Observation of the quantum-anomalous-Hall insulator to Anderson insulator quantum phase transition and its scaling behavior

TL;DR

This paper reports the experimental observation of a quantum phase transition from a quantum-anomalous-Hall insulator to an Anderson insulator in a magnetic topological insulator, revealing its scaling behavior and critical exponent.

Contribution

It provides the first experimental evidence of this specific quantum phase transition and characterizes its scaling behavior and critical exponent.

Findings

Observation of the QAH to Anderson insulator transition.

Extraction of the critical exponent for the transition.

Demonstration of scaling behavior in the transition.

Abstract

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.