Chern-insulator phase in antiferromagnets

TL;DR

This paper predicts and analyzes the possibility of realizing Chern insulators with quantum anomalous Hall effects in antiferromagnetic materials, expanding the scope beyond ferromagnets and proposing new material candidates.

Contribution

It introduces symmetry-based design principles and first-principles calculations to identify antiferromagnetic Chern insulators, including material examples like RbCr4S8 and Mn3Sn.

Findings

Antiferromagnetic Chern insulators can exist with in-plane magnetic configurations.

Material candidates such as monolayer RbCr4S8 and bilayer Mn3Sn are proposed.

Chern number can be tuned by slight ferromagnetic canting.

Abstract

The long-sought Chern insulators that manifest quantum anomalous Hall effect are typically considered to occur solely in ferromagnets. Here, we theoretically predict the realizability of Chern insulators in antiferromagnets, of which the magnetic sublattices are connected by symmetry operators enforcing zero net moment. Our symmetry analysis provides comprehensive magnetic layer point groups that allow antiferromagnetic (AFM) Chern insulators, and reveals that in-plane magnetic configuration is required. Followed by first-principles calculations, such design principles naturally lead to two categories of material candidates, exemplified by monolayer RbCr4S8 and bilayer Mn3Sn with collinear and noncollinear AFM orders, respectively. We further show that the Chern number could be tuned by slight ferromagnetic canting as an effective pivot. Our work elucidates the nature of Chern-insulator phase in AFM systems, paving a new avenue for the search and design of quantum anomalous Hall insulators with the integration of non-dissipative transport and the promising advantages of the AFM order.