Chern Number Tunable Quantum Anomalous Hall Effect in Compensated Antiferromagnets
arxiv(2024)
摘要
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.
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