Scaling Behavior of the Quantum Phase Transition from a Quantum Anomalous Hall Insulator to an Axion Insulator

TL;DR

This paper investigates the universal scaling behavior of the quantum phase transition from a quantum anomalous Hall insulator to an axion insulator, revealing a power-law temperature dependence and a critical exponent consistent with the Chalker-Coddington model.

Contribution

It demonstrates the universal scaling law and critical exponent for the QAH to axion insulator transition, supported by experimental data and theoretical modeling.

Findings

Power-law temperature dependence of the transition point derivative.

Critical exponent k approximately 0.38 consistent with Chalker-Coddington model.

Transition behavior similar to quantum Hall plateau transitions.

Abstract

The phase transitions from one plateau to the next plateau or to an insulator in quantum Hall and quantum anomalous Hall (QAH) systems have revealed universal scaling behaviors. A magnetic-field-driven quantum phase transition from a QAH insulator to an axion insulator was recently demonstrated in magnetic topological insulator sandwich samples. Here, we show that the temperature dependence of the derivative of the longitudinal resistance on magnetic field at the transition point follows a characteristic power-law that indicates a universal scaling behavior for the QAH to axion insulator phase transition. Similar to the quantum Hall plateau to plateau transition, the QAH to axion insulator transition can also be understood by the Chalker-Coddington network model. We extract a critical exponent k~ 0.38 in agreement with recent high-precision numerical results on the correlation length exponent of the Chalker-Coddington model at v ~ 2.6, rather than the generally-accepted value of 2.33.