中国物理B ›› 2026, Vol. 35 ›› Issue (3): 36801-036801.doi: 10.1088/1674-1056/ae2f53

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Real-space imaging of kagome flat band localization in Fe3Sn2

Yifan Wang(汪逸凡)1,2,3, Lili Jiang(蒋利利)1,2,3, Qiang Zhang(张强)1,2,3, Zhiyong Lin(林志勇)1,2,3, Hui Zhang(张汇)1,2,3,†, and Changgan Zeng(曾长淦)1,2,3,‡   

  1. 1 CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei 230026, China;
    2 International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China;
    3 Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
  • 收稿日期:2025-09-29 修回日期:2025-12-12 接受日期:2025-12-19 出版日期:2026-02-11 发布日期:2026-03-03
  • 通讯作者: Hui Zhang, Changgan Zeng E-mail:huiz@ustc.edu.cn;cgzeng@ustc.edu.cn
  • 基金资助:
    Research and Development Program of China (Grant No. 2023YFA1406300), the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800), the National Natural Science Foundation of China (Grant Nos. 92165201, 12374458, 12488101, and 11974323), Anhui Provincial Key Research and Development Project (Grant No. 2023z04020008), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-046), the Fundamental Research Funds for the Central Universities (Grant No. WK9990000118), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB0510200).

Real-space imaging of kagome flat band localization in Fe3Sn2

Yifan Wang(汪逸凡)1,2,3, Lili Jiang(蒋利利)1,2,3, Qiang Zhang(张强)1,2,3, Zhiyong Lin(林志勇)1,2,3, Hui Zhang(张汇)1,2,3,†, and Changgan Zeng(曾长淦)1,2,3,‡   

  1. 1 CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, and Department of Physics, University of Science and Technology of China, Hefei 230026, China;
    2 International Center for Quantum Design of Functional Materials (ICQD), Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China;
    3 Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
  • Received:2025-09-29 Revised:2025-12-12 Accepted:2025-12-19 Online:2026-02-11 Published:2026-03-03
  • Contact: Hui Zhang, Changgan Zeng E-mail:huiz@ustc.edu.cn;cgzeng@ustc.edu.cn
  • Supported by:
    Research and Development Program of China (Grant No. 2023YFA1406300), the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302800), the National Natural Science Foundation of China (Grant Nos. 92165201, 12374458, 12488101, and 11974323), Anhui Provincial Key Research and Development Project (Grant No. 2023z04020008), the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-046), the Fundamental Research Funds for the Central Universities (Grant No. WK9990000118), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB0510200).

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摘要： In geometrically frustrated lattices, flat bands can arise from destructive quantum interference, providing an ideal platform for exploring strong electron correlations. However, direct real-space evidence of their predicted atomic-scale electron localization remains elusive. By employing scanning tunneling microscopy/spectroscopy, with a focus on quasiparticle interference imaging, we demonstrate unambiguous atomic-scale localization of flat band electrons in the kagome metal Fe$_{3}$Sn$_{2}$. Crucially, quasiparticle interference imaging reveals a complete suppression of scattering wavevectors and standing waves exclusively at the flat band energy, indicating the absence of long-range coherent propagation. This disappearance of the quasiparticle interference signal, attributable to the non-propagating wavefunctions inherent to the kagome flat band, directly confirms real-space electron localization. These findings resolve the microscopic link between quantum interference and localization of flat band electrons, paving the way for engineering correlated quantum states.

关键词: scanning tunneling microscopy, kagome, flat band, electron localization, quasiparticle interference

Abstract: In geometrically frustrated lattices, flat bands can arise from destructive quantum interference, providing an ideal platform for exploring strong electron correlations. However, direct real-space evidence of their predicted atomic-scale electron localization remains elusive. By employing scanning tunneling microscopy/spectroscopy, with a focus on quasiparticle interference imaging, we demonstrate unambiguous atomic-scale localization of flat band electrons in the kagome metal Fe$_{3}$Sn$_{2}$. Crucially, quasiparticle interference imaging reveals a complete suppression of scattering wavevectors and standing waves exclusively at the flat band energy, indicating the absence of long-range coherent propagation. This disappearance of the quasiparticle interference signal, attributable to the non-propagating wavefunctions inherent to the kagome flat band, directly confirms real-space electron localization. These findings resolve the microscopic link between quantum interference and localization of flat band electrons, paving the way for engineering correlated quantum states.

Key words: scanning tunneling microscopy, kagome, flat band, electron localization, quasiparticle interference

中图分类号:  (Microscopy of surfaces, interfaces, and thin films)

  • 68.37.-d
68.37.Ef (Scanning tunneling microscopy (including chemistry induced with STM)) 71.20.-b (Electron density of states and band structure of crystalline solids) 73.20.At (Surface states, band structure, electron density of states)