Spin excitations and flat electronic bands in a Cr-based kagome superconductor

In the quest for topology- and correlation-driven quantum states, kagome lattice materials have garnered significant interest for their band structures, featuring flat bands (FBs) from the quantum destructive interference of the electronic wavefunction. Tuning an FB to the chemical potential could induce electronic instabilities and emergent orders. Despite extensive studies, direct evidence of FBs tuned to the chemical potential and their role in emergent orders in bulk materials remains lacking. Using angle-resolved photoemission spectroscopy, resonant inelastic X-ray scattering, and density functional theory, we show that the low-energy structure of the Cr-based kagome metal superconductor CsCr<sub>3</sub>Sb<sub>5</sub> is dominated by FBs at the Fermi level. We also observe low-energy magnetic excitations evolving across the low-temperature transition, largely consistent with the FB shift. Our results suggest that the low-temperature order contains a magnetic origin and that the kagome FBs may play a role in the emergence of this order.

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Publication Details

Journal
Nature Communications
Published
2025-08-14
DOI
https://doi.org/10.1038/s41467-025-62298-5
Citations
8
Primary Topic
Advanced Condensed Matter Physics
Type
article
Field-Weighted Citation Impact
10.06

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article

Spin excitations and flat electronic bands in a Cr-based kagome superconductor

Boris I. Yakobson, Guang‐Han Cao, Ji Seop Oh, Pengcheng Dai et al.
8 citations
Nature Communications
Advanced Condensed Matter Physics
10.06
article

Spin excitations and flat electronic bands in a Cr-based kagome superconductor

Boris I. Yakobson, Guang‐Han Cao, Ji Seop Oh, Pengcheng Dai, Yuefei Huang, Chien‐Te Chen, Bin Gao, Eli Rotenberg, Ziqin Yue, J. Okamoto, D. J. Huang, Xingye Lu, Dong-Hui Lu, Yuan Fang, Chris M. Jozwiak, R. J. Birgeneau, Qimiao Si A, Aaron Bostwick, Yucheng Guo, Feng Ye, Cheng Hu, Makoto Hashimoto, Ming Yi, Junichiro Kono, H. Y. Huang, Atsushi Fujimori, Jiun‐Haw Chu, Zheng Ren, Yichen Zhang, Yiming Wang, Zhaoyu Liu, Zehao Wang, Fang Xie, Han Wu, Ananya Biswas, Ganesha Channagowdra
article en
8 citations

Abstract

In the quest for topology- and correlation-driven quantum states, kagome lattice materials have garnered significant interest for their band structures, featuring flat bands (FBs) from the quantum destructive interference of the electronic wavefunction. Tuning an FB to the chemical potential could induce electronic instabilities and emergent orders. Despite extensive studies, direct evidence of FBs tuned to the chemical potential and their role in emergent orders in bulk materials remains lacking. Using angle-resolved photoemission spectroscopy, resonant inelastic X-ray scattering, and density functional theory, we show that the low-energy structure of the Cr-based kagome metal superconductor CsCr<sub>3</sub>Sb<sub>5</sub> is dominated by FBs at the Fermi level. We also observe low-energy magnetic excitations evolving across the low-temperature transition, largely consistent with the FB shift. Our results suggest that the low-temperature order contains a magnetic origin and that the kagome FBs may play a role in the emergence of this order.

Nature CommunicationsVol. 16(1)
Oak Ridge National Laboratory (US), Lawrence Berkeley National Laboratory (US), National Yang Ming Chiao Tung University (TW), University of Washington (US), Beijing Normal University (CN), National Tsing Hua University (TW), SLAC National Accelerator Laboratory (US), Sookmyung Women's University (KR), National Synchrotron Radiation Research Center (TW), Stanford Synchrotron Radiation Lightsource (US), Rice University (US), The University of Tokyo (JP), Zhejiang University (CN), University of California, Berkeley (US)
National Science Foundation, U.S. Department of Energy, Gordon and Betty Moore Foundation, Rice University, National Science and Technology Council, Office of Science, Japan Society for the Promotion of Science, Office of Naval Research, Division of Materials Research, Basic Energy Sciences, Air Force Office of Scientific Research, Oak Ridge National Laboratory, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory, Division of Materials Sciences and Engineering
Openalex Percentile: Top 2%
Advanced Condensed Matter Physics
10.06
DOIOpen Access PDFOpenAlex
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