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Published March 29, 2018 | v1
Journal Article Open

Massive Dirac fermions in a ferromagnetic kagome metal

Ye, Linda ORCID icon
Kang, Mingu
Liu, Junwei
von Cube, Felix
Wicker, Christina R.
Suzuki, Takehito ORCID icon
Jozwiak, Chris ORCID icon
Bostwick, Aaron ORCID icon
Rotenberg, Eli ORCID icon
Bell, David C. ORCID icon
Fu, Liang
Comin, Riccardo ORCID icon
Checkelsky, Joseph G. ORCID icon

Abstract

The kagome lattice is a two-dimensional network of corner-sharing triangles that is known to host exotic quantum magnetic states. Theoretical work has predicted that kagome lattices may also host Dirac electronic states that could lead to topological and Chern insulating phases, but these states have so far not been detected in experiments. Here we study the d-electron kagome metal Fe₃Sn₂, which is designed to support bulk massive Dirac fermions in the presence of ferromagnetic order. We observe a temperature-independent intrinsic anomalous Hall conductivity that persists above room temperature, which is suggestive of prominent Berry curvature from the time-reversal-symmetry-breaking electronic bands of the kagome plane. Using angle-resolved photoemission spectroscopy, we observe a pair of quasi-two-dimensional Dirac cones near the Fermi level with a mass gap of 30 millielectronvolts, which correspond to massive Dirac fermions that generate Berry-curvature-induced Hall conductivity. We show that this behaviour is a consequence of the underlying symmetry properties of the bilayer kagome lattice in the ferromagnetic state and the atomic spin–orbit coupling. This work provides evidence for a ferromagnetic kagome metal and an example of emergent topological electronic properties in a correlated electron system. Our results provide insight into the recent discoveries of exotic electronic behaviour in kagome-lattice antiferromagnets and may enable lattice-model realizations of fractional topological quantum states.

Copyright and License

© 2018 Macmillan Publishers Limited.

Acknowledgement

We are grateful to X.-G. Wen and E. Tang for discussions.

Funding

This research was funded in part by the Gordon and Betty Moore Foundation EPiQS Initiative, grant GBMF3848 to J.G.C. and NSF grant DMR-1554891. L.Y., J.L. and F.v.C. acknowledge support by the STC Center for Integrated Quantum Materials, NSF grant number DMR-1231319. L.Y. acknowledges support by the Tsinghua Education Foundation. M.K. acknowledges a Samsung Scholarship from the Samsung Foundation of Culture. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract number DE-AC02-05CH11231. A portion of this work was performed at the National High Magnetic Field Laboratory, which is supported by NSF cooperative agreement number DMR-1157490, the State of Florida and the US Department of Energy.

Contributions

Linda Ye and Mingu Kang: These authors contributed equally to this work. 

L.Y., T.S. and C.R.W. grew the single crystals. L.Y. characterized the materials, performed the transport and magnetic measurements and analysed the resultant data. M.K., C.J., A.B. and E.R. performed the ARPES experiment and analysed the resultant data. J.L. and L.Y. performed the theoretical calculations. F.v.C. and D.C.B. performed the electron microscopy study. All authors contributed to writing the manuscript. L.F., R.C. and J.G.C. supervised the project.

Data Availability

The data that support the findings of this study are available from the corresponding authors on reasonable request.

Conflict of Interest

The authors declare no competing financial interests.

Files

Extended Data Figure 5_ Berry curvature and Hall conductivity for a massive Dirac fermion. _ Nature.pdf

Additional details

Identifiers Funding
Created:
October 24, 2023
Modified:
October 24, 2023