Electron correlation and incipient flat bands in the Kagome superconductor CsCr3Sb5
Yidian Li, Yi Liu, Xian Du, Siqi Wu, Wenxuan Zhao, Kaiyi Zhai, Yinqi Hu, Senyao Zhang, Houke Chen, Jieyi Liu, Yiheng Yang, Cheng Peng, Makoto Hashimoto, Dong-Hui Lu, Zhongkai Liu, Yilin Wang, Yulin Chen, Guang‐Han Cao, Lexian Yang
Abstract
Correlated kagome materials exhibit a compelling interplay between lattice geometry, electron correlation, and topology. In particular, the flat bands near the Fermi level provide a fertile playground for novel many-body states. Here we investigate the electronic structure of CsCr3Sb5 using high-resolution angle-resolved photoemission spectroscopy and ab-initio calculations. Our results suggest that Cr 3d electrons are intrinsically incoherent, showing strong electron correlation amplified by Hund’s coupling. Notably, we identify incipient flat bands close to the Fermi level, which are expected to significantly influence the electronic properties of the system. Across the density-wave-like transition at 55 K, we observe a drastic enhancement of the electron scattering rate, which aligns with the semiconducting-like property at high temperatures. These findings establish CsCr3Sb5 as a strongly correlated Hund’s metal with incipient flat bands near the Fermi level, which provides an electronic basis for understanding its novel properties compared to the weakly correlated AV3Sb5. The authors investigate the electronic structure of kagome CsCr3Sb5 using high-resolution angle-resolved photoemission spectroscopy and ab-initio calculations. The results identify CsCr3Sb5 as a strongly correlated Hund’s metal with incipient flat bands near the Fermi level.