Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics

Abstract Superconductivity emerges from the spatial coherence of a macroscopic condensate of Cooper pairs. Increasingly strong binding and localization of electrons into these pairs compromises the condensate’s phase stiffness, thereby limiting critical temperatures – a phenomenon known as the BCS–B...

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Main Authors: Niklas Witt, Yusuke Nomura, Sergey Brener, Ryotaro Arita, Alexander I. Lichtenstein, Tim O. Wehling
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:npj Quantum Materials
Online Access:https://doi.org/10.1038/s41535-024-00706-7
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author Niklas Witt
Yusuke Nomura
Sergey Brener
Ryotaro Arita
Alexander I. Lichtenstein
Tim O. Wehling
author_facet Niklas Witt
Yusuke Nomura
Sergey Brener
Ryotaro Arita
Alexander I. Lichtenstein
Tim O. Wehling
author_sort Niklas Witt
collection DOAJ
description Abstract Superconductivity emerges from the spatial coherence of a macroscopic condensate of Cooper pairs. Increasingly strong binding and localization of electrons into these pairs compromises the condensate’s phase stiffness, thereby limiting critical temperatures – a phenomenon known as the BCS–BEC crossover in lattice systems. In this study, we demonstrate enhanced superconductivity in a multiorbital model of alkali-doped fullerides (A3C60) that goes beyond the limits of the lattice BCS–BEC crossover. We identify that the interplay of strong correlations and multiorbital effects results in a localized superconducting state characterized by a short coherence length but robust stiffness and a domeless rise in critical temperature with increasing pairing interaction. To derive these insights, we introduce a new theoretical framework allowing us to calculate the fundamental length scales of superconductors, namely the coherence length (ξ 0) and the London penetration depth (λ L), even in presence of strong electron correlations.
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spelling doaj-art-78771ec7fbd84ebe9cb6fe9cfda352a72024-12-15T12:06:04ZengNature Portfolionpj Quantum Materials2397-46482024-12-019111010.1038/s41535-024-00706-7Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physicsNiklas Witt0Yusuke Nomura1Sergey Brener2Ryotaro Arita3Alexander I. Lichtenstein4Tim O. Wehling5I. Institute of Theoretical Physics, University of HamburgInstitute for Materials Research (IMR), Tohoku UniversityI. Institute of Theoretical Physics, University of HamburgDepartment of Physics, The University of TokyoI. Institute of Theoretical Physics, University of HamburgI. Institute of Theoretical Physics, University of HamburgAbstract Superconductivity emerges from the spatial coherence of a macroscopic condensate of Cooper pairs. Increasingly strong binding and localization of electrons into these pairs compromises the condensate’s phase stiffness, thereby limiting critical temperatures – a phenomenon known as the BCS–BEC crossover in lattice systems. In this study, we demonstrate enhanced superconductivity in a multiorbital model of alkali-doped fullerides (A3C60) that goes beyond the limits of the lattice BCS–BEC crossover. We identify that the interplay of strong correlations and multiorbital effects results in a localized superconducting state characterized by a short coherence length but robust stiffness and a domeless rise in critical temperature with increasing pairing interaction. To derive these insights, we introduce a new theoretical framework allowing us to calculate the fundamental length scales of superconductors, namely the coherence length (ξ 0) and the London penetration depth (λ L), even in presence of strong electron correlations.https://doi.org/10.1038/s41535-024-00706-7
spellingShingle Niklas Witt
Yusuke Nomura
Sergey Brener
Ryotaro Arita
Alexander I. Lichtenstein
Tim O. Wehling
Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
npj Quantum Materials
title Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
title_full Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
title_fullStr Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
title_full_unstemmed Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
title_short Bypassing the lattice BCS–BEC crossover in strongly correlated superconductors through multiorbital physics
title_sort bypassing the lattice bcs bec crossover in strongly correlated superconductors through multiorbital physics
url https://doi.org/10.1038/s41535-024-00706-7
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