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Al-Tawhid AH, Poage SJ, Salmani-Rezaie S, Gonzalez A, Chikara S, Muller DA, Kumah DP, Gastiasoro MN, Lorenzana J, Ahadi K. Enhanced Critical Field of Superconductivity at an Oxide Interface. NANO LETTERS 2023; 23:6944-6950. [PMID: 37498750 DOI: 10.1021/acs.nanolett.3c01571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The nature of superconductivity and its interplay with strong spin-orbit coupling at the KTaO3(111) interfaces remain a subject of debate. To address this problem, we grew epitaxial LaMnO3/KTaO3(111) heterostructures. We show that superconductivity is robust against the in-plane magnetic field, with the critical field of superconductivity reaching ∼25 T in optimally doped heterostructures. The superconducting order parameter is highly sensitive to the carrier density. We argue that spin-orbit coupling drives the formation of anomalous quasiparticles with vanishing magnetic moment, providing significant condensate immunity against magnetic fields beyond the Pauli paramagnetic limit. These results offer design opportunities for superconductors with extreme resilience against the applied magnetic fields.
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Affiliation(s)
- Athby H Al-Tawhid
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27265, United States
| | - Samuel J Poage
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27265, United States
| | - Salva Salmani-Rezaie
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Antonio Gonzalez
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27265, United States
| | - Shalinee Chikara
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
| | - David A Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, United States
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, New York 14853, United States
| | - Divine P Kumah
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Maria N Gastiasoro
- Donostia International Physics Center, 20018 Donostia-San Sebastian, Spain
| | - José Lorenzana
- ISC-CNR and Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy
| | - Kaveh Ahadi
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27265, United States
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, United States
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Arnault EG, Al-Tawhid AH, Salmani-Rezaie S, Muller DA, Kumah DP, Bahramy MS, Finkelstein G, Ahadi K. Anisotropic superconductivity at KTaO 3(111) interfaces. SCIENCE ADVANCES 2023; 9:eadf1414. [PMID: 36791191 PMCID: PMC9931206 DOI: 10.1126/sciadv.adf1414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
A two-dimensional, anisotropic superconductivity was recently found at the KTaO3(111) interfaces. The nature of the anisotropic superconducting transition remains a subject of debate. To investigate the origins of the observed behavior, we grew epitaxial KTaO3(111)-based heterostructures. We show that the superconductivity is robust against the in-plane magnetic field and violates the Pauli limit. We also show that the Cooper pairs are more resilient when the bias is along [11[Formula: see text]] (I ∥ [11[Formula: see text]]) and the magnetic field is along [1[Formula: see text]0] (B ∥ [1[Formula: see text]0]). We discuss the anisotropic nature of superconductivity in the context of electronic structure, orbital character, and spin texture at the KTaO3(111) interfaces. The results point to future opportunities to enhance superconducting transition temperatures and critical fields in crystalline, two-dimensional superconductors with strong spin-orbit coupling.
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Affiliation(s)
| | - Athby H. Al-Tawhid
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27265, USA
| | - Salva Salmani-Rezaie
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
| | - David A. Muller
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853, USA
| | - Divine P. Kumah
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
| | - Mohammad S. Bahramy
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | | | - Kaveh Ahadi
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27265, USA
- Department of Physics, North Carolina State University, Raleigh, NC 27695, USA
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Zhou H, Holleis L, Saito Y, Cohen L, Huynh W, Patterson CL, Yang F, Taniguchi T, Watanabe K, Young AF. Isospin magnetism and spin-polarized superconductivity in Bernal bilayer graphene. Science 2022; 375:774-778. [PMID: 35025604 DOI: 10.1126/science.abm8386] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In conventional superconductors, Cooper pairing occurs between electrons of opposite spin. We observe spin-polarized superconductivity in Bernal bilayer graphene when doped to a saddle-point van Hove singularity generated by a large applied perpendicular electric field. We observe a cascade of electrostatic gate-tuned transitions between electronic phases distinguished by their polarization within the isospin space defined by the combination of the spin and momentum-space valley degrees of freedom. Although all of these phases are metallic at zero magnetic field, we observe a transition to a superconducting state at finite magnetic field B‖ ≈ 150 milliteslas applied parallel to the two-dimensional sheet. Superconductivity occurs near a symmetry-breaking transition and exists exclusively above the B‖ limit expected of a paramagnetic superconductor with the observed transition critical temperature TC ≈ 30 millikelvins, consistent with a spin-triplet order parameter.
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Affiliation(s)
- Haoxin Zhou
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Ludwig Holleis
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Yu Saito
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Liam Cohen
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - William Huynh
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Caitlin L Patterson
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Fangyuan Yang
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Andrea F Young
- Department of Physics, University of California at Santa Barbara, Santa Barbara, CA 93106, USA
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