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Pressure-Tunable Phase Transitions in Atomically Thin Chern Insulator MnBi2Te4
Albin Márffy1,2, Endre Tóvári1,2, Yu-Fei Liu3,4
1Department of Physics, Budapest University of Technology and Economics, Müegyetem rkp. 3., H-1111 Budapest, Hungary.
Nano Letters
|January 29, 2026
Summary
Odd-layer MnBi2Te4, a magnetic topological insulator, rarely shows the quantum anomalous Hall effect. Studies reveal a trivial insulator state due to disorder, but a Chern insulator state emerges in high magnetic fields.
Area of Science:
- Condensed matter physics
- Materials science
- Quantum phenomena
Background:
- Topological insulators (TIs) with broken time-reversal symmetry can host the quantum anomalous Hall effect (QAHE).
- MnBi2Te4 is an intrinsic magnetic TI material, making it a promising candidate for observing QAHE, but experimental realization remains challenging.
Purpose of the Study:
- Investigate the electronic transport properties of odd-layer thick MnBi2Te4.
- Determine the conditions under which QAHE or related topological states emerge in this material.
- Understand the influence of external stimuli like magnetic fields and hydrostatic pressure on the magnetic and topological properties.
Main Methods:
- Magnetoresistance measurements were performed on odd-layer thick MnBi2Te4 samples.
- Experiments were conducted in the antiferromagnetic phase and under varying magnetic fields and temperatures.
- Hydrostatic pressure was applied to study its effect on magnetic coupling and band structure.
Main Results:
- In the antiferromagnetic phase, a trivial insulator state, attributed to disorder, was observed instead of the expected QAHE.
- A Chern insulator state was found to emerge under a high magnetic field.
- Hydrostatic pressure was found to enhance interlayer exchange coupling while weakening intralayer coupling.
- The trivial band gap decreased under pressure, indicating a reduced role of disorder.
Conclusions:
- Disorder plays a significant role in suppressing the QAHE in MnBi2Te4.
- A high magnetic field can induce a topological phase transition to a Chern insulator state.
- Hydrostatic pressure offers a route to tune the magnetic exchange interactions and potentially mitigate disorder effects in MnBi2Te4.
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