We theoretically report that, with \textit{in-plane} magnetization, the quantum anomalous Hall effect (QAHE) can be realized in two-dimensional atomic crystal layers with preserved inversion symmetry but broken out-of-plane mirror reflection symmetry. We take the honeycomb lattice as an example, where we find that the low-buckled structure, which makes the system satisfy the symmetric criteria, is crucial to induce QAHE. The topologically nontrivial bulk gap carrying a Chern number of C=±1 opens in the vicinity of the saddle points M, where the band dispersion exhibits strong anisotropy. We further show that the QAHE with electrically tunable Chern number can be achieved in Bernal-stacked multilayer systems, and the applied interlayer potential differences can dramatically decrease the critical magnetization to make the QAHE experimentally feasible.
@article{arxiv.1512.05887,
title = {Quantum anomalous Hall effect in atomic crystal layers from in-plane magnetization},
author = {Yafei Ren and Junjie Zeng and Xinzhou Deng and Fei Yang and Hui Pan and Zhenhua Qiao},
journal= {arXiv preprint arXiv:1512.05887},
year = {2017}
}