Influence of impurity-scattering on tunneling conductance in d-wave superconductors with broken time reversal symmetry

TL;DR

This study investigates how impurity scattering affects tunneling conductance in d-wave superconductors with broken time-reversal symmetry, revealing suppression and splitting of conductance peaks depending on impurity levels.

Contribution

It provides a detailed analysis of impurity effects on tunneling conductance in unconventional superconductors with broken time-reversal symmetry using advanced theoretical methods.

Findings

Impurity scattering suppresses the zero-bias conductance peak amplitude.

In d+is-wave superconductors, impurity scattering causes the ZBCP to split into two peaks.

The splitting peaks' positions remain stable despite strong impurity scattering.

Abstract

Effects of impurity scattering on tunneling conductance in dirty normal-metal/insulator/superconductor junctions are studied based on the Kubo formula and the recursive Green function method. The zero-bias conductance peak (ZBCP) is a consequence of the unconventional pairing symmetry in superconductors. The impurity scattering in normal metals suppresses the amplitude of the ZBCP. The degree of the suppression agrees well with results of the quasiclassical Green function theory. When superconductors have $d$+is-wave pairing symmetry, the time-reversal symmetry is broken in superconductors and the ZBCP splits into two peaks. The random impurity scattering reduces the height of the two splitting peaks. The position of the splitting peaks, however, almost remains unchanged even in the presence of the strong impurity scattering. Thus the two splitting peaks never merge into a single ZBCP.