Electric control of a canted-antiferromagnetic Chern insulator

Nontrivial band topology and magnetic order meet in a topological magnet to produce novel topological phase of matters, such as quantum anomalous Hall insulator. While prior works have focused on ferromagnetic systems, little is known about band topology and its manipulation in antiferromagnets. Here, we report that MnBi₂Te₄ realizes a canted-antiferromagnetic (cAFM) Chern insulator with electrical control. We show that the Chern insulator state with C = 1 appears as soon as the AFM to canted-AFM phase transition happens. Near the phase boundary of cAFM and AFM phases, an electric field can switch the transport between dissipative or dissipationless transport. Our dual-gated RMCD measurement rules out magnetoelectric effects as the tuning mechanism and suggests a picture that electric field controls the relative alignment of the magnetic exchange gap between top and bottom surfaces.