1
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Tunable superconductivity and its origin at KTaO 3 interfaces. Nat Commun 2023; 14:951. [PMID: 36806127 PMCID: PMC9941122 DOI: 10.1038/s41467-023-36309-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 01/23/2023] [Indexed: 02/22/2023] Open
Abstract
What causes Cooper pairs to form in unconventional superconductors is often elusive because experimental signatures that connect to a specific pairing mechanism are rare. Here, we observe distinct dependences of the superconducting transition temperature Tc on carrier density n2D for electron gases formed at KTaO3 (111), (001) and (110) interfaces. For the (111) interface, a remarkable linear dependence of Tc on n2D is observed over a range of nearly one order of magnitude. Further, our study of the dependence of superconductivity on gate electric fields reveals the role of the interface in mediating superconductivity. We find that the extreme sensitivity of superconductivity to crystallographic orientation can be explained by pairing via inter-orbital interactions induced by an inversion-breaking transverse optical phonon and quantum confinement. This mechanism is also consistent with the dependence of Tc on n2D. Our study may shed light on the pairing mechanism in other superconducting quantum paraelectrics.
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2
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Maurel L, Herrero-Martín J, Motti F, Vasili HB, Piamonteze C, Heyderman LJ, Scagnoli V. Route to tunable room temperature electric polarization in SrTiO 3-CoFe 2O 4 heterostructures. JOURNAL OF MATERIALS CHEMISTRY. C 2021; 9:5977-5984. [PMID: 34094567 PMCID: PMC8118119 DOI: 10.1039/d0tc05821a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Utilizing the magnetostrictive properties of CoFe2O4, we demonstrate reversible room temperature control of the Ti electronic structure in SrTiO3-CoFe2O4 heterostructures, by inducing local and reversible strain in the SrTiO3. By means of X-ray absorption spectroscopy, we have ascertained the changes that take place in the energy levels of the Ti 3d orbitals under the influence of an external magnetic field. The observed Ti electronic state when the sample is subjected to moderately large external magnetic fields and the disappearance of the induced phase upon their removal indicates lattice distortions that are suggestive of the development of a net electric polarization.
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Affiliation(s)
- Laura Maurel
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | | | - Federico Motti
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | - Hari Babu Vasili
- ALBA Synchrotron Light Source 08290 Cerdanyola del Vallès Barcelona Spain
| | | | - Laura J Heyderman
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
| | - Valerio Scagnoli
- Laboratory for Mesoscopic Systems, Department of Materials, ETH Zurich 8093 Zurich Switzerland
- Paul Scherrer Institute 5232 Villigen PSI Switzerland
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3
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Zwiebler M, Di Gennaro E, Hamann-Borrero JE, Ritschel T, Green RJ, Sawatzky GA, Schierle E, Weschke E, Leo A, Granozio FM, Geck J. Transition from a uni- to a bimodal interfacial charge distribution in [Formula: see text]/[Formula: see text] upon cooling. Sci Rep 2020; 10:18359. [PMID: 33110119 PMCID: PMC7591581 DOI: 10.1038/s41598-020-74364-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 09/17/2020] [Indexed: 11/09/2022] Open
Abstract
We present a combined resonant soft X-ray reflectivity and electric transport study of [Formula: see text]/[Formula: see text] field effect devices. The depth profiles with atomic layer resolution that are obtained from the resonant reflectivity reveal a pronounced temperature dependence of the two-dimensional electron liquid at the [Formula: see text]/[Formula: see text] interface. At room temperature the corresponding electrons are located close to the interface, extending down to 4 unit cells into the [Formula: see text] substrate. Upon cooling, however, these interface electrons assume a bimodal depth distribution: They spread out deeper into the [Formula: see text] and split into two distinct parts, namely one close to the interface with a thickness of about 4 unit cells and another centered around 9 unit cells from the interface. The results are consistent with theoretical predictions based on oxygen vacancies at the surface of the [Formula: see text] film and support the notion of a complex interplay between structural and electronic degrees of freedom.
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Affiliation(s)
- M. Zwiebler
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - E. Di Gennaro
- Dipartimento di Fisica “E. Pancini”, Università di Napoli “Federico II”, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - J. E. Hamann-Borrero
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - T. Ritschel
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
| | - R. J. Green
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, V6T 1Z1 Canada
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, S7N 5E2 Canada
| | - G. A. Sawatzky
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, V6T 1Z1 Canada
| | - E. Schierle
- Helmholtz-Zentrum Berlin, BESSY, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - E. Weschke
- Helmholtz-Zentrum Berlin, BESSY, Albert-Einstein-Str. 15, 12489 Berlin, Germany
| | - A. Leo
- Dipartimento di Fisica “E. R. Caianiello”, Università degli Studi di Salerno, Fisciano, Italy
- CNR-SPIN, Campus di Fisciano-Salerno, Fisciano, Italy
| | - F. Miletto Granozio
- CNR-SPIN, Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Naples, Italy
| | - J. Geck
- Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
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4
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Rubano A, Scigaj M, Sánchez F, Herranz G, Paparo D. Optical second harmonic generation from LaAlO 3/SrTiO 3 interfaces with different in-plane anisotropies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:135001. [PMID: 31778975 DOI: 10.1088/1361-648x/ab5ccc] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Oxide growth with semiconductor-like accuracy allows the fabrication of atomically precise thin films and interfaces displaying a wide range of phases and functionalities that are absent in the corresponding oxide bulk materials. Among the other properties it was found that a two-dimensional electronic gas is formed under some circumstances at the LaAlO3/SrTiO3(0 0 1) interface separating two typical insulating perovskite crystals. The origin of this conducting state has been discussed at length, since different doping mechanisms can act in these material systems. Many experimental results point to the so-called polar catastrophe scenario as the principal mechanism driving the formation of the two-dimensional electronic gas. According to this mechanism, the existence of an interfacial polar discontinuity is the key ingredient to drive an electronic reconstruction at the LaAlO3/SrTiO3(0 0 1) interface and the consequent formation of a two-dimensional electron gas. This simple picture has been often questioned by the existence of material systems whose interface are predicted being non-polar according to the simplistic 'ionic' limit but that display an electrical behavior analogous to that of LaAlO3/SrTiO3(0 0 1) interfaces. This is the case of the LaAlO3/SrTiO3(1 1 0), i.e., a LaAlO3/SrTiO3 interface with a different in-plane orientation. It is evident that to solve such kind of controversies a detailed investigation of the polar or non-polar state of these interfaces is needed, although this is not simple for the lack of experimental tools that are specifically sensitive to interfacial polarity. Here we apply Optical Second Harmonic Generation to investigate LaAlO3/SrTiO3 interfaces with different in-plane orientations to bridge this gap. By comparing our results with recent theoretical findings, we will arrive to the conclusion that the real LaAlO3/SrTiO3(1 1 0) interface is strongly polar.
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Affiliation(s)
- Andrea Rubano
- Dipartimento di Fisica 'Ettore Pancini', Università di Napoli 'Federico II', Complesso universitario di Monte Sant'Angelo, via Cintia, 80126 Napoli, Italy
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5
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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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6
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Kang KT, Park J, Suh D, Choi WS. Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1803732. [PMID: 30589101 DOI: 10.1002/adma.201803732] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/18/2018] [Indexed: 05/28/2023]
Abstract
The marriage between a 2D layered material (2DLM) and a complex transition metal oxide (TMO) results in a variety of physical and chemical phenomena that cannot be achieved in either material alone. Interesting recent discoveries in systems such as graphene/SrTiO3 , graphene/LaAlO3 /SrTiO3 , graphene/ferroelectric oxide, MoS2 /SrTiO3 , and FeSe/SrTiO3 heterostructures include voltage scaling in field-effect transistors, charge state coupling across an interface, quantum conductance probing of the electrochemical activity, novel memory functions based on charge traps, and greatly enhanced superconductivity. In this context, various properties and functionalities appearing in numerous different 2DLM/TMO heterostructure systems are reviewed. The results imply that the multidimensional heterostructure approach based on the disparate material systems leads to an entirely new platform for the study of condensed matter physics and materials science. The heterostructures are also highly relevant technologically as each constituent material is a promising candidate for next-generation optoelectronic devices.
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Affiliation(s)
- Kyeong Tae Kang
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea
| | - Jeongmin Park
- Department of Energy Sciences, Sungkyunkwan University, Suwon, 16419, Korea
| | - Dongseok Suh
- Department of Energy Sciences, Sungkyunkwan University, Suwon, 16419, Korea
| | - Woo Seok Choi
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Korea
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7
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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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8
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Wang L, Pan W, Hu WX, Sun DY. Strain-induced indirect-to-direct bandgap transition in an np-type LaAlO 3/SrTiO 3(110) superlattice. Phys Chem Chem Phys 2019; 21:7075-7082. [DOI: 10.1039/c8cp07761d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By applying uniaxial in-plane strains, an indirect-to-direct bandgap transition occurs in the polar LaAlO3/SrTiO3 (110) superlattices.
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Affiliation(s)
- L. Wang
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - W. Pan
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - W. X. Hu
- The computer Center
- East China Normal University
- Shanghai 200241
- People's Republic of China
| | - D. Y. Sun
- Department of Physics
- East China Normal University
- Shanghai 200241
- People's Republic of China
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9
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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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10
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Song K, Ryu S, Lee H, Paudel TR, Koch CT, Park B, Lee JK, Choi SY, Kim YM, Kim JC, Jeong HY, Rzchowski MS, Tsymbal EY, Eom CB, Oh SH. Direct imaging of the electron liquid at oxide interfaces. NATURE NANOTECHNOLOGY 2018; 13:198-203. [PMID: 29402977 DOI: 10.1038/s41565-017-0040-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 12/04/2017] [Indexed: 06/07/2023]
Abstract
The breaking of symmetry across an oxide heterostructure causes the electronic orbitals to be reconstructed at the interface into energy states that are different from their bulk counterparts 1 . The detailed nature of the orbital reconstruction critically affects the spatial confinement and the physical properties of the electrons occupying the interfacial orbitals2-4. Using an example of two-dimensional electron liquids forming at LaAlO3/SrTiO3 interfaces5,6 with different crystal symmetry, we show that the selective orbital occupation and spatial quantum confinement of electrons can be resolved with subnanometre resolution using inline electron holography. For the standard (001) interface, the charge density map obtained by inline electron holography shows that the two-dimensional electron liquid is confined to the interface with narrow spatial extension (~1.0 ± 0.3 nm in the half width). On the other hand, the two-dimensional electron liquid formed at the (111) interface shows a much broader spatial extension (~3.3 ± 0.3 nm) with the maximum density located ~2.4 nm away from the interface, in excellent agreement with density functional theory calculations.
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Affiliation(s)
- Kyung Song
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon, Republic of Korea
| | - Sangwoo Ryu
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Hyungwoo Lee
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Tula R Paudel
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | - Christoph T Koch
- Department of Physics, Humboldt University of Berlin, Berlin, Germany
| | - Bumsu Park
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Republic of Korea
| | - Ja Kyung Lee
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Si-Young Choi
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
- Materials Modeling and Characterization Department, Korea Institute of Materials Science (KIMS), Changwon, Republic of Korea
| | - Young-Min Kim
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Republic of Korea
- Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Suwon, Republic of Korea
| | - Jong Chan Kim
- School of Materials Science and Engineering, Ulsan National Institute of Science and Engineering (UNIST), Ulsan, Republic of Korea
| | - Hu Young Jeong
- School of Materials Science and Engineering, Ulsan National Institute of Science and Engineering (UNIST), Ulsan, Republic of Korea
- UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Engineering (UNIST), Ulsan, Republic of Korea
| | - Mark S Rzchowski
- Department of Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Evgeny Y Tsymbal
- Department of Physics and Astronomy & Nebraska Center for Materials and Nanoscience, University of Nebraska, Lincoln, NE, USA
| | - Chang-Beom Eom
- Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Sang Ho Oh
- Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea.
- Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, Republic of Korea.
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11
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Komar P, Jakob G. CADEM: calculate X-ray diffraction of epitaxial multilayers. J Appl Crystallogr 2017; 50:288-292. [PMID: 28190993 PMCID: PMC5294394 DOI: 10.1107/s1600576716018379] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/16/2016] [Indexed: 11/10/2022] Open
Abstract
Epitaxial multilayers and superlattice (SL) structures are gaining increasing importance as they offer the opportunity to create artificial crystals with new functionalities. These crystals deviate from the parent bulk compounds not only in terms of the lattice constants but also in the symmetry classification, which renders calculation of their X-ray diffraction (XRD) patterns tedious. Nevertheless, XRD is essential to get information on the multilayer/SL structure such as, for example, out-of-plane lattice constants, strain relaxation and period length of the crystalline SL. This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary. Moreover, CADEM is very flexible and can be straightforwardly adapted to any material system. The source code of CADEM is available as supporting material for this article.
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Affiliation(s)
- Paulina Komar
- Institute of Physics, University of Mainz, Staudinger Weg 7, 55128 Mainz, Germany; Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
| | - Gerhard Jakob
- Institute of Physics, University of Mainz, Staudinger Weg 7, 55128 Mainz, Germany; Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128 Mainz, Germany
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12
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Gate dependence of upper critical field in superconducting (110) LaAlO3/SrTiO3 interface. Sci Rep 2016; 6:28379. [PMID: 27378271 PMCID: PMC4932507 DOI: 10.1038/srep28379] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 06/03/2016] [Indexed: 11/17/2022] Open
Abstract
The fundamental parameters of the superconducting state such as coherence length and pairing strength are essential for understanding the nature of superconductivity. These parameters can be estimated by measuring critical parameters such as upper critical field, Hc2. In this work, Hc2 of a superconducting (110) LaAlO3/SrTiO3 interface is determined through magnetoresistive measurements as a function of the gate voltage, VG. When VG increases, the critical temperature has a dome-like shape, while Hc2 monotonically decreases. This relationship of independence between the variation of Tc and of Hc2 suggests that the Cooper pairing potential is stronger in the underdoped region and the coherence length increases with the increase of VG. The result is as for high temperature superconducting cuprates and it is different than for conventional low temperature superconductors.
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13
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Cao Y, Yang Z, Kareev M, Liu X, Meyers D, Middey S, Choudhury D, Shafer P, Guo J, Freeland JW, Arenholz E, Gu L, Chakhalian J. Magnetic Interactions at the Nanoscale in Trilayer Titanates. PHYSICAL REVIEW LETTERS 2016; 116:076802. [PMID: 26943550 DOI: 10.1103/physrevlett.116.076802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 06/05/2023]
Abstract
We report on the phase diagram of competing magnetic interactions at the nanoscale in engineered ultrathin trilayer heterostructures of LaTiO_{3}/SrTiO_{3}/YTiO_{3}, in which the interfacial inversion symmetry is explicitly broken. Combined atomic layer resolved scanning transmission electron microscopy with electron energy loss spectroscopy and electrical transport have confirmed the formation of a spatially separated two-dimensional electron liquid and high density two-dimensional localized magnetic moments at the LaTiO_{3}/SrTiO_{3} and SrTiO_{3}/YTiO_{3} interfaces, respectively. Resonant soft x-ray linear dichroism spectroscopy has demonstrated the presence of orbital polarization of the conductive LaTiO_{3}/SrTiO_{3} and localized SrTiO_{3}/YTiO_{3} electrons. Our results provide a route with prospects for exploring new magnetic interfaces, designing a tunable two-dimensional d-electron Kondo lattice, and potential spin Hall applications.
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Affiliation(s)
- Yanwei Cao
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Zhenzhong Yang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
| | - M Kareev
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Xiaoran Liu
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - D Meyers
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - S Middey
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - D Choudhury
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
- Department of Physics, Indian Institute of Technology, Kharagpur 721302, India
| | - P Shafer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Jiandong Guo
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, People's Republic of China
| | - J W Freeland
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - E Arenholz
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Lin Gu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100190, People's Republic of China
| | - J Chakhalian
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
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Herranz G, Singh G, Bergeal N, Jouan A, Lesueur J, Gázquez J, Varela M, Scigaj M, Dix N, Sánchez F, Fontcuberta J. Engineering two-dimensional superconductivity and Rashba spin-orbit coupling in LaAlO₃/SrTiO₃ quantum wells by selective orbital occupancy. Nat Commun 2015; 6:6028. [PMID: 25583368 PMCID: PMC4308716 DOI: 10.1038/ncomms7028] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/03/2014] [Indexed: 11/09/2022] Open
Abstract
The discovery of two-dimensional electron gases (2DEGs) at oxide interfaces-involving electrons in narrow d-bands-has broken new ground, enabling the access to correlated states that are unreachable in conventional semiconductors based on s- and p- electrons. There is a growing consensus that emerging properties at these novel quantum wells-such as 2D superconductivity and magnetism-are intimately connected to specific orbital symmetries in the 2DEG sub-band structure. Here we show that crystal orientation allows selective orbital occupancy, disclosing unprecedented ways to tailor the 2DEG properties. By carrying out electrostatic gating experiments in LaAlO3/SrTiO3 wells of different crystal orientations, we show that the spatial extension and anisotropy of the 2D superconductivity and the Rashba spin-orbit field can be largely modulated by controlling the 2DEG sub-band filling. Such an orientational tuning expands the possibilities for electronic engineering of 2DEGs at LaAlO3/SrTiO3 interfaces.
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Affiliation(s)
- Gervasi Herranz
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Gyanendra Singh
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Nicolas Bergeal
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Alexis Jouan
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Jérôme Lesueur
- LPEM-UMR8213/CNRS-ESPCI ParisTech-UPMC, PSL University, 10 rue Vauquelin, 75005 Paris, France
| | - Jaume Gázquez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - María Varela
- 1] Materials Science &Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA [2] GFMC, Department de Fisica Aplicada III &Instituto Pluridisciplinar, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Mateusz Scigaj
- 1] Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain [2] Departament de Física, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Barcelona, Catalonia, Spain
| | - Nico Dix
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Florencio Sánchez
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
| | - Josep Fontcuberta
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Catalonia, Spain
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