Broadening of Andreev-Bound States in d_{x^2-y^2} superconductors

TL;DR

This paper studies how impurities affect the broadening of Andreev-bound states in d_{x^2-y^2} superconductors, revealing that strong scatterers cause less broadening than weak scatterers and analyzing implications for Josephson currents.

Contribution

It provides a detailed analysis of impurity-induced broadening of bound states in unconventional superconductors using quasiclassical theory, comparing Born and unitarity limits.

Findings

Unitary scatterers cause less broadening than Born scatterers.

Impurity scattering influences the temperature dependence of Josephson critical current.

The study covers various geometries and impurity regimes.

Abstract

We investigate the broadening of the bound states at an interface of an unconventional superconductor by bulk impurity scattering. We use the quasiclassical theory and include impurity scattering in the Born and in the unitarity limit. The broadening of bound states due to unitary scatterers is shown to be substantially weaker than in the Born limit. We study various model geometries and calculate the temperature dependence of the Josephson critical current in the presence of these impurity-broadened bound states.