In-plane magnetization-induced quantum anomalous Hall effect in atomic crystals of group-V elements

We theoretically demonstrate that the in-plane magnetization-induced quantum anomalous Hall effect (QAHE) can be realized in the atomic crystal layers of group-V elements with a buckled honeycomb lattice. Based on $s{p}³$ tight-binding models with parameters being extracted from first-principles results, we show that for weak and strong spin-orbit couplings, the systems harbor QAHEs with Chern numbers of $\mathcal{C}=\ifmmode\pm\else\textpm\fi{}1$ and $\ifmmode\pm\else\textpm\fi{}2$, respectively. For $\mathcal{C}=\ifmmode\pm\else\textpm\fi{}1$ phases, we find the critical magnetization to realize QAHE can be extremely small by tuning the spin-orbit coupling strength. For $\mathcal{C}=\ifmmode\pm\else\textpm\fi{}2$ phases, we find that although the critical magnetization is larger, it can be decreased effectively by strain. Moreover, the band gap is large enough for a room-temperature observation. These features suggest that it is experimentally feasible to realize high-temperature QAHEs from in-plane magnetization in the atomic crystal layers of group-V elements.