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arXiv · 2107.08137

Delicate Ferromagnetism in MnBi$_6$Te$_{10}$

Chenhui Yan·Yanglin Zhu·Leixin Miao·Sebastian Fernandez-Mulligan·Emanuel Green·Ruobing Mei·Hengxin Tan·Binghai Yan·Chao-Xing Liu·Nasim Alem·Zhiqiang Mao·Shuolong Yang
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Abstract

Tailoring magnetic orders in topological insulators is critical to the realization of topological quantum phenomena. An outstanding challenge is to find a material where atomic defects lead to tunable magnetic orders while maintaining a nontrivial topology. Here, by combining magnetization measurements, angle-resolved photoemission spectroscopy, and transmission electron microscopy, we reveal disorder-enabled, tunable magnetic ground states in MnBi$_6$Te$_{10}$. In the ferromagnetic phase, an energy gap of 15 meV is resolved at the Dirac point on the MnBi$_2$Te$_4$ termination. In contrast, antiferromagnetic MnBi$_6$Te$_{10}$ exhibits gapless topological surface states on all terminations. Transmission electron microscopy and magnetization measurements reveal substantial Mn vacancies and Mn migration in ferromagnetic MnBi$_6$Te$_{10}$. We provide a conceptual framework where a cooperative interplay of these defects drives a delicate change of overall magnetic ground state energies, and leads to tunable magnetic topological orders. Our work provides a clear pathway for nanoscale defect-engineering towards the realization of topological quantum phases.

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Chenhui Yan, Yanglin Zhu, Leixin Miao, Sebastian Fernandez-Mulligan, Emanuel Green, Ruobing Mei, Hengxin Tan, Binghai Yan, Chao-Xing Liu, Nasim Alem, Zhiqiang Mao, Shuolong Yang. 2021-07-16. Delicate Ferromagnetism in MnBi$_6$Te$_{10}$. https://doi.org/10.1021/acs.nanolett.2c02500

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