Hybridization-induced gapped and gapless states on the surface of magnetic topological insulators
Hybridization-induced gapped and gapless states on the surface of magnetic topological insulators
复制标题
磁拓扑绝缘体表面杂化引起的有隙和无隙态
DOI：
10.1103/physrevb.102.245136
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发表时间：
2020-12-22
影响因子：
3.7
通讯作者：
Chen, Chaoyu
中科院分区：
文献类型：
--
作者：
Ma, Xiao-Ming;Chen, Zhongjia;Chen, Chaoyu
层状MnBi2nTe3n +1家族代表了有史以来发现的第一个本征反铁磁（AFM）拓扑绝缘体（由组合对称性S保护），为探索物理学的新领域提供了理想的平台，例如高温下的量子反常霍尔效应和轴子电动力学。最近的一些角度分辨光电子能谱（ARPES）实验表明，所有终端表现出（几乎）无间隙的拓扑表面状态（TSS）的AFM状态。无间隙行为与理论预期不一致，因为所研究的表面是S-破缺的，因此应该打开间隙。在这里，我们解释这个奇怪的悖论使用的表面-体带杂交图片。结合圆二色性ARPES和MnBi6Te 10的第一性原理计算，我们证明了通过TSS和某些具有Rashba特征的体带之间的杂交诱导的间隙特征。所观察到的（几乎）无缝的功能是一致的紧束缚模拟，其中TSS耦合到一对Rashba分裂带（RSBs）再现。类狄喇克锥的光谱特征实际上来源于RSBs。我们的研究结果突出的作用带杂化，上级在这种情况下，磁性，在塑造一般的表面带结构在这个家庭的磁性拓扑材料。
The layered MnBi2nTe3n+1 family represents the first intrinsic antiferromagnetic (AFM) topological insulator (protected by a combination symmetry S) ever discovered, providing an ideal platform to explore novel areas of physics such as the quantum anomalous Hall effect at elevated temperature and axion electrodynamics. Some of the recent angle-resolved photoemission spectroscopy (ARPES) experiments on this family have revealed that all terminations exhibit (nearly) gapless topological surface states (TSSs) in the AFM state. The gapless behavior is inconsistent with the theoretical expectation, as the surfaces being studied are S-breaking and shall therefore open a gap. Here we explain this curious paradox using a surface-bulk band hybridization picture. Combining circular dichroism ARPES and first-principles calculations on MnBi6Te10, we prove that gaplike features are induced through hybridization between TSSs and certain bulk bands with Rashba character. The observed (nearly) gapless features are consistently reproduced by tight-binding simulations where TSSs are coupled to a pair of Rashba-split bands (RSBs). The Dirac-cone-like spectral features actually originate from the RSBs. Our findings highlight the role of band hybridization, superior to magnetism in this case, in shaping the general surface band structure in this family of magnetic topological materials.