Phase solitons and subgap excitations in two-band superconductors

TL;DR

This paper investigates phase solitons in two-band superconductors, revealing that they host bound subgap states and providing a comprehensive analysis of their energy spectrum across all temperatures.

Contribution

It introduces a detailed study of quasiparticle spectra and soliton energies in two-band superconductors, including exact analytical results for a simplified model.

Findings

Phase solitons host subgap bound states.

The soliton energy is calculated at all temperatures.

Analytical solutions are obtained for a simple soliton model.

Abstract

A phase soliton is a topological defect peculiar to two-band superconductors, which is associated with a $2\pi$ winding of the relative phase of the two superconducting condensates. We study the quasiparticle spectrum in the presence of a single planar phase soliton. We show that the order parameter phase variation in each of the bands leads to the existence of subgap states bound to the soliton. Calculation of the soliton energy valid at all temperatures is presented, with the exact analytical results obtained for a simple soliton model.