Exchange field-induced topological phase transition in ultrathin films of three-dimension topological insulators

We investigate the topological phase transition in ultrathin films of three-dimension topological insulators, induced by a rotation of the exchange field. It is found that, as the exchange field rotates from the vertical to the horizontal orientation, there is a topological phase transition from a quantum anomalous Hall phase to the trivial insulating one at a critical angle, yielding an angular-dependent quantum magnetoresistance.