Quasiparticles near domain walls in hexagonal superconductors

TL;DR

This paper investigates quasiparticle energy spectra near domain walls in hexagonal superconductors, revealing how their features depend on symmetry, orientation, and phase differences, aiding in identifying pairing symmetries.

Contribution

It provides a detailed calculation of quasiparticle bound states near domain walls in hexagonal superconductors, linking spectral features to pairing symmetries and domain orientations.

Findings

Quasiparticle bound state energies depend on gap symmetry and domain wall orientation.

Density of states shows a zero-energy singularity that indicates pairing symmetry.

Features in the density of states can be used to distinguish different superconducting states.

Abstract

We calculate the energy spectrum of quasiparticles trapped by a domain wall separating different time reversal symmetry-breaking ground states in a hexagonal superconductor, such as UPt$_3$. The bound state energy is found to be strongly dependent on the gap symmetry, the domain wall orientation, the quasiparticle's direction of semiclassical propagation, and the phase difference between the domains. We calculate the corresponding density of states and show how one can use its prominent features, in particular, the zero-energy singularity, to distinguish between different pairing symmetries.