Effects of momentum-dependent quasiparticle renormalization on the gap structure of iron-based superconductors

TL;DR

This paper investigates how momentum-dependent quasiparticle renormalization influences the superconducting gap structure in iron-based superconductors, extending spin-fluctuation pairing theory to better match experimental observations.

Contribution

It introduces a generalized weak-coupling framework incorporating quasiparticle renormalization effects to explain anisotropic gap structures.

Findings

Good agreement with experimental gap anisotropy in LiFeAs

Shows quasiparticle renormalization explains observed anomalies

Extends spin-fluctuation pairing theory to include anisotropic effects

Abstract

We discuss the influence of momentum-dependent correlations on the superconducting gap structure in iron-based superconductors. Within the weak coupling approach including self-energy effects at the one-loop spin-fluctuation level, we construct a dimensionless pairing strength functional which includes the effects of quasiparticle renormalization. The stationary solution of this equation determines the gap function at $T_c$. The resulting equations represent the simplest generalization of spin fluctuation pairing theory to include the effects of an anisotropic quasiparticle weight. We obtain good agreement with experimentally observed anisotropic gap structures in LiFeAs, indicating that the inclusion of quasiparticle renormalization effects in the existing weak-coupling theories can account for the observed anomalies in the gap structure of Fe-based superconductors.