Chiral Majorana Fermions in two dimensional square lattice antiferromagnet with proximity-induced superconductivity

TL;DR

This paper demonstrates that in a two-dimensional square-lattice antiferromagnet with spin-orbit coupling, proximity-induced superconductivity and exchange fields can create topological phases hosting chiral Majorana edge states, with specific conditions on pairing and exchange non-uniformity.

Contribution

It introduces a lattice model for topological superconductivity in antiferromagnets and identifies conditions for chiral Majorana edge states in this system.

Findings

Non-uniform pairing or exchange fields are necessary for topological phases.

The BdG Chern number can be ±1 or ±3, indicating the number of Majorana edge state pairs.

Nanoribbons exhibit one or three pairs of chiral Majorana edge states depending on the phase.

Abstract

Combination of proximity-induced superconductivity and ferromagnetic exchange field in a two-dimensional square-lattice antiferromagnet with spin-orbit coupling and nonsymmorphic symmetry can induce a topological superconductor phase with chiral Majorana edge states. The lattice model of the Bogoliubov-de Gennes (BdG) Hamiltonian was applied to study the phase diagram of bulks and chiral Majorana edge states in nanoribbons. By numerically studying the phase diagram, we found that the non-uniformity of either the superconducting pairing parameters or the exchange field at the two sublattices is necessary to induce a topological superconductor phase with chiral Majorana edge states. The BdG Chern number of certain topological superconductor phases is $\pm1$ or $\pm3$, such that the corresponding nanoribbons have one or three pairs of chiral Majorana edge states, respectively.