Phase diagrams of superconducting topological surface states

TL;DR

This paper investigates the phase diagrams of superconducting topological surface states, emphasizing the role of crystalline symmetry and topology, and identifies conditions for chiral Majorana modes in certain superconducting films.

Contribution

It introduces a classification framework for topological phases in superconducting surface states considering mirror symmetry and pairing types, revealing new topological phases.

Findings

Mirror symmetry allows classification of BdG Hamiltonian into distinct topological phases.

Topologically non-trivial phases support chiral Majorana edge modes.

FeSeTe thin films can realize these topological superconducting phases.

Abstract

In this paper, we present a detailed study on the phase diagrams of superconducting topological surface states, especially, focusing on the interplay between crystalline symmetry and topology of the effective BdG Hamiltonian. We show that for the $4\times 4$ kinematic Hamiltonian of the normal state, a mirror symmetry $\mathcal{M}$ can be defined, and for the $\mathcal{M}$-odd pairings, the classification of the $8\times8$ BdG Hamiltonian is $\mathbb{Z}\oplus\mathbb{Z}$, and the time-reversal symmetry is broken intrinsically. The topological non-trivial phase can support chiral Majorana edge modes, and can be realized in the thin films of iron-based superconductor such as FeSeTe.