Funtional Renormalization Group Study of the Pairing Symmetry and Pairing Mechanism of the FeAs Based High Temperature Superconductors

TL;DR

This study uses the functional renormalization group method to analyze the pairing symmetry and mechanism in FeAs-based high-temperature superconductors, revealing an extended s-wave pairing driven by antiferromagnetic correlations.

Contribution

It is the first to apply the fermion functional renormalization group to determine pairing symmetry and mechanism in FeAs superconductors with a five-band model.

Findings

Extended s-wave pairing is most favorable.

Pairing mechanism is driven by inter Fermi surface Josephson scattering.

Superconductivity is electronic-driven with repulsive interactions.

Abstract

We apply the fermion functional renormalization group method to determine the pairing symmetry and pairing mechanism of the FeAs-Based materials. Within a five band model with pure repulsive interactions, we find an electronic-driven superconducting pairing instability. For the doping and interaction parameters we have examined, extended s-wave, whose order parameter takes on opposite sign on the electron and hole pockets, is always the most favorable pairing symmetry. The pairing mechanism is the inter Fermi surface Josephson scattering generated by the antiferromagnetic correlation.