Influence of the impurity scattering on charge transport in unconventional superconductor junctions

TL;DR

This paper investigates how non-magnetic impurity scatterings influence tunneling conductance in normal metal-unconventional superconductor junctions, revealing significant effects on Andreev bound states and spectra, aiding experimental pairing symmetry identification.

Contribution

It provides a self-consistent analysis of impurity effects on tunneling spectra in unconventional superconductor junctions, highlighting the role of odd-frequency Cooper pairs.

Findings

Impurity scattering modifies zero-bias tunneling spectra.

Formation of odd-frequency Cooper pairs near the interface.

Impurity effects depend on scattering strength and regime.

Abstract

We study the influence of non-magnetic impurity scatterings on the tunneling conductance of a junction consisting of a normal metal and a disordered unconventional superconductor by solving the quasiclassical Eilenberger equation self-consistently. We find that the impurity scatterings in both the Born and unitary limits affect the formation of the Andreev bound states and modify strongly the tunneling spectra around zero bias. Our results are interpreted well by the appearance of odd-frequency Cooper pairs near the interface and by the divergent behavior of the impurity self-energy. The present paper provides a useful tool to identify the pairing symmetry of unconventional superconductors in experiments.