Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Dirac fermions and flat bands in the ideal kagome metal FeSn


A kagome lattice of 3d transition metal ions is a versatile platform for correlated topological phases hosting symmetry-protected electronic excitations and magnetic ground states. However, the paradigmatic states of the idealized two-dimensional kagome lattice—Dirac fermions and flat bands—have not been simultaneously observed. Here, we use angle-resolved photoemission spectroscopy and de Haas–van Alphen quantum oscillations to reveal coexisting surface and bulk Dirac fermions as well as flat bands in the antiferromagnetic kagome metal FeSn, which has spatially decoupled kagome planes. Our band structure calculations and matrix element simulations demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals, and evidence that the coexisting Dirac surface state realizes a rare example of fully spin-polarized two-dimensional Dirac fermions due to spin-layer locking in FeSn. The prospect to harness these prototypical excitations in a kagome lattice is a frontier of great promise at the confluence of topology, magnetism and strongly correlated physics.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Crystal structure of binary kagome metals.
Fig. 2: Photoemission experiments on FeSn.
Fig. 3: Magneto-quantum oscillations and slab DFT calculations of FeSn.
Fig. 4: Signature of flat bands in FeSn.

Data availability

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

Code availability

The codes used for the DFT and tight-binding calculations in this study are available from the corresponding authors upon reasonable request.


  1. 1.

    Sachdev, S. Kagome- and triangular-lattice Heisenberg antiferromagnets: ordering from quantum fiuctuations and quantum-disordered ground states with unconfined bosonic spinons. Phys. Rev. B 45, 12377–12396 (1992).

    CAS  Article  Google Scholar 

  2. 2.

    Balents, L. Spin liquids in frustrated magnets. Nature 464, 199–208 (2010).

    CAS  Article  Google Scholar 

  3. 3.

    Guo, H. M. & Franz, M. Topological insulator on the kagome lattice. Phys. Rev. B 80, 113102 (2009).

    Article  Google Scholar 

  4. 4.

    Mazin, I. I. et al. Theoretical prediction of a strongly correlated Dirac metal. Nat. Commun. 5, 4261 (2014).

    CAS  Article  Google Scholar 

  5. 5.

    Xu, G., Lian, B. & Zhang, S.-C. Intrinsic quantum anomalous Hall effect in the kagome lattice Cs2LiMn3F12. Phys. Rev. Lett. 115, 186802 (2015).

    Article  Google Scholar 

  6. 6.

    Chen, H., Niu, Q. & Macdonald, A. H. Anomalous hall effect arising from noncollinear antiferromagnetism. Phys. Rev. Lett. 112, 17205 (2014).

    Article  Google Scholar 

  7. 7.

    Kübler, J. & Felser, C. Non-collinear antiferromagnets and the anomalous Hall effect. Europhys. Lett. 108, 67001 (2014).

    Article  Google Scholar 

  8. 8.

    Tang, E., Mei, J.-W. & Wen, X.-G. High-temperature fractional quantum Hall states. Phys. Rev. Lett. 106, 236802 (2011).

    Article  Google Scholar 

  9. 9.

    Burkov, A. A. & Balents, L. Weyl semimetal in a topological insulator multilayer. Phys. Rev. Lett. 107, 127205 (2011).

    CAS  Article  Google Scholar 

  10. 10.

    Wen, J., Rüegg, A., Wang, C. C. J. & Fiete, G. A. Interaction-driven topological insulators on the kagome and the decorated honeycomb lattices. Phys. Rev. B 82, 75125 (2010).

    Article  Google Scholar 

  11. 11.

    Bolens, A. & Nagaosa, N. Topological states on the breathing kagome lattice. Phys. Rev. B 99, 165141 (2019).

    CAS  Article  Google Scholar 

  12. 12.

    Nakatsuji, S., Kiyohara, N. & Higo, T. Large anomalous Hall effect in a non-collinear antiferromagnet at room temperature. Nature 527, 212–215 (2015).

    CAS  Article  Google Scholar 

  13. 13.

    Nayak, A. K. et al. Large anomalous Hall effect driven by non-vanishing Berry curvature in non-collinear antiferromagnet Mn3Ge. Sci. Adv. 2, e1501870 (2016).

    Article  Google Scholar 

  14. 14.

    Kuroda, K. et al. Evidence for magnetic Weyl fermions in a correlated metal. Nat. Mater. 16, 1090–1095 (2017).

    CAS  Article  Google Scholar 

  15. 15.

    Liu, Z. Q. et al. Electrical switching of the topological anomalous Hall effect in a non-collinear antiferromagnet above room temperature. Nat. Electron. 1, 172–177 (2018).

    CAS  Article  Google Scholar 

  16. 16.

    Ye, L. et al. Massive Dirac fermions in a ferromagnetic kagome metal. Nature 555, 638–642 (2018).

    CAS  Article  Google Scholar 

  17. 17.

    Yin, J. X. et al. Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet. Nature 562, 91–95 (2018).

    CAS  Article  Google Scholar 

  18. 18.

    Ye, L. et al. De Haas–van Alphen effect of correlated Dirac states in kagome metal Fe3Sn2. Nat. Commun. 10, 4870 (2019).

    Article  Google Scholar 

  19. 19.

    Lin, Z. et al. Flatbands and emergent ferromagnetic ordering in Fe3Sn2 kagome lattices. Phys. Rev. Lett. 121, 96401 (2018).

    Article  Google Scholar 

  20. 20.

    Liu, E. et al. Giant anomalous Hall effect in a ferromagnetic kagome-lattice semimetal. Nat. Phys. 14, 1125–1131 (2018).

    CAS  Article  Google Scholar 

  21. 21.

    Wang, Q. et al. Large intrinsic anomalous Hall effect in half-metallic ferromagnet Co3Sn2S2 with magnetic Weyl fermions. Nat. Commun. 9, 3681 (2018).

    Article  Google Scholar 

  22. 22.

    Ghimire, M. P. et al. Creating Weyl nodes and controlling their energy by magnetization rotation. Preprint at (2019).

  23. 23.

    Yin, J.-X. et al. Negative flat band magnetism in a spin–orbit-coupled correlated kagome magnet. Nat. Phys. 15, 443–448 (2019).

    CAS  Article  Google Scholar 

  24. 24.

    Hartmann, O. & Wappling, R. Muon spin precession in the hexagonal antiferromagnet FeSn. Phys. Scr. 35, 499–503 (1987).

    CAS  Article  Google Scholar 

  25. 25.

    Richard, P. et al. Observation of Dirac cone electronic dispersion in BaFe2As2. Phys. Rev. Lett. 104, 137001 (2010).

    CAS  Article  Google Scholar 

  26. 26.

    Tan, S. Y. et al. Observation of Dirac cone band dispersions in FeSe thin films by photoemission spectroscopy. Phys. Rev. B 93, 104513 (2016).

    Article  Google Scholar 

  27. 27.

    Zhang, P. et al. Observation of topological superconductivity in iron-based superconductor. Science 360, 182–186 (2018).

    Article  Google Scholar 

  28. 28.

    Chiang, T. Photoemission studies of quantum well states in thin films. Surf. Sci. Rep. 39, 181–235 (2000).

    CAS  Article  Google Scholar 

  29. 29.

    Moser, S. et al. Tunable polaronic conduction in anatase TiO2. Phys. Rev. Lett. 110, 196403 (2013).

    CAS  Article  Google Scholar 

  30. 30.

    Ohta, T., Bostwick, A., Seyller, T., Horn, K. & Rotenberg, E. Controlling the electronic structure of bilayer graphene. Science 313, 951–954 (2006).

    CAS  Article  Google Scholar 

  31. 31.

    Zhou, S. Y. et al. First direct observation of Dirac fermions in graphite. Nat. Phys. 2, 595–599 (2006).

    CAS  Article  Google Scholar 

  32. 32.

    Marchenko, D. et al. Highly spin-polarized Dirac fermions at the graphene/Co interface. Phys. Rev. B 91, 235431 (2015).

    Article  Google Scholar 

  33. 33.

    Sun, Q. F., Jiang, Z. T., Yu, Y. & Xie, X. C. Spin superconductor in ferromagnetic graphene. Phys. Rev. B 84, 214501 (2011).

    Article  Google Scholar 

  34. 34.

    Wang, Y. H. et al. Observation of a warped helical spin texture in Bi2Se3 from circular dichroism angle-resolved photoemission spectroscopy. Phys. Rev. Lett. 107, 207602 (2011).

    CAS  Article  Google Scholar 

  35. 35.

    Hwang, C. et al. Direct measurement of quantum phases in graphene via photoemission spectroscopy. Phys. Rev. B 84, 125422 (2011).

    Article  Google Scholar 

  36. 36.

    Liu, Y., Bian, G., Miller, T. & Chiang, T. C. Visualizing electronic chirality and Berry phases in graphene systems using photoemission with circularly polarized light. Phys. Rev. Lett. 107, 166803 (2011).

    CAS  Article  Google Scholar 

  37. 37.

    Neupert, T., Santos, L., Chamon, C. & Mudry, C. Fractional quantum Hall states at zero magnetic field. Phys. Rev. Lett. 106, 236804 (2011).

    Article  Google Scholar 

  38. 38.

    Sun, K., Gu, Z., Katsura, H. & Das Sarma, S. Nearly flatbands with nontrivial topology. Phys. Rev. Lett. 106, 236803 (2011).

    Article  Google Scholar 

  39. 39.

    Patil, S. et al. ARPES view on surface and bulk hybridization phenomena in the antiferromagnetic Kondo lattice CeRh2Si2. Nat. Commun. 7, 11029 (2016).

    CAS  Article  Google Scholar 

  40. 40.

    Cao, Y. et al. Correlated insulator behaviour at half-filling in magic-angle graphene superlattices. Nature 556, 80–84 (2018).

    CAS  Article  Google Scholar 

  41. 41.

    Koepernik, K. & Eschrig, H. Full-potential nonorthogonal local-orbital minimum-basis band-structure scheme. Phys. Rev. B 59, 1743–1757 (1999).

    CAS  Article  Google Scholar 

  42. 42.

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

    CAS  Google Scholar 

  43. 43.

    Koepernik, K. FPLO (IFW Dresden, 2018).

Download references


We are grateful to C. Felser, S. Borisenko, M. Knupfer, K. Koepernik, L. Levitov and A. Fahimniya for fruitful discussions. M.P.G., J.-S.Y., J.I.F., S.F., M.R. and J.v.d.B. thank U. Nitzsche for technical assistance in maintaining computing resources at IFW Dresden. R.C. acknowledges support from the Alfred P. Sloan Foundation. This research was funded, in part, by the Gordon and Betty Moore Foundation EPiQS Initiative, Grant no. GBMF3848 to J.G.C. and ARO Grant no. W911NF-16-1-0034. M.K., L.Y., S.F., E.K. and M.P.G. acknowledge support by the STC Center for Integrated Quantum Materials, NSF grant number DMR-1231319. M.K. acknowledges support from the Samsung Scholarship from the Samsung Foundation of Culture. L.Y. acknowledges support from the Tsinghua Ed fucation Foundation. The computations in this paper were run on the ITF/IFW computer clusters (Dresden, Germany) and Odyssey cluster supported by the FAS Division of Science, Research Computing Group at Harvard University. M.R and J.v.d.B. acknowledge support from the German Research Foundation (DFG) via SFB 1143, project A5. M.P.G. thanks the Alexander von Humboldt Foundation for financial support through the Georg Forster Research Fellowship Program, Germany. J.-S.Y. and J.I.F. thank the IFW excellence programme. This research used the resources of the Advanced Light Source, a US Department of Energy (DOE) Office of Science User Facility under contract no. DE-AC02-05CH11231. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by the National Science Foundation Cooperative Agreement no. DMR-1644779, the State of Florida and the DOE. Pulsed magnetic field measurements were supported by the DOE BES ‘Science at 100 T’ grant. Operation of the ESM beamline at the National Synchrotron Light Source is supported by DOE Office of Science User Facility Program operated for the DOE Office of Science by Brookhaven National Laboratory under Contract no. DE-AC02-98CH10886. D.C.B. acknowledges use of the Center for Nanoscale Systems, a member of the National Nanotechnology Coordinated Infrastructure Network, which is supported by the National Science Foundation under NSF award no. 1541959. J.v.d.B. was supported by the DFG through the Wurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter - ct.qmat (EXC 2147, project ID 39085490).

Author information




M.K. performed the ARPES experiment and analysed the resulting data while A.L., C.J., A.B., E.R., K.K. and E.V. assisted. L.Y. synthesized and characterized the single crystals and performed the quantum oscillation experiments while M.K.C., R.D.M. and D.G. assisted. M.P.G. and S.F. performed the theoretical calculations while J.-S.Y., J.I.F. J.v.d.V., M.R. and E.K. assisted. M.H. and M.K. conducted the AFM measurements. D.C.B. performed the electron microscopy study. All authors contributed to writing the manuscript. J.G.C. and R.C. supervised the project.

Corresponding authors

Correspondence to Joseph G. Checkelsky or Riccardo Comin.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figures 1–17, Notes 1–9, refs. 1–10.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Kang, M., Ye, L., Fang, S. et al. Dirac fermions and flat bands in the ideal kagome metal FeSn. Nat. Mater. 19, 163–169 (2020).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing