Uniform impurity scattering in two-band $s_\pm$ and $s_{++}$ superconductors

TL;DR

This paper investigates how uniform impurity scattering affects the critical temperature in two-band $s_ u$ superconductors, revealing a special case where disorder causes maximal damping of $T_c$ across various parameters.

Contribution

It identifies a unique impurity scattering scenario with equal intra- and interband potentials that maximally suppresses $T_c$ in $s_ u$ models.

Findings

Uniform impurity scattering leads to maximal $T_c$ damping at a specific parameter point.

The special case of equal intra- and interband potentials is isolated as a critical point.

Disorder effects vary significantly depending on impurity potential parameters.

Abstract

The $s_\pm$ and $s_{++}$ models for the superconducting state are subject of intense studies regarding Fe-based superconductors. Depending on the parameters, disorder may leave intact or suppress $T_c$ in these models. Here we study the special case of disorder with equal values of intra- and interband impurity potentials in the two-band $s_\pm$ and $s_{++}$ models. We show that this case can be considered as an isolated point and $T_c$ there has maximal damping for a wide range of parameters.