Anomalous surface states at interfaces in p-wave superconductors

TL;DR

This paper theoretically investigates surface states in two-dimensional p-wave superconductors, revealing the robustness of zero-energy peaks in certain states and complex spectral features influenced by surface roughness.

Contribution

It develops a self-consistent approach for analyzing surface states in p-wave superconductors with rough interfaces, highlighting the stability of odd-frequency pairing and spectral modifications.

Findings

Zero-energy peak in p_x state remains robust against surface roughness.

Surface roughness induces multi-peak subgap structures in chiral p_x + i p_y states.

Odd-frequency pairing states are stable at the surface despite disorder.

Abstract

We present the results of theoretical study of surface state properties in a two-dimensional model for triplet $p$-wave superconductors. We derive boundary conditions for Eilenberger equations at rough interfaces and develop the approach for self-consistent solution for the spatial dependence of $p_{x}$ and $p_{x}+i~p_{y}$ -wave pair potentials. In the $p_{x}$ case we demonstrate the robustness of the zero-energy peak in the density of states (DoS) with respect to surface roughness, in contrast to the suppression of such a peak in the case of $d_{xy}$ symmetry. This effect is due to stability of odd-frequency pairing state at the surface with respect to disorder. In the case of the chiral $p_{x}+i~p_{y}$ state we demonstrate the appearance of a complex multi-peak subgap structure in the spectrum with increasing surface roughness.