Thickness-driven and magnetization-tuned topological quantum phase transition in MnBi2Te4 devices

The intrinsic magnetic topological insulator MnBi₂Te₄ (MBT) hosts a variety of exotic quantum phenomena arising from the interplay between magnetism and topology. We previously discovered high-Chern-number (|C| = 2) and high-temperature Chern insulator states (|C| = 1, working temperature higher than 30 K) in MBT devices, revealing a thickness-driven topological phase transition from |C| = 2 to |C| = 1 [1]. Building on this progress, we further demonstrate a magnetization-tuned topological quantum phase transition in MBT devices [2]. Specifically, as the magnetic field is tilted away from the out-of-plane direction by ∼40–60 °, the Hall resistance in the MBT devices deviates from the quantization value, and a colossal, anisotropic magnetoresistance is detected. Theoretical analyses based on modified Landauer-Büttiker formalism show that the field-tilt-driven switching from the ferromagnetic state to the canted antiferromagnetic state induces a topological quantum phase transition from Chern insulator to magnetic insulator with gapped Dirac surface states in MBT devices. Furthermore, we demonstrate the robustness of chiral edge-state transport in patterned MBT devices. By making a narrow cut at the edge of MBT flakes using atomic force microscope tip-based nanomachining process, the shape of the device is dramatically changed. Nevertheless, systematic magnetotransport measurements reveal consistent quantization behavior of the Chern insulator states before and after cutting, providing a compelling evidence for the robustness of the chiral edge states [3]. These results establish MBT as an ideal platform for exploring tunable topological quantum phase transitions and robust edge transport, paving the way toward low-dissipation topological electronics.



To summarize the rapid progress in the study of intrinsic magnetic topological insulator MBT, we have written a comprehensive review that surveys the topological phase diagram and future opportunities for MBT and related materials, outlining a roadmap toward realizing novel topological quantum phases and their potential applications in low-power electronics, spintronics, and topological quantum computing [4].