The topological quantum phases in antiferromagnetic topological insulator MnBi2Te4 hold promise for next-generation spintronics, but their experimental realization has been constrained by challenges in preparing high-quality devices. In this work, we report a new wax-assisted exfoliation and transfer method that enables the fabrication of MnBi2Te4 heterostructures with both surfaces encapsulated by AlOx. This strategy strongly enhances the topological quantum phases in MnBi2Te4 flakes. We observe the robust axion insulator state in even-layer device with wide zero Hall plateau and high longitudinal resistivity, and the quantum anomalous Hall effect in odd-layer device with large hysteresis and sharp plateau transition. These results demonstrate that the combination of wax exfoliation and AlOx encapsulation provides great potentials for exploring novel topological quantum phenomena and potential applications in MnBi2Te4 and other two-dimensional materials.
@article{arxiv.2506.04901,
title = {Strongly enhanced topological quantum phases in dual-surface AlO$_x$-encapsulated MnBi$_2$Te$_4$},
author = {Zichen Lian and Yongqian Wang and Yongchao Wang and Liangcai Xu and Jinsong Zhang and Chang Liu and Yayu Wang},
journal= {arXiv preprint arXiv:2506.04901},
year = {2025}
}