Edge states and local electronic structure around an adsorbed impurity in a topological superconductor

TL;DR

This paper investigates the edge states and local electronic structure in a topological superconductor with specific pairing symmetry, revealing gapless edge states and impurity-induced bound states, relevant to recent STM experiments.

Contribution

It predicts the existence of gapless edge states and impurity bound states in a topological superconductor with Z2 mirror order and s±-wave pairing, using a two-orbital model.

Findings

Existence of gapless edge states in the system

Low-energy in-gap bound states around magnetic impurities

Relevance to STM experiments on Fe(Te,Se) with spin-polarized impurities

Abstract

Recently topological superconducting states has attracted a lot of interest. In this work, we consider a topo- logical superconductor with $Z_2$ topological mirror order [1] and s$\pm$-wave superconducting pairing symmetry, within a two-orbital model originally designed for iron-based superconductivity [2]. We predict the existence of gapless edge states. We also study the local electronic structure around an adsorbed interstitial magnetic impurity in the system, and find the existence of low-energy in-gap bound states even with a weak spin polar- ization on the impurity. We also discuss the relevance of our results to the recent STM experiment on Fe(Te,Se) compound with adsorbed Fe impurity [3], for which our density functional calculations show the Fe impurity is spin polarized.