Competing topological superconducting phases in FeSe$_{0.45}$Te$_{0.55}$

TL;DR

This paper provides evidence for two distinct topological superconducting phases in FeSe$_{0.45}$Te$_{0.55}$, stabilized by different microscopic mechanisms, and discusses their Majorana edge modes and phase diagram.

Contribution

It identifies and characterizes two competing topological superconducting phases in FeSe$_{0.45}$Te$_{0.55}$ based on experimental data and theoretical analysis.

Findings

Evidence for two topological superconducting phases

Distinct microscopic mechanisms stabilize each phase

Identification of Majorana edge modes at domain walls

Abstract

We demonstrate that recent angle-resolved photo-emission spectroscopy experiments provide strong evidence for the existence of two competing topological superconducting phases in FeSe$_{0.45}$Te$_{0.55}$. The coupling of their underlying microscopic mechanisms -- one based on a three-dimensional topological insulator, one based on two-dimensional superconductivity -- stabilizes topological superconductivity over a wide range of parameters, and gives rise to two disjoint topological regions in the phase diagram of FeSe$_{0.45}$Te$_{0.55}$. We show that the topological origin of these regions can be identified by considering the form of Majorana edge modes at domain walls.