Transport Properties of "Extended-s" State Superconductors

TL;DR

This paper investigates the transport properties of extended s-wave superconductors, highlighting how impurity effects influence residual conductivities and how transport measurements can distinguish them from d-wave states.

Contribution

It provides a detailed analysis of impurity effects on transport in extended s-wave superconductors, offering a method to differentiate them from d-wave states experimentally.

Findings

Residual conductivities are large and inversely proportional to impurity concentration.

Transport measurements can distinguish extended s-wave from d-wave superconductors.

Impurity effects on thermodynamic properties reflect a residual density of states.

Abstract

Superconducting states with "extended s-wave" symmetry have been suggested in connection with recent ARPES experiments on BSCCO. In the presence of impurities, thermodynamic properties of such states reflect a residual density of states $N(0)$ for a range of concentrations. While properties reflecting $N(\omega)$ alone will be similar to those of d-wave states, transport measurements may be shown to qualitatively distinguish between the two. In contrast to the d-wave case with unitarity limit scattering, limiting low-temperature residual conductivities in the s-wave state are large and scale inversely with impurity concentration.