Optical anomalous Hall effect enhanced by flat bands in ferromagnetic van der Waals semimetal
Optical anomalous Hall effect enhanced by flat bands in ferromagnetic van der Waals semimetal
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DOI：
10.1038/s41535-022-00482-2
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发表时间：
2022-07-23
影响因子：
5.7
通讯作者：
Takahashi, Youtarou
中科院分区：
文献类型：
--
作者：
Kato, Yoshihiro D.;Okamura, Yoshihiro;Takahashi, Youtarou
凝聚态中电子态的几何方面导致了增强电磁现象的实验实现，如拓扑半金属中的巨反常霍尔效应（AHE）。然而，由于对实际电子结构中Berry曲率的来源缺乏深刻的理解，对大AHE的指导仍然不成熟，主要焦点仅集中在费米能级附近的带交叉。在这里，我们表明，带交叉和平带合作产生大的内在AHE铁磁节线半金属候选人Fe3GeTe2。太赫兹和红外磁光光谱表明，在光学霍尔电导率谱σ（xy）（ω）中的两个显式共振结构与AHE密切相关。第一性原理计算表明，具有大的态密度（DOS）的平坦带和费米能级附近的带交叉是这些霍尔共振的主要原因。我们的研究结果揭示了一种机制，以提高AHE的基础上的平带，这给洞察到拓扑材料的设计。
Geometrical aspects of electronic states in condensed matter have led to the experimental realization of enhanced electromagnetic phenomena, as exemplified by the giant anomalous Hall effect (AHE) in topological semimetals. However, the guideline to the large AHE is still immature due to lack of profound understanding of the sources of the Berry curvature in actual electronic structures; the main focus has concentrated only on the band crossings near the Fermi level. Here, we show that the band crossings and flat bands cooperatively produce the large intrinsic AHE in ferromagnetic nodal line semimetal candidate Fe3GeTe2. The terahertz and infrared magneto-optical spectroscopy reveals that two explicit resonance structures in the optical Hall conductivity spectra sigma(xy)(omega) are closely related to the AHE. The first-principles calculation suggests that both the flat bands having large density of states (DOS) and the band crossings near the Fermi level are the main causes of these Hall resonances. Our findings unveil a mechanism to enhance the AHE based on the flat bands, which gives insights into the topological material design.