Electronic systems with flat bands are predicted to be a fertile ground for hosting emergent phenomena including unconventional magnetism and superconductivity1,2,3,4,5,6,7,8,9,10,11,12,13,14,15, but materials that manifest this feature are rare. Here, we use scanning tunnelling microscopy to elucidate the atomically resolved electronic states and their magnetic response in the kagome magnet Co3Sn2S2 (refs. 16,17,18,19,20). We observe a pronounced peak at the Fermi level, which we identify as arising from the kinetically frustrated kagome flat band. On increasing the magnetic field up to ±8 T, this state exhibits an anomalous magnetization-polarized many-body Zeeman shift, dominated by an orbital moment that is opposite to the field direction. Such negative magnetism is induced by spin–orbit-coupling quantum phase effects21,22,23,24,25 tied to non-trivial flat band systems. We image the flat band peak, resolve the associated negative magnetism and provide its connection to the Berry curvature field, showing that Co3Sn2S2 is a rare example of a kagome magnet where the low-energy physics can be dominated by the spin–orbit-coupled flat band.

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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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STM experimental and theoretical work at Princeton University was supported by the Gordon and Betty Moore Foundation (GBMF4547/M.Z.H.). ARPES characterization of the sample is supported by the United States Department of Energy (US DOE) under the Basic Energy Sciences programme (grant number DOE/BES DE-FG-02–05ER46200). Work at Renmin University was supported by the Ministry of Science and Technology of China (2016YFA0300504), the National Natural Science Foundation of China (nos. 11574394, 11774423 and 11822412), the Fundamental Research Funds for the Central Universities, and the Research Funds of Renmin University of China (15XNLF06, 15XNLQ07 and 18XNLG14). S.S.T. and T.N. acknowledge support from the European Union’s Horizon 2020 research and innovation programme (ERC-StG-Neupert-757867-PARATOP). Z.W. and K.J. acknowledge US DOE grant DE-FG02–99ER45747. We also acknowledge the Natural Science Foundation of China (grant nos. 11790313 and 11774007), the Key Research Program of the Chinese Academy of Sciences (grant no. XDPB08-1), the National Key R&D Program of China (grant nos. 2016YFA0300403 and 2018YFA035601), the Princeton Center for Theoretical Science and the Princeton Institute for the Science and Technology of Materials Imaging and Analysis Center at Princeton University. Muon spin rotation (µSR) experiments were performed at the πE3 beamline of the Paul Scherrer Institute, using the HAL-9500 µSR spectrometer. Z.G. acknowledges R. Scheuermann for support in the µSR experiments. M.Z.H. acknowledges support from Lawrence Berkeley National Laboratory and the Miller Institute of Basic Research in Science at the University of California, Berkeley in the form of a Visiting Miller Professorship.

Author information

Author notes

  1. These authors contributed equally: Jia-Xin Yin, Songtian S. Zhang, Guoqing Chang.


  1. Laboratory for Topological Quantum Matter and Advanced Spectroscopy (B7), Department of Physics, Princeton University, Princeton, NJ, USA

    • Jia-Xin Yin
    • , Songtian S. Zhang
    • , Guoqing Chang
    • , Zurab Guguchia
    • , Ilya Belopolski
    • , Nana Shumiya
    • , Daniel Multer
    • , Maksim Litskevich
    • , Tyler A. Cochran
    •  & M. Zahid Hasan
  2. Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, China

    • Qi Wang
    •  & Hechang Lei
  3. Department of Physics, University of Zurich, Zurich, Switzerland

    • Stepan S. Tsirkin
    •  & Titus Neupert
  4. Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, Villigen PSI, Switzerland

    • Zurab Guguchia
  5. Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, USA

    • Biao Lian
  6. International Center for Quantum Materials and School of Physics, Peking University, Beijing, China

    • Huibin Zhou
    •  & Shuang Jia
  7. CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing, China

    • Huibin Zhou
    •  & Shuang Jia
  8. Department of Physics, Boston College, Chestnut Hill, MA, USA

    • Kun Jiang
    •  & Ziqiang Wang
  9. Institute of Physics, Academia Sinica, Taipei, Taiwan

    • Hsin Lin
  10. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    • M. Zahid Hasan
  11. Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, NJ, USA

    • M. Zahid Hasan


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J.-X.Y. and S.S.Z. conducted the STM and STS experiments in consultation with M.Z.H.; Q.W., H.Lei, H.Z. and S.J. synthesized and characterized the sequence of samples; Z.G. performed µSR measurements in consultation with M.Z.H.; G.C., T.N., S.S.T., B.L., K.J., H.Lin and Z.W. carried out theoretical analysis in consultation with J.-X.Y. and M.Z.H.; I.B., N.S., D.M., M.L. and T.A.C. contributed to sample characterization and instrument calibration; J.-X.Y., S.S.Z. and M.Z.H. performed the data analysis and figure development and wrote the paper with contributions from all authors; M.Z.H. supervised the project. All authors discussed the results, interpretation and conclusion.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to M. Zahid Hasan.

Supplementary information

  1. Supplementary Information

    Supplementary Figures 1–7, additional theoretical details and Supplementary References 31–35.

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