Topological Phases in Nodeless Tetragonal Superconductors

TL;DR

This paper explores the topological phases of 2D tetragonal superconductors with nodeless pairing, revealing complex topological features like high Chern numbers and zero-energy modes under Zeeman and spin-orbit effects, with potential material applications.

Contribution

It provides the first detailed topological phase diagram for nodeless tetragonal superconductors, highlighting novel topological phenomena and their relevance to real materials.

Findings

Presence of high Chern number phases

Existence of zero-energy edge modes

Topologically protected edge states

Abstract

We compute the topological phase diagram of 2D tetragonal superconductors for the only possible nodeless pairing channels compatible with that crystal symmetry. Subject to a Zeeman field and spin-orbit coupling, we demonstrate that these superconductors show surprising topological features: non-trivial high Chern numbers, massive edge states, and zero-energy modes out of high symmetry points, even though the edge states remain topologically protected. Interestingly, one of these pairing symmetries, $d+id$, has been proposed to describe materials such as water-intercalated sodium cobaltates, bilayer silicene or highly doped monolayer graphene, which opens the way for further applications of our results.