Chern Number Tunable Quantum Anomalous Hall Effect in Compensated Antiferromagnets

We propose to realize quantum anomalous Hall effect (QAHE) in two-dimensional antiferromagnetic topological insulators. We consider antiferromagnetic MnBi_2Te_4 as a concrete example. In contrast to the even-layer A-type antiferromagnetic MnBi_2Te_4 that has zero Chern number due to the combined parity-time (𝒫𝒯) symmetry, the system can host a nonzero Chern number by breaking this symmetry. We show that by controlling the antiferromagnetic spin configuration, for example, down/up/up/down, to break 𝒫𝒯 symmetry, tetralayer antiferromagnetic MnBi_2Te_4 can realize QAHE with Chern number 𝒞=-1. Such spin configuration can be stablized by pinning the spin orientations on top and bottom layers. Furthermore, we reveal that the edge states are layer-selective and primarily locate at the boundaries of the bottom and top layers. In addition, via tuning the on-site orbital energy which determines the inverted band gap, we find tunable Chern number from 𝒞=-1 to 𝒞=2 and then to 𝒞=-1. Our work not only proposes a scheme to realize Chern number tunable QAHE in antiferromagnets without net spin magnetization, but also provide a platform for layer-selective dissipationless transport devices.