Chern number-bandgap tunable quantum anomalous Hall effect in two-dimensional 1T-LaN2

Abstract

Materials exhibiting the quantum anomalous Hall effect (QAHE) with a high Chern number and a wide bandgap support multiple dissipationless chiral edge channels, thereby enhancing device performance. However, QAHE systems that simultaneously feature a wide bandgap and a high Chern number remain rare. Through first-principles calculations and group theory analysis, we demonstrate that the 1T-LaN2 monolayer—a two-dimensional rare-earth metal dinitride—can realize QAHE with highly tunable Chern numbers-bandgaps by adjusting the magnetization direction. A high-Chern-number QAHE phase (C=±3) emerges when the magnetization possesses a nonzero out-of-plane (z-axis) component, even under canted magnetic configurations. In contrast, a lower-Chern-number phase (C=±1) appears periodically when the magnetic moment breaks all twofold rotational symmetries within the x–y plane. Furthermore, fully out-of-plane magnetization opens a substantially large bandgap of 90.8 meV, making room-temperature QAHE feasible. We establish the phase diagram of magnetization-induced topological transitions and propose a realistic 1T-LaN2/InSe heterostructure capable of supporting nontrivial topological properties. Remarkably, this heterostructure leads to nontrivial topological half-metallic features, exhibiting a strongly valley-polarized state, highlighting its great potential for next-generation, low-power spintronic devices.