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arXiv · 2009.04140

Half-Magnetic Topological Insulator

Ruie Lu·Hongyi Sun·Shiv Kumar·Yuan Wang·Mingqiang Gu·Meng Zeng·Yu-Jie Hao·Jiayu Li·Jifeng Shao·Xiao-Ming Ma·Zhanyang Hao·Ke Zhang·Wumiti Mansuer·Jiawei Mei·Yue Zhao·Cai Liu·Ke Deng·Wen Huang·Bing Shen·Kenya Shimada·Eike F. Schwier·Chang Liu·Qihang Liu·Chaoyu Chen
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Abstract

Topological magnets are a new family of quantum materials providing great potential to realize emergent phenomena, such as quantum anomalous Hall effect and axion-insulator state. Here we present our discovery that stoichiometric ferromagnet MnBi8Te13 with natural heterostructure MnBi2Te4-(Bi2Te3)3 is an unprecedented half-magnetic topological insulator, with the magnetization existing at the MnBi2Te4 surface but not at the opposite surface terminated by triple Bi2Te3 layers. Our angle-resolved photoemission spectroscopy measurements unveil a massive Dirac gap at the MnBi2Te4 surface, and gapless Dirac cone on the other side. Remarkably, the Dirac gap (~28 meV) at MnBi2Te4 surface decreases monotonically with increasing temperature and closes right at the Curie temperature, thereby representing the first smoking-gun spectroscopic evidence of magnetization-induced topological surface gap among all known magnetic topological materials. We further demonstrate theoretically that the half-magnetic topological insulator is desirable to realize the half-quantized surface anomalous Hall effect, which serves as a direct proof of the general concept of axion electrodynamics in condensed matter systems.

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Ruie Lu, Hongyi Sun, Shiv Kumar, Yuan Wang, Mingqiang Gu, Meng Zeng, Yu-Jie Hao, Jiayu Li, Jifeng Shao, Xiao-Ming Ma, Zhanyang Hao, Ke Zhang, Wumiti Mansuer, Jiawei Mei, Yue Zhao, Cai Liu, Ke Deng, Wen Huang, Bing Shen, Kenya Shimada, Eike F. Schwier, Chang Liu, Qihang Liu, Chaoyu Chen. 2020-09-09. Half-Magnetic Topological Insulator. https://doi.org/10.1103/physrevx.11.011039

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