Pairing in the iron arsenides: a functional RG treatment

TL;DR

This paper uses a functional renormalization group approach to analyze the phase diagram of iron arsenides, revealing dominant extended s-wave pairing and the importance of electron-hole pocket scattering.

Contribution

It connects simplified two-patch models with detailed five-band analyses, providing new insights into pairing mechanisms and phase transitions in iron arsenides.

Findings

Extended s-wave pairing dominates over a wide parameter range.

Electron-hole pocket scattering is crucial for pairing.

Phase transition between antiferromagnetic and superconducting phases may be first order.

Abstract

We study the phase diagram of a microscopic model for the superconducting iron arsenides by means of a functional renormalization group. Our treatment establishes a connection between a strongly simplified two-patch model by Chubukov et al. and a five-band- analysis by Wang et al.. For a wide parameter range, the dominant pairing instability occurs in the extended s-wave channel. The results clearly show the relevance of pair scattering between electron and hole pockets. We also give arguments that the phase transition between the antiferromagnetic phase for the undoped system and the superconducting phase may be first order.