Recently, the intrinsic magnetic topological insulator ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ has attracted enormous research interest due to the great success in realizing exotic topological quantum states, such as the quantum anomalous Hall effect, the axion insulator state, and high-Chern-number and high-temperature Chern insulator (CI) states. One key issue in this field is to effectively manipulate these states and control topological phase transitions. Here, by systematic angle-dependent transport measurements, we reveal a magnetization-tuned topological quantum phase transition from CI to magnetic insulator with gapped Dirac surface states in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ devices. Specifically, as the magnetic field is tilted away from the out-of-plane direction by ∼40–60 °, the Hall resistance 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 CI to magnetic insulator with gapped Dirac surface states in ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ devices. These findings reveal a kind of topological phase transition associated with magnetism and spin-orbit coupling. In this letter, we suggest that ${\mathrm{MnBi}}_2{\mathrm{Te}}_4$ is an ideal platform for exploring topological quantum phase transitions, and it provides an efficient means for modulating topological quantum states and topological quantum phase transitions.

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• Anisotropic magnetoresistance
• Quantum anomalous Hall effect
• Antiferromagnets
• Chern insulators
• Devices
• Single crystal materials
• Hall bar
• Magnetization measurements
• Resistivity measurements