Impurity suppression of the critical temperature in the iron-based superconductors

TL;DR

This paper theoretically investigates how impurities affect the critical temperature in iron-based superconductors, revealing that both magnetic and non-magnetic impurities suppress $T_c$ similarly to d-wave superconductors.

Contribution

It introduces a comprehensive $ ext{T}$-matrix approach to analyze impurity effects in $ ext{FeAs}$ superconductors with $ ext{±s}$-wave pairing, highlighting the impurity suppression mechanism.

Findings

Both magnetic and non-magnetic impurities suppress $T_c$ at similar rates.

Impurity effects are governed by the density of states and order parameter magnitude.

Suppression behavior resembles that of d-wave superconductors.

Abstract

We study the impurity suppression of the critical temperature $T_c$ of the FeAs superconductors theoretically based on the the $\pm$s-wave pairing state of a two band model. The effects of non-magnetic and magnetic impurities are studied with the $\mathcal{T}$-matrix approximation, which can continuously treat impurity scattering from weak to strong coupling limit. We found that both magnetic and non-magnetic impurities suppress $T_c$ with a rate that is practically indistinguishable from the standard d-wave case despite a possibly large difference of the positive and negative s-wave order parameter (OP) magnitudes. This is because the density of states enters together with the OP magnitude for the scattering process.