Gate-mediated transition between antiferromagnetic topological and Chern insulators in honeycomb X3MnN3 (X=Sr,Ba)

Abstract

Interest in antiferromagnetic (AFM) spintronics has been greatly stimulated by both the complex interplay between antiferromagnetism and band topology and the electrical switching of exotic properties they give rise to. However, the topological phase transitions are usually associated with magnetic transitions where the AFM ordering may be heavily deformed and limit their promising applications. Here, by first-principles calculations and a tight-binding model, we show that an electrically controlled topological phase transition with robust AFM ordering is possible in a honeycomb lattice, and remarkably the long-awaited AFM quantum anomalous Hall effect is obtained. The calculated spin Chern number and Chern number for a two-dimensional AFM topological insulator and AFM Chern insulator are, respectively, ${\mathcal{C}}_{\mathcal{S}}=1$ and $\mathcal{C}=1$, which are further explicitly confirmed by the corresponding helical and chiral edge states. Moreover, we identify intrinsic AFM ${X}_{3}\mathrm{Mn}{\mathrm{N}}_{3}$ $(X=\mathrm{Sr},\mathrm{Ba})$ bilayers as probable candidates for the experimental realization of the proposed phenomenon, and unexpectedly point out that the valley polarization of AFM ${X}_{3}\mathrm{Mn}{\mathrm{N}}_{3}$ is much larger than that of the known ferrovalley systems, indicating the high possibility of innovative applications in AFM spintronics and valleytronics.