Proximity-induced Majorana hinge modes in antiferromagnetic topological insulators

TL;DR

This paper proposes a method to realize chiral Majorana modes on the hinges of 3D antiferromagnetic topological insulators, specifically in MnBi2Te4-related materials, with potential experimental detection via conductance measurements.

Contribution

It introduces a novel approach to generate Majorana hinge modes in antiferromagnetic topological insulators through proximity effects and predicts experimental signatures.

Findings

Majorana hinge modes can be realized on the edges of antiferromagnetic topological insulators.

Proximity coupling to s-wave superconductors gaps certain surfaces, enabling Majorana modes.

Two-terminal conductance measurements can detect these Majorana hinge modes.

Abstract

We propose a realization of chiral Majorana modes propagating on the hinges of a 3D antiferromagnetic topological insulator, which was recently theoretically predicted and experimentally confirmed in the tetradymite-type $\mathrm{MnBi_2Te_4}$-related ternary chalgogenides. These materials consist of ferromagnetically ordered 2D layers, whose magnetization direction alternates between neighboring layers, forming an antiferromagnetic order. Besides surfaces with a magnetic gap, there also exsist gapless surfaces with a single Dirac cone, which can be gapped out when proximity coupled to an $s$-wave superconductor. On the sharing edges between the two types of gapped surfaces, the chiral Majorana modes emerge. We further propose experimental signatures of these Majoana hinge modes in terms of two-terminal conductance measurements.