Andreev Bound States, Surfaces and Subdominant Pairing in High Tc Superconductors

TL;DR

This paper investigates how particle-hole coherence affects surface phenomena in d-wave high-temperature superconductors, including bound states and symmetry breaking, using Fermi liquid theory.

Contribution

It provides a theoretical analysis of surface effects in high-Tc superconductors, incorporating surface roughness, and links particle-hole coherence to observable surface phenomena.

Findings

Surface bound states are influenced by surface roughness.

Particle-hole coherence leads to spontaneous time-reversal symmetry breaking.

Surface phenomena such as order parameter suppression are characterized.

Abstract

A characteristic feature of the BCS theory of superconductivity is the quantum-mechanical coherence of particle and hole states. Direct observation of particle-hole coherence in unusual superconducting materials is a strong indication of traditional superconductivity. We use the Fermi liquid theory of superconductivity to study the implications of particle-hole coherence on properties of d-wave superconductors near surfaces. Typical surface phenomena are the suppression of the superconducting order parameter, surface bound states associated with Andreev reflection, anomalous screening currents, and spontaneous breaking of time-reversal symmetry. We review these phenomena and present new results for the effects of surface roughness.