Cooper pairing in the insulating valence band in iron-based superconductors

Lun-Hui Hu; Wei-Qiang Chen; Fu-Chun Zhang

doi:10.1103/PhysRevB.91.161108

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Cooper pairing in the insulating valence band in iron-based superconductors

Lun-Hui Hu, Wei-Qiang Chen, Fu-Chun Zhang

DOI 10.1103/PhysRevB.91.161108 · Physical Review B

T1

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Abstract

Conventional Cooper pairing arises from attractive interaction of electrons in the metallic bands. A 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.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
LiFe1-xCoxAs Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
LiFeAs Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown