Pairing mechanism in Fe-based superconductors

TL;DR

This paper reviews the symmetry, structure, and universal pairing mechanism of superconductivity in Fe-based superconductors, emphasizing that diverse pairing states can be explained by a single effective low-energy model.

Contribution

It demonstrates that all observed pairing states in Fe-based superconductors can be understood through a universal pairing scenario within a simplified effective model.

Findings

Superconducting gap symmetry varies with composition.

A universal pairing mechanism explains diverse pairing states.

Effective low-energy models with few parameters suffice.

Abstract

I review recent works on the symmetry and the structure of the superconducting gap in Fe-based superconductors and on the underlying pairing mechanism in these systems. The experimental data on superconductivity show very rich behavior, with potentially different symmetry of a superconducting state for different compositions of the same material. The variety of different pairing states raised the issue whether the physics of Fe-based superconductors is model-dependent or is universal, governed by a single underlying pairing mechanism. I argue that the physics is universal and that all pairing states obtained so far can be understood within the same universal pairing scenario and are well described by the effective low-energy model with a small number of input parameters.