Quasiparticle States near the Surface and the Domain Wall in a p_x\pm i p_y-Wave Superconductor

TL;DR

This paper investigates the electronic states near surfaces and domain walls in a p_x ± i p_y-wave superconductor, revealing unique local density of states features and effects of magnetic fields, relevant to Sr_2 Ru O_4.

Contribution

It provides a self-consistent analysis of quasiparticle states in a chiral p-wave superconductor, highlighting differences from d-wave superconductors and effects at domain walls.

Findings

Local density of states at the surface is constant with no peaks.

External magnetic fields mainly affect energies above the bulk gap.

A small energy gap exists at the domain wall between degenerate states.

Abstract

The electronic states near a surface or a domain wall in the p-wave superconductor are studied for the order parameter of the form p_x\pm i p_y-wave, which is a unitary odd-parity state with broken time-reversal symmetry. This state has been recently suggested as the superconducting state of Sr_2 Ru O_4. The spatial variation of the order parameter and vector potential is determined self-consistently within the quasi-classical approximation. The local density of states at the surface is constant and does not show any peak-like or gap-like structure within the superconducting energy gap, in contrast to the case of the d-wave superconductors. The influence of an external magnetic field is mainly observable in the energy range above the bulk gap. On the other hand, there is a small energy gap in the local density of states at the domain wall between domains of the two degenerate p_x+i p_y-wave and p_x-i p_y-wave states.