Edge-currents in superconductors with a broken time-reversal symmetry

TL;DR

This paper investigates edge currents and bands in a superconductor with broken time-reversal symmetry, revealing characteristic Friedel oscillations and edge-state features that serve as experimental fingerprints.

Contribution

It provides a detailed analysis of edge phenomena in a specific superconductor, combining self-consistent mean field and scattering theories to identify unique signatures.

Findings

Edge currents exhibit large Friedel oscillations with two distinct frequencies.

The shape of the edge-state band and the 2k_F frequency are unique to the d_{x^2-y^2}+id_{xy} superconductor.

The methods can be extended to study other time-reversal symmetry breaking superconductors.

Abstract

We analyze edge currents and edge bands at the surface of a time-reversal symmetry breaking d_{x^2-y^2}+id_{xy} superconductor. We show that the currents have large Friedel oscillations with two interfering frequencies: \sqrt{2}k_F from sub-gap states, and 2 k_F from the continuum. The results are based independently on a self-consistent slave-boson mean field theory for the t-J model on a triangular lattice, and on a T-matrix scattering theory calculation. The shape of the edge-state band, as well as the particular frequency \sqrt{2}k_F of the Friedel oscillations are attributes unique for the d_{x^2-y^2}+id_{xy} case, and may be used as a fingerprint for its identification. Extensions to different time-reversal symmetry breaking superconductors can be achieved within the same approach.