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arXiv · 2508.08580

Emergent dynamical Kondo coherence and competing magnetic order in a correlated kagome flat-band metal CsCr6Sb6

Xiangqi Liu·Xuefeng Zhang·Jiachen Jiao·Renjie Zhang·Kaiwen Chen·Ying Wang·Yunguan Ye·Zhenhai Yu·Chengyu Jiang·Xia Wang·Lei Shu·Baiqing Lv·Gang Li·Yanfeng Guo
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Abstract

Correlated kagome metals host unique electronic states that enable exotic quantum phenomena. In the recently emerged CsCr6Sb6, these manifest through Kondo behavior from localized Cr-3d electrons and unprecedented band flattening near the Fermi level. Yet the intricate interplay among Kondo screening, magnetic frustration, and electronic correlations remains poorly understood-a fundamental gap we address through multifaceted experimental and theoretical approaches. Our angle-resolved photoemission spectroscopy measurements reveal electronic correlation-renormalized flat bands and muon spin relaxation study detect short-range magnetic order at TN ~ 80 K. Complementing these findings, density-functional theory and dynamical mean-field theory calculations identify a coherent-incoherent crossover at TN, with a remarkable restoration of coherence accompanying local moment suppression-an anomalous hallmark of Kondo behavior. Intriguingly, despite strong interlayer antiferromagnetic coupling, the system evades long-range magnetic order due to competing magnetic configurations separated by sub-meV energy differences. These insights establish CsCr6Sb6 as a prototypical platform for investigating dynamical Kondo screening in correlated flat-band systems, opening new avenues to study flat band physics and frustrated magnetism in correlated kagome lattices.

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Xiangqi Liu, Xuefeng Zhang, Jiachen Jiao, Renjie Zhang, Kaiwen Chen, Ying Wang, Yunguan Ye, Zhenhai Yu, Chengyu Jiang, Xia Wang, Lei Shu, Baiqing Lv, Gang Li, Yanfeng Guo. 2025-08-12. Emergent dynamical Kondo coherence and competing magnetic order in a correlated kagome flat-band metal CsCr6Sb6. https://doi.org/10.1103/f8b9-q54m

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