Engineering Plateau Phase Transition in Quantum Anomalous Hall Multilayers.

Abstract

The plateau phase transition in quantum anomalous Hall (QAH) insulators corresponds to a quantum state wherein a single magnetic domain gives way to multiple domains and then reconverges back to a single magnetic domain. The layer structure of the sample provides an external knob for adjusting the Chern number <i>C</i> of the QAH insulators. Here, we employ molecular beam epitaxy to grow magnetic topological insulator multilayers and realize the magnetic field-driven plateau phase transition between two QAH states with odd Chern number change Δ<i>C</i>. We find that critical exponents extracted for the plateau phase transitions with Δ<i>C</i> = 1 and Δ<i>C</i> = 3 in QAH insulators are nearly identical. We construct a four-layer Chalker-Coddington network model to understand the consistent critical exponents for the plateau phase transitions with Δ<i>C</i> = 1 and Δ<i>C</i> = 3. This work will motivate further investigations into the critical behaviors of plateau phase transitions with different Δ<i>C</i> in QAH insulators.