Prediction of high Curie-temperature intrinsic ferromagnetic semiconductors and quantum anomalous Hall states in XBr3 (X = Cu, Ag, Au) monolayers

XBr 3 (X = Cu, Ag, Au) monolayers are all found to be ferromagnetic semiconductors with high Curie temperatures (up to 149 K), dominated by super-exchange coupling. A topologically nontrivial state with a chiral edge state is obtained in CuBr 3 .