Antiferromagnetic Quantum Anomalous Hall Effect Under Spin Flips and Flops
ORAL · Invited
Abstract
The interplay between nontrivial band topology and layered antiferromagnetism in MnBi2Te4 opens a new avenue for exploring topological phases of matter. The rich and complex spin dynamics associated with the van der Waals antiferromagnetic order is expected to generate novel topological phases and phase transitions that are unique to MnBi2Te4. The quantum anomalous Hall effect and axion insulator state have been observed in odd- and even-septuple-layer (SL) of MnBi2Te4 respectively. However, it has been a challenging task to fabricate devices that exhibit quantized transport [1].
In this talk, we present the transport studies of a 7-SL MnBi2Te4 device covered with AlOx capping layer, which enhances the perpendicular magnetic anisotropy and enables the investigation of antiferromagnetic quantum anomalous Hall effect over wide parameter ranges. By tuning the gate voltage and perpendicular magnetic field, we uncover a cascade of quantum phase transitions that can be attributed to the influence of spin configurations on edge state charge transport [2]. Furthermore, we find that an in-plane magnetic field enhances both the coercive field and exchange gap of the surface state, in sharp contrast to that in ferromagnetic quantum anomalous Hall state. These phenomena become even more pronounced when both sides of the MnBi2Te4 flake are covered with AlOx [3]. We propose that these peculiar features arise from the spin flip and flop transitions inherent to layered van der Waals antiferromagnet. The versatile tunability of the quantum anomalous Hall effect in MnBi2Te4 paves the way for potential applications in topological antiferromagnetic spintronics.
References
[1] Y.X. Li et al., Nature Communications 15, 3399 (2024).
[2] Z.C. Lian et al., Nature 641, 70 (2025).
[3] Z.C. Lian et al., Science Bulletin 70, 3139 (2025).
In this talk, we present the transport studies of a 7-SL MnBi2Te4 device covered with AlOx capping layer, which enhances the perpendicular magnetic anisotropy and enables the investigation of antiferromagnetic quantum anomalous Hall effect over wide parameter ranges. By tuning the gate voltage and perpendicular magnetic field, we uncover a cascade of quantum phase transitions that can be attributed to the influence of spin configurations on edge state charge transport [2]. Furthermore, we find that an in-plane magnetic field enhances both the coercive field and exchange gap of the surface state, in sharp contrast to that in ferromagnetic quantum anomalous Hall state. These phenomena become even more pronounced when both sides of the MnBi2Te4 flake are covered with AlOx [3]. We propose that these peculiar features arise from the spin flip and flop transitions inherent to layered van der Waals antiferromagnet. The versatile tunability of the quantum anomalous Hall effect in MnBi2Te4 paves the way for potential applications in topological antiferromagnetic spintronics.
References
[1] Y.X. Li et al., Nature Communications 15, 3399 (2024).
[2] Z.C. Lian et al., Nature 641, 70 (2025).
[3] Z.C. Lian et al., Science Bulletin 70, 3139 (2025).
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Presenters
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Yayu Wang
- Tsinghua University