Quantum Anomalous Hall Effect in Antiferromagnetism

TL;DR

This paper demonstrates the theoretical possibility of realizing the quantum anomalous Hall effect in antiferromagnetic materials, specifically showing that monolayer CrO can switch from an AFM Weyl semimetal to an AFM QAH insulator under strain, opening new avenues for high-temperature QAH applications.

Contribution

It introduces a four-band lattice model with AFM order for QAH effect and shows strain-induced transition in monolayer CrO, expanding the search for QAH insulators in antiferromagnetic materials.

Findings

QAH effect can occur in AFM materials.

Strain can switch CrO from AFM Weyl semimetal to QAH insulator.

Potential to increase the critical temperature of QAH phases.

Abstract

So far, experimentally realized quantum anomalous Hall (QAH) insulators all exhibit ferromagnetic order and the QAH effect only occurs at very low temperatures. On the other hand, up to now the QAH effect in antiferromagnetic (AFM) materials has never been reported. In this letter, we realize the QAH effect by proposing a four-band lattice model with static AFM order, which indicates that the QAH effect can be found in AFM materials. Then, as a prototype, we demonstrate that a monolayer CrO can be switched from an AFM Weyl semimetal to an AFM QAH insulator by applying strain, based on symmetry analysis and the first-principles electronic structure calculations. Our work not only proposes a new scenario to search for QAH insulators in materials, but also reveals a way to considerably increase the critical temperature of the QAH phase.