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On the electron pairing mechanism of copper-oxide high temperature superconductivity. Proc Natl Acad Sci U S A 2022; 119:e2207449119. [PMID: 36067325 PMCID: PMC9477408 DOI: 10.1073/pnas.2207449119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The elementary CuO2 plane sustaining cuprate high-temperature superconductivity occurs typically at the base of a periodic array of edge-sharing CuO5 pyramids. Virtual transitions of electrons between adjacent planar Cu and O atoms, occurring at a rate t/ℏ and across the charge-transfer energy gap [Formula: see text], generate "superexchange" spin-spin interactions of energy [Formula: see text] in an antiferromagnetic correlated-insulator state. However, hole doping this CuO2 plane converts this into a very-high-temperature superconducting state whose electron pairing is exceptional. A leading proposal for the mechanism of this intense electron pairing is that, while hole doping destroys magnetic order, it preserves pair-forming superexchange interactions governed by the charge-transfer energy scale [Formula: see text]. To explore this hypothesis directly at atomic scale, we combine single-electron and electron-pair (Josephson) scanning tunneling microscopy to visualize the interplay of [Formula: see text] and the electron-pair density nP in Bi2Sr2CaCu2O8+x. The responses of both [Formula: see text] and nP to alterations in the distance δ between planar Cu and apical O atoms are then determined. These data reveal the empirical crux of strongly correlated superconductivity in CuO2, the response of the electron-pair condensate to varying the charge-transfer energy. Concurrence of predictions from strong-correlation theory for hole-doped charge-transfer insulators with these observations indicates that charge-transfer superexchange is the electron-pairing mechanism of superconductive Bi2Sr2CaCu2O8+x.
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Abstract
We discuss a few possibilities of high- T c superconductivity with more than one orbital symmetry contributing to the pairing. First, we show that the high energies of orbital excitations in various cuprates suggest a simplified model with a single orbital of x 2 − y 2 symmetry doped by holes. Next, several routes towards involving both e g orbital symmetries for doped holes are discussed: (i) some give superconductivity in a CuO 2 monolayer on Bi2212 superconductors, Sr 2 CuO 4 − δ , Ba 2 CuO 4 − δ , while (ii) others as nickelate heterostructures or Eu 2 − x Sr x NiO 4 , could in principle realize it as well. At low electron filling of Ru ions, spin-orbital entangled states of t 2 g symmetry contribute in Sr 2 RuO 4 . Finally, electrons with both t 2 g and e g orbital symmetries contribute to the superconducting properties and nematicity of Fe-based superconductors, pnictides or FeSe. Some of them provide examples of orbital-selective Cooper pairing.
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Jiang K, Wu X, Hu J, Wang Z. Nodeless High-T_{c} Superconductivity in the Highly Overdoped CuO_{2} Monolayer. PHYSICAL REVIEW LETTERS 2018; 121:227002. [PMID: 30547640 DOI: 10.1103/physrevlett.121.227002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Indexed: 06/09/2023]
Abstract
We study the electronic structure and superconductivity in a CuO_{2} monolayer grown recently on the d-wave cuprate superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Density functional theory calculations indicate a significant charge transfer across the interface such that the CuO_{2} monolayer is heavily overdoped into the hole-rich regime yet inaccessible in bulk cuprates. We show that both the Cu d_{x^{2}-y^{2}} and d_{3z^{2}-r^{2}} orbitals become important and the Fermi surface contains one electron and one hole pocket associated with the two orbitals, respectively. Constructing a minimal correlated two-orbital model for the e_{g} complex, we show that the spin-orbital exchange interactions produce a nodeless superconductor with extended s-wave pairing symmetry and a pairing energy gap comparable to the bulk d-wave gap, in agreement with recent experiments. The findings point to a direction of realizing new high-T_{c} superconductors in ozone grown transition-metal-oxide monolayer heterostructures.
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Affiliation(s)
- Kun Jiang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xianxin Wu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Institut für Theoretische Physik und Astrophysik, Julius-Maximilians-Universität Würzburg, 97074 Würzburg, Germany
| | - Jiangping Hu
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- Kavli Institute of Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Ziqiang Wang
- Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467, USA
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Komori S, Di Bernardo A, Buzdin AI, Blamire MG, Robinson JWA. Magnetic Exchange Fields and Domain Wall Superconductivity at an All-Oxide Superconductor-Ferromagnet Insulator Interface. PHYSICAL REVIEW LETTERS 2018; 121:077003. [PMID: 30169105 DOI: 10.1103/physrevlett.121.077003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/20/2018] [Indexed: 06/08/2023]
Abstract
At a superconductor-ferromagnet (S/F) interface, the F layer can introduce a magnetic exchange field within the S layer, which acts to locally spin split the superconducting density of states. The effect of magnetic exchange fields on superconductivity has been thoroughly explored at S-ferromagnet insulator (S/FI) interfaces for isotropic s-wave S and a thickness that is smaller than the superconducting coherence length. Here we report a magnetic exchange field effect at an all-oxide S/FI interface involving the anisotropic d-wave high temperature superconductor praseodymium cerium copper oxide (PCCO) and the FI praseodymium calcium manganese oxide (PCMO). The magnetic exchange field in PCCO, detected via magnetotransport measurements through the superconducting transition, is localized to the PCCO/PCMO interface with an average magnitude that depends on the presence or absence of magnetic domain walls in PCMO. The results are promising for the development of all-oxide superconducting spintronic devices involving unconventional pairing and high temperature superconductors.
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Affiliation(s)
- S Komori
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - A Di Bernardo
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - A I Buzdin
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- University Bordeaux, LOMA UMR-CNRS 5798, F-33405 Talence Cedex, France
| | - M G Blamire
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
| | - J W A Robinson
- Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
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Disa AS, Kumah DP, Malashevich A, Chen H, Arena DA, Specht ED, Ismail-Beigi S, Walker FJ, Ahn CH. Orbital engineering in symmetry-breaking polar heterostructures. PHYSICAL REVIEW LETTERS 2015; 114:026801. [PMID: 25635555 DOI: 10.1103/physrevlett.114.026801] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Indexed: 05/21/2023]
Abstract
We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO_{3}-LaNiO_{3}-LaAlO_{3} system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ∼50% change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO_{3} and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.
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Affiliation(s)
- Ankit S Disa
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Divine P Kumah
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Andrei Malashevich
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Hanghui Chen
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Department of Physics, Columbia University, New York, New York 10027, USA and Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
| | - Dario A Arena
- National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Eliot D Specht
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Sohrab Ismail-Beigi
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Departments of Physics and Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
| | - F J Walker
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA
| | - Charles H Ahn
- Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06511, USA and Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA and Departments of Physics and Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA
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Pereiro J, Bollinger AT, Logvenov G, Gozar A, Panagopoulos C, Bozović I. Insights from the study of high-temperature interface superconductivity. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2012; 370:4890-4903. [PMID: 22987034 DOI: 10.1098/rsta.2012.0219] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A brief overview is given of the studies of high-temperature interface superconductivity based on atomic-layer-by-layer molecular beam epitaxy (ALL-MBE). A number of difficult materials science and physics questions have been tackled, frequently at the expense of some technical tour de force, and sometimes even by introducing new techniques. ALL-MBE is especially suitable to address questions related to surface and interface physics. Using this technique, it has been demonstrated that high-temperature superconductivity can occur in a single copper oxide layer-the thinnest superconductor known. It has been shown that interface superconductivity in cuprates is a genuine electronic effect-it arises from charge transfer (electron depletion and accumulation) across the interface driven by the difference in chemical potentials rather than from cation diffusion and mixing. We have also understood the nature of the superconductor-insulator phase transition as a function of doping. However, a few important questions, such as the mechanism of interfacial enhancement of the critical temperature, are still outstanding.
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Affiliation(s)
- J Pereiro
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore, Republic of Singapore
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Chen CC, Moritz B, Vernay F, Hancock JN, Johnston S, Jia CJ, Chabot-Couture G, Greven M, Elfimov I, Sawatzky GA, Devereaux TP. Unraveling the nature of charge excitations in La₂CuO₄ with momentum-resolved Cu K-edge resonant inelastic x-ray scattering. PHYSICAL REVIEW LETTERS 2010; 105:177401. [PMID: 21231077 DOI: 10.1103/physrevlett.105.177401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Indexed: 05/30/2023]
Abstract
The results of model calculations using exact diagonalization reveal the orbital character of states associated with different Raman loss peaks in Cu K-edge resonant inelastic x-ray scattering (RIXS) from La₂CuO₄. The model includes electronic orbitals necessary to highlight the nonlocal Zhang-Rice singlet, charge transfer, and d-d excitations, as well as states with apical oxygen 2p(z) character. The dispersion of these excitations is discussed with prospects for resonant final state wave-function mapping. A good agreement with experiments emphasizes the substantial multiorbital character of RIXS profiles in the energy transfer range 1-6 eV.
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Affiliation(s)
- C-C Chen
- Stanford Institute for Materials and Energy Science, Menlo Park, California 94025, USA
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Anomalous expansion of the copper-apical-oxygen distance in superconducting cuprate bilayers. Proc Natl Acad Sci U S A 2010; 107:8103-7. [PMID: 20404212 DOI: 10.1073/pnas.0914702107] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have introduced an improved x-ray phase-retrieval method with unprecedented speed of convergence and precision, and used it to determine with sub-Angstrom resolution the complete atomic structure of epitaxial La(2-x)Sr(x)CuO(4) ultrathin films. We focus on superconducting heterostructures built from constituent materials that are not superconducting in bulk samples. Single-phase metallic or superconducting films are also studied for comparison. The results show that this phase-retrieval diffraction method enables accurate measurement of structural modifications in near-surface layers, which may be critically important for elucidation of surface-sensitive experiments. Specifically we find that, while the copper-apical-oxygen distance remains approximately constant in single-phase films, it shows a dramatic increase from the metallic-insulating interface of the bilayer towards the surface by as much as 0.45 A. The apical-oxygen displacement is known to have a profound effect on the superconducting transition temperature.
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Srivastava P, Studer F, Garg KB, Gasser C, Murray H, Pompa M. Role of out-of-plane copper orbitals in thallium cuprate. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:693-699. [PMID: 9984306 DOI: 10.1103/physrevb.54.693] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Feiner LF, Jefferson JH, Raimondi R. Intrasublattice Hopping in the Extended t-J Model and Tmaxc in the Cuprates. PHYSICAL REVIEW LETTERS 1996; 76:4939-4942. [PMID: 10061418 DOI: 10.1103/physrevlett.76.4939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Raimondi R, Jefferson JH, Feiner LF. Effective single-band models for the high-Tc cuprates. II. Role of apical oxygen. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:8774-8788. [PMID: 9982390 DOI: 10.1103/physrevb.53.8774] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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12
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Bucci F, Castellani C, Grilli M. Charge fluctuations in the four-band extended Hubbard model. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:6880-6893. [PMID: 9981918 DOI: 10.1103/physrevb.52.6880] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Caprara S, Grilli M. Three-band t-J model: A systematic large-N analysis. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:6971-6984. [PMID: 10009425 DOI: 10.1103/physrevb.49.6971] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Vanderah TA, Lowe-Ma CK. Crystal-chemical anomalies in nonsuperconducting PrBa2Cu3O7. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00730378] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Schleger P, Hardy WN, Casalta H. Model for the high-temperature oxygen-ordering thermodynamics in YBa2Cu3O6+x: Inclusion of electron spin and charge degrees of freedom. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:514-523. [PMID: 10009312 DOI: 10.1103/physrevb.49.514] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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16
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Pellegrin E, Nücker N, Fink J, Simmons CT, Kaindl G, Bernhard J, Renk KF, Kumm G, Winzer K. Polarized x-ray-absorption study of Tl2Ba2CaCu2O8 and Tl2Ba2Ca2Cu3O10. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:10520-10523. [PMID: 10007330 DOI: 10.1103/physrevb.48.10520] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Yonemitsu K, Bishop AR, Lorenzana J. Doping states in the two-dimensional three-band Peierls-Hubbard model. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 47:12059-12088. [PMID: 10005378 DOI: 10.1103/physrevb.47.12059] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Welp U, Grimsditch M, Fleshler S, Nessler W, Downey J, Crabtree GW, Guimpel J. Effect of uniaxial stress on the superconducting transition in YBa2Cu3O7. PHYSICAL REVIEW LETTERS 1992; 69:2130-2133. [PMID: 10046406 DOI: 10.1103/physrevlett.69.2130] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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