We investigate an effective model of proximity modified graphene (or symmetrylike materials) with broken time-reversal symmetry. We predict the appearance of quantum anomalous Hall phases by computing bulk band gap and Chern numbers for benchmark combinations of system parameters. Allowing for staggered exchange field enables quantum anomalous Hall effect in flat graphene with Chern number $C=1$. We explicitly show edge states in zigzag and armchair nanoribbons and explore their localization behavior. Remarkably, the combination of staggered intrinsic spin-orbit and uniform exchange coupling gives topologically protected (unlike in time-reversal systems) pseudohelical states, whose spin is opposite in opposite zigzag edges. Rotating the magnetization from out of plane to in plane makes the system trivial, allowing us to control topological phase transitions. We also propose, using density functional theory, a material platform—graphene on Ising antiferromagnet ${\mathrm{MnPSe}}_3$—to realize staggered exchange (pseudospin Zeeman) coupling.

• Received 28 May 2019
• Revised 27 December 2019
• Accepted 27 January 2020

DOI:https://doi.org/10.1103/PhysRevLett.124.136403