Half-Magnetic Topological Insulator with Magnetization-Induced Dirac Gap at a Selected Surface
Half-Magnetic Topological Insulator with Magnetization-Induced Dirac Gap at a Selected Surface
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选定表面处具有磁化感应狄拉克间隙的半磁拓扑绝缘体
DOI：
10.1103/physrevx.11.011039
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发表时间：
2021-02-25
影响因子：
12.5
通讯作者：
Chen, Chaoyu
中科院分区：
文献类型：
--
作者：
Lu, Ruie;Sun, Hongyi;Chen, Chaoyu
拓扑磁体是一类新的量子材料，在实现量子反常霍尔效应和轴绝缘体态等涌现现象方面具有巨大的潜力。在这里，我们提出了我们的发现，化学计量的铁磁体MnBi 8 Te 13与自然异质结构MnBi 2 Te 4-（Bi 2 Te 3）3是一个前所未有的半磁性拓扑绝缘体，与磁化存在于MnBi 2 Te 4表面，但不是在相反的表面终止的三重Bi 2 Te 3层。我们的角分辨光电子能谱测量揭示了一个巨大的狄拉克间隙在MnBi 2 Te 4表面，和无间隙的狄拉克锥的另一边。值得注意的是，在MnBi 2 Te 4表面的狄拉克间隙（~28 meV）随着温度的升高而单调减小，并在居里温度处关闭，从而代表了所有已知磁性拓扑材料中磁化诱导拓扑表面间隙的第一个吸烟枪光谱证据。我们进一步从理论上证明了半磁性拓扑绝缘体是实现半量子化表面反常霍尔效应的理想材料，这为凝聚态系统中轴子电动力学的一般概念提供了直接的证明.
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.