Wu Wenbin, Shi Zeping, Ozerov Mykhaylo, Du Yuhan, Wang Yuxiang, Ni Xiao-Sheng, Meng Xianghao, Jiang Xiangyu, Wang Guangyi, Hao Congming, Wang Xinyi, Zhang Pengcheng, Pan Chunhui, Pan Haifeng, Sun Zhenrong, Yang Run, Xu Yang, Hou Yusheng, Yan Zhongbo, Zhang Cheng, Lu Hai-Zhou, Chu Junhao, Yuan Xiang
State Key Laboratory of Precision Spectroscopy, East China Normal University, 200241, Shanghai, China.
Key Laboratory of Polar Materials and Devices, Ministry of Education, School of Physics and Electronic Science, East China Normal University, 200241, Shanghai, China.
Nat Commun. 2024 Mar 14;15(1):2313. doi: 10.1038/s41467-024-46626-9.
Arising from the extreme/saddle point in electronic bands, Van Hove singularity (VHS) manifests divergent density of states (DOS) and induces various new states of matter such as unconventional superconductivity. VHS is believed to exist in one and two dimensions, but rarely found in three dimension (3D). Here, we report the discovery of 3D VHS in a topological magnet EuCdAs by magneto-infrared spectroscopy. External magnetic fields effectively control the exchange interaction in EuCdAs, and shift 3D Weyl bands continuously, leading to the modification of Fermi velocity and energy dispersion. Above the critical field, the 3D VHS forms and is evidenced by the abrupt emergence of inter-band transitions, which can be quantitatively described by the minimal model of Weyl semimetals. Three additional optical transitions are further predicted theoretically and verified in magneto-near-infrared spectra. Our results pave the way to exploring VHS in 3D systems and uncovering the coordination between electronic correlation and the topological phase.
范霍夫奇点（VHS）源于电子能带中的极值点/鞍点，表现出发散的态密度（DOS），并诱导出各种新的物质状态，如非常规超导性。人们认为VHS存在于一维和二维体系中，但在三维（3D）体系中很少被发现。在此，我们通过磁红外光谱法报告了在拓扑磁体EuCdAs中发现三维VHS的情况。外部磁场有效地控制了EuCdAs中的交换相互作用，并使三维外尔能带连续移动，导致费米速度和能量色散的改变。在临界场以上，三维VHS形成，带间跃迁的突然出现证明了这一点，这可以用外尔半金属的最小模型进行定量描述。理论上进一步预测了另外三个光学跃迁，并在磁近红外光谱中得到了验证。我们的结果为探索三维体系中的VHS以及揭示电子关联与拓扑相之间的协同作用铺平了道路。
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