Quantum Anomalous Hall Effect in Antiferromagnetism

So far, experimentally realized quantum anomalous Hall (QAH) insulators all exhibit ferromagnetic order and the QAH effect only occurs at very low temperatures; Conceptually, the QAH effect is based on ferromagnetism or staggered flux. On the other hand, up to now the QAH effect in antiferromagnetic (AFM) systems has never been reported. In this letter, we realize the QAH effect by proposing a four-band lattice model with static AFM order, which indicates the QAH effect can be found in AFM materials with low lattice symmetry. Then, as a prototype, we demonstrate that a monolayer CrO can be switched from an AFM Weyl semimetal to an AFM QAH insulator by applying strain to lower its symmetry, based on theoretical analysis and the first-principles electronic structure calculations. Our work not only proposes a new scenario to search for QAH insulators,but also reveals a way to considerably increase the critical temperature of the QAH phase.