Weak anisotropic impurity scattering in unconventional superconductors

TL;DR

This paper investigates how weak anisotropic impurity scattering affects unconventional superconductors, revealing that it can either slightly suppress or enhance superconductivity, with significant effects for certain order parameters.

Contribution

It demonstrates that anisotropic impurity scattering can unexpectedly increase the critical temperature in unconventional superconductors at low impurity levels.

Findings

Anisotropic scattering can enhance the critical temperature by up to 10%.

The effect is significant for order parameters with large Fermi surface averages.

Weak anisotropic impurity scattering can either reduce or enhance superconductivity.

Abstract

The effect of weak anisotropic (momentum-dependent) impurity scattering in unconventional superconductors has been investigated. It is shown that the anisotropic scattering can lead either to a small reduction or a small enhancement of the isotropic pair-breaking effect. The influence of the anisotropy of the scattering potential becomes significant for the order parameters with large Fermi surface average values. In that case an unexpected enhancement (up to 10%) of the critical temperature over the critical temperature in the absence of impurities is predicted for a small impurity concentration.