Unconventional superconductivity with preformed pairs in twisted bilayer graphene

We present a theory of superconductivity in magic-angle twisted bilayer graphene and analyze the superconducting phase diagram in presence of the magnetic field. Namely, we consider a model of a granular array hosting localized states, which are hybridized via the delocalized fermions in the inter-g...

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Bibliographic Details
Published in:arXiv.org 2022-08
Main Authors: SK Firoz Islam, A Yu Zyuzin, Zyuzin, Alexander A
Format: Article
Language:English
Subjects:
Bilayers
Coherent scattering
Cooper pairs
Coupling
Fermions
Graphene
Magnetic fields
Phase diagrams
Phase transitions
Superconductivity
Unconventional superconductivity
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Summary:We present a theory of superconductivity in magic-angle twisted bilayer graphene and analyze the superconducting phase diagram in presence of the magnetic field. Namely, we consider a model of a granular array hosting localized states, which are hybridized via the delocalized fermions in the inter-grain regions. We study a strong coupling situation when the interactions lead to an incoherent state with preformed Cooper pairs inside the grains. The Andreev scattering among different grains manifests itself through the global phase-coherent superconducting state at lower temperatures. We demonstrate that a new phase transition between the preformed Cooper pairing state and the Larkin-Ovchinnikov-Fulde-Ferrell state might be induced by the spin pair-breaking effect of in-plane magnetic field. The upper critical magnetic field is shown to be enhanced in the strong coupling case.
ISSN:2331-8422
DOI:10.48550/arxiv.2208.12039