After decades of searching for the dissipationless transport in the absence
of any external magnetic field, quantum anomalous Hall effect (QAHE) was
recently achieved in magnetic topological insulator (TI) films. However, the
universal phase diagram of QAHE and its relation with quantum Hall effect (QHE)
remain to be investigated. Here, we report the experimental observation of the
giant longitudinal resistance peak and zero Hall conductance plateau at the
coercive field in the 6 quintuple-layer (Cr0.12Bi0.26Sb0.62)2Te3 film, and
demonstrate the metal-to-insulator switching between two opposite QAHE plateau
states up to 0.3 K. Moreover, the universal QAHE phase diagram is realized
through the angle-dependent measurements. Our results address that the quantum
phase transitions in both QAHE and QHE regimes are in the same universality
class, yet the microscopic details are different. In addition, the realization
of the QAHE insulating state unveils new ways to explore quantum phase-related
physics and applications