Hinged Quantum Spin-Hall Effect in Antiferromagnetic Topological Insulators

TL;DR

This paper predicts a new type of topological effect called hinged quantum spin-Hall (HQSH) in antiferromagnetic topological insulator multilayers, featuring helical hinge modes that are robust against TRS-breaking and inelastic scattering.

Contribution

It introduces the concept of HQSH effect in AFM TIs, characterized by helical hinge modes surviving TRS-breaking, and links it to a 3D generalization of the SSH model with topology given by the spin Chern number.

Findings

HQSH effect predicted in AFM topological insulator multilayers.

Helical hinge modes are robust against TRS-breaking and inelastic scattering.

Potential realization in MnBi2Te4-based materials and magnetic-doped TIs.

Abstract

In this work, we predict a hinged quantum spin-Hall (HQSH) effect featured by a pair of helical hinge modes in antiferromagnetic (AFM) topological insulator (TI) multilayers. This pair of helical hinge modes are localized on the hinges of the top and bottom surfaces of the AFM TI multilayers. Unlike the conventional QSH effect, the HQSH effect survives the breaking of time-reversal symmetry (TRS) and thus represents a different kind of topological phenomenon. The helical hinge modes are sustainable to inelastic scattering and TRS-breaking disorder, which can be observed in macroscopic samples. We show that this HQSH effect can be understood as a three-dimensional generalization of the Su-Schrieffer-Heeger model and its topology is characterized by the spin Chern number. At last, we propose that the HQSH effect can be realized in newly found intrinsic AFM TI materials (MnBi$_2$Te$_4$)$_m$(Bi$_2$Te$_3$)$_n$ or magnetic-doped TI multilayers by current experimental setups.