Correlated electron systems with topological flat bands show great promise in exploring exotic quantum phenomena. However, such crystalline materials remain rare. Here we report the discovery of a novel material, Cs3V9Te13, which unexpectedly exhibits magnetism and significant electron correlations. The crystal structure features two interpenetrating sets of vanadium triangles that can be linked with an ideal kagome lattice. The physical property measurements demonstrate a cascade of correlated electron phenomena, including quasi-two-dimensional bad metal, non-Fermi-liquid behavior, antiferromagnetic spin-density-wave transition at TN = 47 K, possible short-range spin ordering at ∼350 K, a large Sommerfeld coefficient of 246 mJ mol-fu−1 K−2, and pressure-induced quantum criticality. These correlated electron behaviors are associated with the topological flat bands at the Fermi level, the latter of which are generated from the V2 sublattice in terms of a bipartite kagome model. Our findings establish Cs3V9Te13 as a brand new correlated matter that synergistically combines flat-band physics and tunable properties.
@article{arxiv.2603.27682,
title = {Cs$_3$V$_9$Te$_{13}$: A Correlated Electron System with Topological Flat Bands},
author = {Chang-Chao Liu and Ji-Yong Liu and Jing Li and Hua-Xun Li and Jia-Yi Lu and Tong Shi and Qing-Xin Dong and Gen Li and Bo-Sen Wang and Yi Liu and Jin-Guang Cheng and Guang-Han Cao},
journal= {arXiv preprint arXiv:2603.27682},
year = {2026}
}