Singular current response from isolated impurities in d-wave superconductors

TL;DR

This paper calculates the current response of a d-wave superconductor with a single impurity, revealing a singular low-temperature behavior that could be observed in cuprate superconductors.

Contribution

It introduces a theoretical analysis of impurity effects on current response in d-wave superconductors, highlighting a singular low-temperature response similar to surface bound states.

Findings

Singular current response at low temperatures due to impurities

1/T term in penetration depth for strong scattering

Potential observability of effects in cuprate superconductors

Abstract

The current response of a d-wave superconductor containing a single impurity is calculated and shown to be singular in the low-temperature limit, leading in the case of strong scattering to a 1/T term in the penetration depth $\lambda(T)$ similar to that induced by Andreev surface bound states. For a small number of such impurities, we argue this low-$T$ upturn could be observable in cuprate superconductors.