Cooper Pairing in Insulating Valence Band in Fe-Based Superconductors

Abstract

Conventional Cooper pairing arises from attractive interaction of electrons in the metallic bands. Recent experiment on Co-doped LiFeAs shows superconductivity in the insulating valence band, which is evolved from a metallic hole band upon doping. Here we examine this phenomenon by studying superconductivity in a three-orbital Hamiltonian relevant to the doped LiFeAs. We show explicitly that Cooper pairing of the insulating hole band requires a finite pairing interaction strength. For strong coupling, the superconductivity in the hole band is robust against the sink of the hole band below the Fermi level. Our theory predicts a substantial upward shift of the chemical potential in the superconducting transition for Co-doped LiFeAs.

5 pages, 5 figures

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Cited by in corpus (3)

• Theory of superconductivity with non-Hermitian and parity-time reversal symmetric cooper pairing symmetry
• Strong Correlations, Strong Coupling and s-wave Superconductivity in Hole-doped BaFe2As2 Single Crystals
• Superconductivity in the bilayer Hubbard model: Are two Fermi surfaces better than one?