Chern Number Tunable Quantum Anomalous Hall Effect in Compensated Antiferromagnets.

Abstract

We propose to realize the quantum anomalous Hall effect (QAHE) in two-dimensional compensated antiferromagnets without net spin magnetization. We consider antiferromagnetic MnBi_{2}Te_{4} as a concrete example. By breaking the parity-time (PT) symmetry of even-layer MnBi_{2}Te_{4}, we find that the system can host the QAHE with a nonzero Chern number. We show that by controlling the antiferromagnetic spin configuration-for example, down/up/up/down that breaks PT symmetry-tetralayer MnBi_{2}Te_{4} can host a Chern number |C|=1. Such spin configuration can be stabilized by pinning the spin orientations of the surfaces. Furthermore, via tuning the on-site orbital energy and vertical electric fields, we find rich QAHE phases with tunable Chern number of |C|=1,2,3. In addition, we reveal that the edge states are layer selective and primarily located at the boundaries of the bottom and top layers. Our Letter not only proposes a scheme to realize Chern number tunable QAHE in antiferromagnets without net spin magnetization but also provides a platform for layer-selective dissipationless transport devices.