# In-Plane Magnetization Induced Quantum Anomalous Hall Effect in Atomic Crystals of Group-V Elements

## TL;DR

This paper theoretically demonstrates the possibility of realizing the quantum anomalous Hall effect with in-plane magnetization in atomic layers of group-V elements, showing potential for high-temperature applications through tuning spin-orbit coupling and strain.

## Contribution

The study constructs a tight-binding model and predicts in-plane magnetization-induced QAHE with tunable Chern numbers and band gaps in group-V atomic crystals, highlighting experimental feasibility.

## Key findings

- QAHE with Chern numbers ±1 and ±2 identified.
- Small critical magnetization can be tuned by spin-orbit coupling.
- Large band gaps suggest room-temperature QAHE is possible.

## Abstract

We theoretically demonstrate that the in-plane magnetization induced quantum anomalous Hall effect (QAHE) can be realized in atomic crystal layers of group-V elements with buckled honeycomb lattice. We first construct a general tight-binding Hamiltonian with $sp^3$ orbitals via Slater-Koster two-center approximation, and then numerically show that for weak and strong spin-orbit couplings the systems harbor QAHEs with Chern numbers of $\mathcal{C}=\pm1$ and $\pm2$ , respectively. For the $\mathcal{C}=\pm1$ phases, we find the critical phase-transition magnetization from a trivial insulator to QAHE can become extremely small by tuning the spin-orbit coupling strength. Although the resulting band gap is small, it can be remarkably enhanced by orders via tilting the magnetization slightly away from the in-plane orientation. For the $\mathcal{C}=\pm2$ phases, we find that the band gap is large enough for the room-temperature observation. Although the critical magnetization is relatively large, it can be effectively decreased by applying a strain. All these suggest that it is experimentally feasible to realize high-temperature QAHE from in-plane magnetization in atomic crystal layers of group-V elements.