Topological superconductivity in Dirac honeycomb systems

TL;DR

This paper predicts two novel topological superconducting phases in Dirac honeycomb systems, characterized by unique pairing symmetries and topological properties, using self-consistent Bogoliubov--de Gennes theory on the Kane-Mele model.

Contribution

It introduces two new topological superconducting phases arising from valley Berry phases in gapped Dirac honeycomb systems, expanding the understanding of topological superconductivity.

Findings

Identification of a topological helical spin-triplet superconductor with nonzero momentum

Discovery of a topological chiral-triplet superconductor with Chern number ±1

Analysis of interactions U, V, J in the Kane-Mele model leading to these phases

Abstract

We predict two topological superconducting phases in microscopic models arising from the Berry phase associated with the valley degree of freedom in gapped Dirac honeycomb systems. The first one is a topological helical spin-triplet superconductor with a nonzero center-of-mass momentum that does not break time-reversal symmetry. We also find a topological chiral-triplet superconductor with Chern number $\pm 1$ with equal-spin-pairing in one valley and opposite-spin-triplet pairing in the other valley. Our results are obtained for the Kane-Mele model in which we have explored the effect of three different interactions, onsite attraction $U$, nearest-neighbor density-density attraction $V$, and nearest-neighbor antiferromagnetic exchange $J$, within self-consistent Bogoliubov--de Gennes theory. Transition metal dichalcogenides and cold atom experiments are promising platforms to explore these phases.