Non-magnetic impurities in two dimensional superconductors

TL;DR

This paper presents a numerical method for studying disordered 2D superconductors using BCS theory, focusing on impurity effects on properties like energy gap and superfluid density, with implications for experimental observations.

Contribution

It introduces a self-consistent numerical approach to model impurity effects in 2D superconductors, emphasizing the importance of impurity potential range.

Findings

Impurity potential range significantly affects superconducting properties.

The method reproduces results of analytic approaches where applicable.

Impurity effects can explain rapid suppression of superconductivity in experiments.

Abstract

A numerical approach to disordered 2D superconductors described by BCS mean field theory is outlined. The energy gap and the superfluid density at zero temperature and the quasiparticle density of states are studied. The method involves approximate self-consistent solutions of the Bogolubov-de$\,$Gennes equations on finite square lattices. Where comparison is possible, the results of standard analytic approaches to this problem are reproduced. Detailed modeling of impurity effects is practical using this approach. The {\it range} of the impurity potential is shown to be of {\it quantitative importance} in the case of strong potential scatterers. We discuss the implications for experiments, such as the rapid suppression of superconductivity by Zn doping in Copper-Oxide superconductors.