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Condensed Matter > Strongly Correlated Electrons
Title: Bypassing the lattice BCS-BEC crossover in strongly correlated superconductors: resilient coherence from multiorbital physics
(Submitted on 13 Oct 2023 (v1), last revised 4 Apr 2024 (this version, v2))
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 report on an enhancement of superconductivity beyond the limits of the lattice BCS-BEC crossover realized in a multiorbital model of alkali-doped fullerides (A$_3$C$_{60}$). We show how strong correlations and multiorbital effects lead into a localized superconducting regime characterized by a short coherence length but robust stiffness and a domeless rise in critical temperature with increasing pairing interaction. These insights are derived from the development of a theoretical framework to calculate the fundamental length scales of superconductors, namely the coherence length ($\xi_0$) and the London penetration depth ($\lambda_{\mathrm{L}}$), in microscopic theories and from first principles, even in presence of strong electron correlations.
Submission history
From: Niklas Witt [view email][v1] Fri, 13 Oct 2023 12:38:39 GMT (3758kb,D)
[v2] Thu, 4 Apr 2024 15:10:32 GMT (4667kb,D)
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