Split of zero-bias conductance peak in normal-metal / d-wave superconductor junctions

TL;DR

This paper demonstrates that impurity scattering near the interface in normal-metal/d-wave superconductor junctions can cause the splitting of the zero-bias conductance peak, challenging previous interpretations that linked it solely to broken time-reversal symmetry.

Contribution

It introduces a theoretical explanation for the split of the zero-bias conductance peak caused by impurity scattering, providing an alternative to the broken time-reversal symmetry hypothesis.

Findings

Impurity scattering near the interface causes zero-bias conductance peak splitting.

The theory explains experimental conductance spectra at finite temperatures and magnetic fields.

Challenges the previous belief that peak splitting indicates broken time-reversal symmetry.

Abstract

Effects of impurity scatterings on the conductance in normal-metal / $d$ wave superconductor junctions are discussed by using the single-site approximation. So far, the split of the zero-bias conductance peak has been believed to be an evidence of the broken time reversal symmetry states at the surface of high-$T_c$ superconductors. In this paper, however, it is shown that the impurity scattering near the interface also causes the split of the zero-bias conductance peak. Typical conductance spectra observed in experiments at finite temperatures and under external magnetic fields are explained well by the present theory.