P, Santander-Syro AF. Universal Fabrication of 2D Electron Systems in Functional Oxides. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:1976-1980. [PMID: 26753522 DOI: 10.1002/adma.201505021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 11/19/2015] [Indexed: 06/05/2023]
Abstract
2D electron systems (2DESs) in functional oxides are promising for applications, but their fabrication and use, essentially limited to SrTiO3 -based heterostructures, are hampered by the need for growing complex oxide overlayers thicker than 2 nm using evolved techniques. It is demonstrated that thermal deposition of a monolayer of an elementary reducing agent suffices to create 2DESs in numerous oxides.
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Affiliation(s)
- Tobias Chris Rödel
- CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, 91405, Orsay, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192, Gif-sur-Yvette, France
| | - Franck Fortuna
- CSNSM, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, 91405, Orsay, France
| | - Shamashis Sengupta
- Laboratoire de Physique des Solides, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | | | - Patrick Le Fèvre
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192, Gif-sur-Yvette, France
| | - François Bertran
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192, Gif-sur-Yvette, France
| | - Bernard Mercey
- CRISMAT, ENSICAEN-CNRS UMR6508, 6 bd. Maréchal Juin, 14050, Caen, France
| | - Sylvia Matzen
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Guillaume Agnus
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Thomas Maroutian
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405, Orsay, France
| | - Philippe Lecoeur
- Institut d'Electronique Fondamentale, Univ. Paris-Sud, CNRS, Université Paris-Saclay, 91405, Orsay, France
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29
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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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30
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Sarantopoulos A, Ferreiro-Vila E, Pardo V, Magén C, Aguirre MH, Rivadulla F. Electronic Degeneracy and Intrinsic Magnetic Properties of EpitaxialNb: SrTiO3 Thin Films Controlled by Defects. PHYSICAL REVIEW LETTERS 2015; 115:166801. [PMID: 26550891 DOI: 10.1103/physrevlett.115.166801] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Indexed: 06/05/2023]
Abstract
We report thermoelectric power experiments in e-doped thin films of SrTiO3 (STO) which demonstrate that the electronic band degeneracy can be lifted through defect management during growth. We show that even small amounts of cationic vacancies, combined with epitaxial stress, produce a homogeneous tetragonal distortion of the films, resulting in a Kondo-like resistance upturn at low temperature, large anisotropic magnetoresistance, and nonlinear Hall effect. Ab initio calculations confirm a different occupation of each band depending on the degree of tetragonal distortion. The phenomenology reported in this Letter for tetragonally distorted e-doped STO thin films, is similar to that observed in LaAlO3/STO interfaces and magnetic STO quantum wells.
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Affiliation(s)
- A Sarantopoulos
- Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain
| | - E Ferreiro-Vila
- Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain
| | - V Pardo
- Departamento de Física Aplicada, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
- Instituto de Investigacións Tecnolóxicas, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - C Magén
- Laboratorio de Microscopás Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
- Fundación ARAID, 50018 Zaragoza, Spain
| | - M H Aguirre
- Laboratorio de Microscopás Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, 50018 Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50009 Zaragoza, Spain
| | - F Rivadulla
- Centro de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain
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31
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Strong correlations elucidate the electronic structure and phase diagram of LaAlO3/SrTiO3 interface. Nat Commun 2015; 6:8239. [PMID: 26359206 PMCID: PMC4647855 DOI: 10.1038/ncomms9239] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 07/30/2015] [Indexed: 11/08/2022] Open
Abstract
The interface between the two band insulators SrTiO3 and LaAlO3 has the unexpected properties of a two-dimensional electron gas. It is even superconducting with a transition temperature, T(c), that can be tuned using gate bias V(g), which controls the number of electrons added or removed from the interface. The gate bias-temperature (V(g), T) phase diagram is characterized by a dome-shaped region where superconductivity occurs, that is, T(c) has a non-monotonic dependence on V(g), similar to many unconventional superconductors. Here, we report, the frequency of the quantum resistance-oscillations versus inverse magnetic field for various V(g). This frequency follows the same non-monotonic behaviour as T(c); a similar trend is seen in the low field limit of the Hall coefficient. We theoretically show that electronic correlations result in a non-monotonic population of the mobile band, which can account for the experimental behaviour of the normal transport properties and the superconducting dome.
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32
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Pallecchi I, Telesio F, Li D, Fête A, Gariglio S, Triscone JM, Filippetti A, Delugas P, Fiorentini V, Marré D. Giant oscillating thermopower at oxide interfaces. Nat Commun 2015; 6:6678. [PMID: 25813265 PMCID: PMC4389223 DOI: 10.1038/ncomms7678] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 02/18/2015] [Indexed: 11/09/2022] Open
Abstract
Understanding the nature of charge carriers at the LaAlO3/SrTiO3 interface is one of the major open issues in the full comprehension of the charge confinement phenomenon in oxide heterostructures. Here, we investigate thermopower to study the electronic structure in LaAlO3/SrTiO3 at low temperature as a function of gate field. In particular, under large negative gate voltage, corresponding to the strongly depleted charge density regime, thermopower displays high negative values of the order of 10(4)-10(5) μVK(-1), oscillating at regular intervals as a function of the gate voltage. The huge thermopower magnitude can be attributed to the phonon-drag contribution, while the oscillations map the progressive depletion and the Fermi level descent across a dense array of localized states lying at the bottom of the Ti 3d conduction band. This study provides direct evidence of a localized Anderson tail in the two-dimensional electron liquid at the LaAlO3/SrTiO3 interface.
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Affiliation(s)
- Ilaria Pallecchi
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
| | - Francesca Telesio
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
| | - Danfeng Li
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Alexandre Fête
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Stefano Gariglio
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Jean-Marc Triscone
- Department of Quantum Matter Physics,, University of Geneva, 24 Quai E.-Ansermet, Geneva 4 1211, Switzerland
| | - Alessio Filippetti
- CNR-IOM UOS Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, S.P. Monserrato-Sestu Km.0,700, Monserrato (Ca) 09042, Italy
| | - Pietro Delugas
- CompuNet, Istituto Italiano di Tecnologia—IIT, Via Morego 30, Genova 16163, Italy
| | - Vincenzo Fiorentini
- Dipartimento di Fisica, Università di Cagliari, CNR-IOM, S.P. Monserrato-Sestu Km.0,700, Monserrato (Ca) 09042, Italy
| | - Daniele Marré
- Department of Physics, CNR-SPIN and Genova University, via Dodecaneso 33, Genova 16146, Italy
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33
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A high-mobility electronic system at an electrolyte-gated oxide surface. Nat Commun 2015; 6:6437. [PMID: 25762485 PMCID: PMC4382703 DOI: 10.1038/ncomms7437] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/28/2015] [Indexed: 11/29/2022] Open
Abstract
Electrolyte gating is a powerful technique for accumulating large carrier densities at a surface. Yet this approach suffers from significant sources of disorder: electrochemical reactions can damage or alter the sample, and the ions of the electrolyte and various dissolved contaminants sit Angstroms from the electron system. Accordingly, electrolyte gating is well suited to studies of superconductivity and other phenomena robust to disorder, but of limited use when reactions or disorder must be avoided. Here we demonstrate that these limitations can be overcome by protecting the sample with a chemically inert, atomically smooth sheet of hexagonal boron nitride. We illustrate our technique with electrolyte-gated strontium titanate, whose mobility when protected with boron nitride improves more than 10-fold while achieving carrier densities nearing 1014 cm−2. Our technique is portable to other materials, and should enable future studies where high carrier density modulation is required but electrochemical reactions and surface disorder must be minimized. Electrolyte gating enables the accumulation of large carrier densities in two-dimensional electron systems. Here, the authors demonstrate that a few-atom thick layer of hexagonal boron nitride can dramatically improve carrier mobility in an electrolyte-gated system by limiting chemical reactions and disorder.
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Santander-Syro AF, Fortuna F, Bareille C, Rödel TC, Landolt G, Plumb NC, Dil JH, Radović M. Giant spin splitting of the two-dimensional electron gas at the surface of SrTiO3. NATURE MATERIALS 2014; 13:1085-1090. [PMID: 25306421 DOI: 10.1038/nmat4107] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 09/05/2014] [Indexed: 06/04/2023]
Abstract
Two-dimensional electron gases (2DEGs) forming at the interfaces of transition metal oxides exhibit a range of properties, including tunable insulator-superconductor-metal transitions, large magnetoresistance, coexisting ferromagnetism and superconductivity, and a spin splitting of a few meV (refs 10, 11). Strontium titanate (SrTiO3), the cornerstone of such oxide-based electronics, is a transparent, non-magnetic, wide-bandgap insulator in the bulk, and has recently been found to host a surface 2DEG (refs 12-15). The most strongly confined carriers within this 2DEG comprise two subbands, separated by an energy gap of 90 meV and forming concentric circular Fermi surfaces. Using spin- and angle-resolved photoemission spectroscopy (SARPES), we show that the electron spins in these subbands have opposite chiralities. Although the Rashba effect might be expected to give rise to such spin textures, the giant splitting of almost 100 meV at the Fermi level is far larger than anticipated. Moreover, in contrast to a simple Rashba system, the spin-polarized subbands are non-degenerate at the Brillouin zone centre. This degeneracy can be lifted by time-reversal symmetry breaking, implying the possible existence of magnetic order. These results show that confined electronic states at oxide surfaces can be endowed with novel, non-trivial properties that are both theoretically challenging to anticipate and promising for technological applications.
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Affiliation(s)
- A F Santander-Syro
- CSNSM, Université Paris-Sud and CNRS/IN2P3, Bâtiments 104 et 108, 91405 Orsay cedex, France
| | - F Fortuna
- CSNSM, Université Paris-Sud and CNRS/IN2P3, Bâtiments 104 et 108, 91405 Orsay cedex, France
| | - C Bareille
- CSNSM, Université Paris-Sud and CNRS/IN2P3, Bâtiments 104 et 108, 91405 Orsay cedex, France
| | - T C Rödel
- 1] CSNSM, Université Paris-Sud and CNRS/IN2P3, Bâtiments 104 et 108, 91405 Orsay cedex, France [2] Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, 91192 Gif-sur-Yvette, France
| | - G Landolt
- 1] Physik-Institut, Universität Zürich, Winterthurerstrasse 190 8057 Zürich, Switzerland [2] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - J H Dil
- 1] Physik-Institut, Universität Zürich, Winterthurerstrasse 190 8057 Zürich, Switzerland [2] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland [3] Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - M Radović
- 1] Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland [2] Institute of Condensed Matter Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland [3] SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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35
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Ron A, Maniv E, Graf D, Park JH, Dagan Y. Anomalous magnetic ground state in an LaAlO3/SrTiO3 interface probed by transport through nanowires. PHYSICAL REVIEW LETTERS 2014; 113:216801. [PMID: 25479513 DOI: 10.1103/physrevlett.113.216801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Indexed: 06/04/2023]
Abstract
Resistance as a function of temperature down to 20 mK and magnetic fields up to 18 T for various carrier concentrations is measured for nanowires made from the SrTiO3/LaAlO3 interface using a hard mask shadow deposition technique. The narrow width of the wires (of the order of 50 nm) allows us to separate out the magnetic effects from the dominant superconducting ones at low magnetic fields. At this regime hysteresis loops are observed along with the superconducting transition. From our data analysis, we find that the magnetic order probed by the giant magnetoresistance effect vanishes at TCurie=954±20 mK. This order is not a simple ferromagnetic state but consists of domains with opposite magnetization having a preferred in-plane orientation.
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Affiliation(s)
- A Ron
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - E Maniv
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 69978, Israel
| | - D Graf
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - J-H Park
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Y Dagan
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel Aviv, 69978, Israel
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36
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Suppression of the critical thickness threshold for conductivity at the LaAlO3/SrTiO3 interface. Nat Commun 2014; 5:4291. [DOI: 10.1038/ncomms5291] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 06/04/2014] [Indexed: 11/09/2022] Open
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37
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Long-range electronic reconstruction to a dxz,yz-dominated Fermi surface below the LaAlO₃/SrTiO₃ interface. Sci Rep 2014; 4:5338. [PMID: 24939804 PMCID: PMC4061544 DOI: 10.1038/srep05338] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 05/27/2014] [Indexed: 11/08/2022] Open
Abstract
Low dimensionality, broken symmetry and easily-modulated carrier concentrations provoke novel electronic phase emergence at oxide interfaces. However, the spatial extent of such reconstructions - i.e. the interfacial "depth" - remains unclear. Examining LaAlO₃/SrTiO₃ heterostructures at previously unexplored carrier densities n(2D) ≥ 6.9 × 10(14) cm(-2), we observe a Shubnikov-de Haas effect for small in-plane fields, characteristic of an anisotropic 3D Fermi surface with preferential dxz,yz orbital occupancy extending over at least 100 nm perpendicular to the interface. Quantum oscillations from the 3D Fermi surface of bulk doped SrTiO₃ emerge simultaneously at higher n(2D). We distinguish three areas in doped perovskite heterostructures: narrow (<20 nm) 2D interfaces housing superconductivity and/or other emergent phases, electronically isotropic regions far (>120 nm) from the interface and new intermediate zones where interfacial proximity renormalises the electronic structure relative to the bulk.
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38
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Chen YZ, Bovet N, Kasama T, Gao WW, Yazdi S, Ma C, Pryds N, Linderoth S. Room temperature formation of high-mobility two-dimensional electron gases at crystalline complex oxide interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:1462-1467. [PMID: 24338762 DOI: 10.1002/adma.201304634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Indexed: 06/03/2023]
Abstract
Well-controlled sub-unit-cell layer-bylayer epitaxial growth of spinel alumina is achieved at room temperature on a TiO2 -terminated SrTiO3 single-crystalline substrate. By tailoring the interface redox reaction, 2D electron gases with mobilities exceeding 3000 cm 2 V(-1) s(-1) are achieved at this novel oxide interface.
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Affiliation(s)
- Y Z Chen
- Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, 4000, Roskilde, Denmark
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39
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Kalisky B, Spanton EM, Noad H, Kirtley JR, Nowack KC, Bell C, Sato HK, Hosoda M, Xie Y, Hikita Y, Woltmann C, Pfanzelt G, Jany R, Richter C, Hwang HY, Mannhart J, Moler KA. Locally enhanced conductivity due to the tetragonal domain structure in LaAlO3/SrTiO3 heterointerfaces. NATURE MATERIALS 2013; 12:1091-1095. [PMID: 24013791 DOI: 10.1038/nmat3753] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 08/06/2013] [Indexed: 06/02/2023]
Abstract
The ability to control materials properties through interface engineering is demonstrated by the appearance of conductivity at the interface of certain insulators, most famously the {001} interface of the band insulators LaAlO3 and TiO2-terminated SrTiO3 (STO; refs 1, 2). Transport and other measurements in this system show a plethora of diverse physical phenomena. To better understand the interface conductivity, we used scanning superconducting quantum interference device microscopy to image the magnetic field locally generated by current in an interface. At low temperature, we found that the current flowed in conductive narrow paths oriented along the crystallographic axes, embedded in a less conductive background. The configuration of these paths changed on thermal cycling above the STO cubic-to-tetragonal structural transition temperature, implying that the local conductivity is strongly modified by the STO tetragonal domain structure. The interplay between substrate domains and the interface provides an additional mechanism for understanding and controlling the behaviour of heterostructures.
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Affiliation(s)
- Beena Kalisky
- 1] Department of Applied Physics, Stanford University, Stanford, California 94305, USA [2] Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel [3]
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40
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Lu HL, Liao ZM, Zhang L, Yuan WT, Wang Y, Ma XM, Yu DP. Reversible insulator-metal transition of LaAlO₃/SrTiO₃ interface for nonvolatile memory. Sci Rep 2013; 3:2870. [PMID: 24100438 PMCID: PMC3792417 DOI: 10.1038/srep02870] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 09/19/2013] [Indexed: 11/12/2022] Open
Abstract
We report a new type of memory device based on insulating LaAlO3/SrTiO3 (LAO/STO) hetero-interface. The microstructures of the LAO/STO interface are characterized by Cs-corrected scanning transmission electron microscopy, which reveals the element intermixing at the interface. The inhomogeneous element distribution may result in carrier localization, which is responsible for the insulating state. The insulating state of such interface can be converted to metallic state by light illumination and the metallic state maintains after light off due to giant persistent photoconductivity (PPC) effect. The on/off ratio between the PPC and the initial dark conductance is as large as 105. The metallic state also can be converted back to insulating state by applying gate voltage. Reversible and reproducible resistive switching makes LAO/STO interface promising as a nonvolatile memory. Our results deepen the understanding of PPC phenomenon in LAO/STO, and pave the way for the development of all-oxide electronics integrating information storage devices.
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Affiliation(s)
- Hong-Liang Lu
- State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, P.R. China
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41
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Chen YZ, Bovet N, Trier F, Christensen DV, Qu FM, Andersen NH, Kasama T, Zhang W, Giraud R, Dufouleur J, Jespersen TS, Sun JR, Smith A, Nygård J, Lu L, Büchner B, Shen BG, Linderoth S, Pryds N. A high-mobility two-dimensional electron gas at the spinel/perovskite interface of γ-Al2O3/SrTiO3. Nat Commun 2013; 4:1371. [DOI: 10.1038/ncomms2394] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 12/17/2012] [Indexed: 11/09/2022] Open
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42
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Laukhin V, Copie O, Rozenberg MJ, Weht R, Bouzehouane K, Reyren N, Jacquet E, Bibes M, Barthélémy A, Herranz G. Electronic subband reconfiguration in a d0-perovskite induced by strain-driven structural transformations. PHYSICAL REVIEW LETTERS 2012; 109:226601. [PMID: 23368143 DOI: 10.1103/physrevlett.109.226601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 06/19/2012] [Indexed: 06/01/2023]
Abstract
It is well known that transport in lightly n-doped SrTiO(3) involves light and heavy electron bands. We have found that upon application of moderate quasi-isotropic pressures, the relative positions of these subbands are changed by a few meV and, eventually, a band inversion occurs at ~1 kbar. Such effects are, however, suppressed in the closely related KTaO(3) perovskite. We show that the extremely subtle electronic reconfiguration in SrTiO(3) is triggered by strain-induced structural transformations that are accompanied by remarkable mobility enhancements up to about Δμ/μ≈300%. Our results provide a microscopic rationale for the recently discovered transport enhancement under strain and underscore the role of the internal structural degrees of freedom in the modulation of the perovskite electronic properties.
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Affiliation(s)
- V Laukhin
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, Bellaterra 08193, Catalonia, Spain
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43
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Bibes M, Reyren N, Lesne E, George JM, Deranlot C, Collin S, Barthélémy A, Jaffrès H. Towards electrical spin injection into LaAlO3-SrTiO3. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:4958-4971. [PMID: 22987038 DOI: 10.1098/rsta.2012.0201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Future spintronics devices will be built from elemental blocks allowing the electrical injection, propagation, manipulation and detection of spin-based information. Owing to their remarkable multi-functional and strongly correlated character, oxide materials already provide such building blocks for charge-based devices such as ferroelectric field-effect transistors (FETs), as well as for spin-based two-terminal devices such as magnetic tunnel junctions, with giant responses in both cases. Until now, the lack of suitable channel materials and the uncertainty of spin-injection conditions in these compounds had however prevented the exploration of similar giant responses in oxide-based lateral spin transport structures. In this paper, we discuss the potential of oxide-based spin FETs and report magnetotransport data that suggest electrical spin injection into the LaAlO(3)-SrTiO(3) interface system. In a local, three-terminal measurement scheme, we analyse the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or longitudinal magnetic fields (Hanle and 'inverted' Hanle effects). The spin accumulation signal appears to be much larger than expected, probably owing to amplification effects by resonant tunnelling through localized states in the LaAlO(3). We give perspectives on how to achieve direct spin injection with increased detection efficiency, as well on the implementation of efficient top gating schemes for spin manipulation.
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Affiliation(s)
- M Bibes
- Unité Mixte de Physique CNRS-Thales, Palaiseau, France.
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44
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A universal critical density underlying the physics of electrons at the LaAlO3/SrTiO3 interface. Nat Commun 2012; 3:1129. [DOI: 10.1038/ncomms2116] [Citation(s) in RCA: 253] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 09/04/2012] [Indexed: 11/08/2022] Open
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45
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Kalisky B, Bert JA, Klopfer BB, Bell C, Sato HK, Hosoda M, Hikita Y, Hwang HY, Moler KA. Critical thickness for ferromagnetism in LaAlO3/SrTiO3 heterostructures. Nat Commun 2012; 3:922. [DOI: 10.1038/ncomms1931] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 05/28/2012] [Indexed: 11/09/2022] Open
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46
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Au K, Li DF, Chan NY, Dai JY. Polar liquid molecule induced transport property modulation at LaAlO₃/SrTiO₃ heterointerface. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2012; 24:2598-2602. [PMID: 22495936 DOI: 10.1002/adma.201200673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Indexed: 05/31/2023]
Affiliation(s)
- K Au
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China
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47
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Michaeli K, Potter AC, Lee PA. Superconducting and ferromagnetic phases in SrTiO3/LaAlO3 oxide interface structures: possibility of finite momentum pairing. PHYSICAL REVIEW LETTERS 2012; 108:117003. [PMID: 22540501 DOI: 10.1103/physrevlett.108.117003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Indexed: 05/31/2023]
Abstract
We introduce a model to explain the observed ferromagnetism and superconductivity in LAO/STO oxide interface structures. Because of the polar catastrophe mechanism, 1/2 charge per unit cell is transferred to the interface layer. We argue that this charge localizes and orders ferromagnetically via exchange with the conduction electrons. Ordinarily, this ferromagnetism would destroy superconductivity, but, due to strong spin-orbit coupling near the interface, the magnetism and superconductivity can coexist by forming a Fulde-Ferrell-Larkin-Ovchinikov-type condensate of Cooper pairs at finite momentum, which is surprisingly robust in the presence of strong disorder.
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Affiliation(s)
- Karen Michaeli
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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48
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Lee M, Williams JR, Zhang S, Frisbie CD, Goldhaber-Gordon D. Electrolyte gate-controlled Kondo effect in SrTiO3. PHYSICAL REVIEW LETTERS 2011; 107:256601. [PMID: 22243097 DOI: 10.1103/physrevlett.107.256601] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Indexed: 05/31/2023]
Abstract
We report low-temperature, high-field magnetotransport measurements of SrTiO(3) gated by an ionic gel electrolyte. A saturating resistance upturn and negative magnetoresistance that signal the emergence of the Kondo effect appear for higher applied gate voltages. This observation, enabled by the wide tunability of the ionic gel-applied electric field, promotes the interpretation of the electric field-effect-induced 2D electron system in SrTiO(3) as an admixture of magnetic Ti(3+) ions, i.e., localized and unpaired electrons, and delocalized electrons that partially fill the Ti 3d conduction band.
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Affiliation(s)
- Menyoung Lee
- Department of Physics, Stanford University, Stanford, California 94305, USA
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49
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Kim M, Bell C, Kozuka Y, Kurita M, Hikita Y, Hwang HY. Fermi surface and superconductivity in low-density high-mobility δ-doped SrTiO3. PHYSICAL REVIEW LETTERS 2011; 107:106801. [PMID: 21981518 DOI: 10.1103/physrevlett.107.106801] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Indexed: 05/31/2023]
Abstract
The electronic structure of low-density n-type SrTiO3 δ-doped heterostructures is investigated by angular dependent Shubnikov-de Haas oscillations. In addition to a controllable crossover from a three- to two-dimensional Fermi surface, clear beating patterns for decreasing dopant layer thicknesses are found. These indicate the lifting of the degeneracy of the conduction band due to subband quantization in the two-dimensional limit. Analysis of the temperature-dependent oscillations shows that similar effective masses are found for all components, associated with the splitting of the light electron pocket. The dimensionality crossover in the superconducting state is found to be distinct from the normal state, resulting in a rich phase diagram as a function of dopant layer thickness.
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Affiliation(s)
- M Kim
- Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan
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