Bypassing the lattice BCS-BEC crossover in strongly correlated superconductors: resilient coherence from multiorbital physics

Fuente: arXiv
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Auteurs principaux: Witt, Niklas, Nomura, Yusuke, Brener, Sergey, Arita, Ryotaro, Lichtenstein, Alexander I., Wehling, Tim O.
Format: Preprint
Publié: 2023
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author Witt, Niklas
Nomura, Yusuke
Brener, Sergey
Arita, Ryotaro
Lichtenstein, Alexander I.
Wehling, Tim O.
author_facet Witt, Niklas
Nomura, Yusuke
Brener, Sergey
Arita, Ryotaro
Lichtenstein, Alexander I.
Wehling, Tim O.
contents 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 (A$_3$C$_{60}$) 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 ($λ_{\mathrm{L}}$), even in presence of strong electron correlations.
format Preprint
id arxiv_https___arxiv_org_abs_2310_09063
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Bypassing the lattice BCS-BEC crossover in strongly correlated superconductors: resilient coherence from multiorbital physics
Witt, Niklas
Nomura, Yusuke
Brener, Sergey
Arita, Ryotaro
Lichtenstein, Alexander I.
Wehling, Tim O.
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Superconductivity
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 (A$_3$C$_{60}$) 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 ($λ_{\mathrm{L}}$), even in presence of strong electron correlations.
title Bypassing the lattice BCS-BEC crossover in strongly correlated superconductors: resilient coherence from multiorbital physics
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
Superconductivity
url https://arxiv.org/abs/2310.09063