Scaling behavior of the quantum phase transition from a quantum anomalous Hall insulator to an axion insulator.

We performed the scaling behavior study of quantum phase transition from quantum anomalous Hall state(QAHS) to axion insulator state in magnetic topological insulator sandwich samples. A power-law dependence of the derivative of longitudinal resistance with magnetic field on temperature was observed at the transition point. We extracted the critical exponent κ ~ 0.38±0.02, which agrees well with the recent high precision calculation result of ν ~ 2.6 using the Chalker-Coddington network model in quantum Hall system. We also measured the resistance of the axion insulator state, which is as high as 1.3 GΩ at 50 mK using a quasi-DC measurement method. Our work indicates that the QAHS to axion insulator state transition shares the same universality class with the plateau to plateau transition in quantum Hall system.[1]
[1] Wu, X. et al, Nat. Commun. 11, 4532(2020)