Emergence of New van Hove Singularities in the Charge Density Wave State of a Topological Kagome Metal <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>RbV</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Sb</mml:mi></mml:mrow><mml:mrow><mml:mn>5</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:mrow></mml:math>
Soohyun Cho, Haiyang Ma, Wei Xia, Yichen Yang, Zhengtai Liu, Zhe Huang, Zhicheng Jiang, Xiangle Lu, Jishan Liu, Zhonghao Liu, Jun Li, Jinghui Wang, Yi Liu, Jinfeng Jia, Yanfeng Guo, Jianpeng Liu, Dawei Shen
Abstract
Quantum materials with layered kagome structures have drawn considerable attention due to their unique lattice geometry, which gives rise to flat bands together with Dirac-like dispersions. Recently, vanadium-based materials with layered kagome structures were discovered to be topological metals, which exhibit charge density wave (CDW) properties, significant anomalous Hall effect, and unusual superconductivity at low temperatures. Here, we employ angle-resolved photoemission spectroscopy to investigate the electronic structure evolution upon the CDW transition in a vanadium-based kagome material ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$. The CDW phase transition gives rise to a partial energy gap opening at the boundary of the Brillouin zone and, most importantly, the emergence of new van Hove singularities associated with large density of states, which are absent in the normal phase and might be related to the superconductivity observed at lower temperatures. Our work sheds light on the microscopic mechanisms for the formation of the CDW and superconducting states in these topological kagome metals.