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Magnetism and charge density wave order in kagome FeGe

Nature Physics volume 19, pages 814–822 (2023)Cite this article

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Abstract

Electron correlations often lead to emergent orders in quantum materials, and one example is the kagome lattice materials where topological states exist in the presence of strong correlations between electrons. This arises from the features of the electronic band structure that are associated with the kagome lattice geometry: flat bands induced by destructive interference of the electronic wavefunctions, topological Dirac crossings and a pair of van Hove singularities. Various correlated electronic phases have been discovered in kagome lattice materials, including magnetism, charge density waves, nematicity and superconductivity. Recently, a charge density wave was discovered in the magnetic kagome FeGe, providing a platform for understanding the interplay between charge order and magnetism in kagome materials. Here we observe all three electronic signatures of the kagome lattice in FeGe using angle-resolved photoemission spectroscopy. The presence of van Hove singularities near the Fermi level is driven by the underlying magnetic exchange splitting. Furthermore, we show spectral evidence for the charge density wave as gaps near the Fermi level. Our observations point to the magnetic interaction-driven band modification resulting in the formation of the charge density wave and indicate an intertwined connection between the emergent magnetism and charge order in this moderately correlated kagome metal.

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Fig. 1: Crystal structure and electronic structure.
Fig. 2: Key signatures of kagome band structure.
Fig. 3: Temperature evolution of VHS.
Fig. 4: Observation of CDW gap.
Fig. 5: Electron–boson coupling in FeGe.

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Source data are provided with this paper. All other data that support the findings of this study are available from the corresponding authors upon reasonable request.

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The band structure and phonon calculations used in this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

We thank J. Zhu, C. Lane, Q. Si and C. Setty for helpful discussions. The ARPES work is supported by the Gordon and Betty Moore Foundation’s EPiQS Initiative through grant no. GBMF9470 (M.Y.), Robert A. Welch Foundation grant no. C-2024 (M.Y.) and U.S. Department of Energy (DOE) grant bo. DE-SC0021421 (M.Y.). The neutron scattering and single-crystal synthesis work at Rice was supported by US NSF-DMR-2100741 (P.D.) and by the Robert A. Welch Foundation under grant no. C-1839 (P.D.), respectively. The work at the University of California, Berkeley was supported by the U.S. DOE under contract no. DE-AC02-05-CH11231 within the Quantum Materials Program (KC2202) (R.J.B.). This research used resources of the Advanced Light Source and the Stanford Synchrotron Radiation Lightsource, both U.S. DOE Office of Science User Facilities under contract nos. DE-AC02-05CH11231 and AC02-76SF00515, respectively. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by ORNL. B.Y. acknowledges financial support from the European Research Council (ERC Consolidator grant “NonlinearTopo”, no. 815869) and an ISF personal research grant (no. 2932/21). JSO acknowledges the support of the NSF Grants Nos. DMR-1921798 and DMR-1921847.

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Author notes

  1. These authors contributed equally: Xiaokun Teng, Ji Seop Oh.

Authors and Affiliations

  1. Department of Physics and Astronomy, Rice University, Houston, TX, USA

    Xiaokun Teng, Ji Seop Oh, Lebing Chen, Jianwei Huang, Bin Gao, Pengcheng Dai & Ming Yi

  2. Department of Physics, University of California, Berkeley, CA, USA

    Ji Seop Oh & Robert J. Birgeneau

  3. Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot, Israel

    Hengxin Tan & Binghai Yan

  4. Department of Physics, Southern University of Science and Technology, Shenzhen, China

    Jia-Xin Yin

  5. Department of Physics, University of Washington, Seattle, WA, USA

    Jiun-Haw Chu

  6. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, USA

    Makoto Hashimoto & Donghui Lu

  7. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Chris Jozwiak, Aaron Bostwick & Eli Rotenberg

  8. Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA

    Garrett E. Granroth

  9. Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

    Robert J. Birgeneau

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Contributions

M.Y., P.D. and R.J.B. managed the project. The single-crystal FeGe samples were grown by X.T. and B.G. under the guidance of P.D. APRES experiments were carried out by J.S.O., X.T., J.H. and M.Y. with the assistance of M.H., D.L., C.J., A.B. and E.R. First-principles calculations were performed by H.T. and B.Y. Neutron scattering measurements and analysis were carried out by G.G., X.T., L.C. and P.D. The paper was written by M.Y., P.D., X.T., J.S.O. and L.C. with input from and significant discussions with all co-authors.

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Correspondence to Robert J. Birgeneau, Pengcheng Dai or Ming Yi.

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Supplementary Information

Supplementary Figs. S1–S11 and Sections 1–8.

Source data

Source Data Fig. 1

DFT calculations and script to extract spin-resolved calculations.

Source Data Fig. 3

Raw data for Fig. 3b–d,f–h.

Source Data Fig. 4

Raw data for Fig. 4g,h,j,l.

Source Data Fig. 5

Raw data for Fig. 5b–d and fitted data for Fig. 5h,i.

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Teng, X., Oh, J.S., Tan, H. et al. Magnetism and charge density wave order in kagome FeGe. Nat. Phys. 19, 814–822 (2023). https://doi.org/10.1038/s41567-023-01985-w

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