Observation of the quantum-anomalous-Hall insulator to Anderson   insulator quantum phase transition and its scaling behavior
  Fundamental insight into the nature of the quantum phase transition from a superconductor to an insulator in two dimensions, or from one plateau to the next or to an insulator in quantum Hall effect, has been revealed through the study of its scaling behavior. Here, we report on the experimental observation of a quantum phase transition from a quantum-anomalous-Hall (QAH) insulator to an Anderson insulator in a magnetic topological insulator by tuning the chemical potential. Our experiment demonstrates the existence of scaling behavior from which we extract the critical exponent for this quantum phase transition. We expect that our work will motivate much further investigation of many properties of quantum phase transition in this new context. 
Cui-Zu Chang, Weiwei Zhao, Jian Li, J. K. Jain, Chaoxing Liu,   Jagadeesh. S. Moodera and Moses H. W. Chan
cond-mat.mes-hall