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  • Review Article
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Quantum states and intertwining phases in kagome materials

Nature Reviews Physics volume 5, pages 635–658 (2023)Cite this article

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Abstracts

In solid materials, non-trivial topological states, electron correlations and magnetism are central ingredients for realizing quantum properties, including unconventional superconductivity, charge and spin density waves and quantum spin liquids. The kagome lattice, made up of corner-sharing triangles, can host these three ingredients simultaneously and has proved to be a fertile platform for studying diverse quantum phenomena including those stemming from the interplay of these ingredients. This Review introduces the fundamental properties of the kagome lattice and discusses the complex phenomena observed in several materials systems, including the intertwining of charge order and superconductivity in some kagome metals, the modulation of magnetism and topology in some kagome magnets, and the combination of symmetry breaking and Mott physics in ‘breathing’ kagome insulators. The Review also highlights open questions in the field and future research directions in kagome systems.

Key points

  • The kagome lattice is formed by corner-sharing triangles, which can host Dirac points, van Hove singularities (vHSs) and flat bands.

  • The high Fermi surface instability around the vHSs and flat bands can give rise to various physical properties that can be entangled, including superconductivity, charge or spin orders, and complex magnetism.

  • Charge density wave (CDW) states induced by the vHSs mostly appear in kagome materials with non-magnetic or weak magnetism, but are rare in kagome magnets. The relationship between magnetism and CDWs is not yet fully understood.

  • Diverse magnetic properties appearing in kagome magnets are influenced by the interlayer and intralayer magnetic interaction of kagome lattices and other sublattices.

  • A Mott-insulating state was observed in the symmetry breaking, breathing kagome insulators with flat bands. Strong correlation physics related to flat bands can be studied in kagome system.

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Fig. 1: Lattice structure and electronic band property of kagome lattice.
Fig. 2: Lattice structure and electronic band structure of AV3Sb5.
Fig. 3: Representative physical properties of AV3Sb5.
Fig. 4: Crystal structures and physical properties in AM6X6 compounds.
Fig. 5: Crystal structure and physical properties of Nb3X8.

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Acknowledgements

Y.W. acknowledges support from NWO Talent Programme Veni financed by the Dutch Research Council (NWO), project no. VI.Veni.212.146. H.W. acknowledges support from the Kavli Institute of Nanoscience Delft Synergy grant 2022. Y.W., H.W. and M.N.A. acknowledge support from the Technical University of Delft Quantum Nanoscience Department as well as the Kavli Institute of Nanoscience Delft. J.Y.C. acknowledges NSF-DMR 2209804 and Welch AA-2056-20220101 for partial support of this work.

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  1. These authors contributed equally: Yaojia Wang, Heng Wu.

Authors and Affiliations

  1. Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands

    Yaojia Wang, Heng Wu & Mazhar N. Ali

  2. Department of Quantum Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, The Netherlands

    Yaojia Wang, Heng Wu & Mazhar N. Ali

  3. Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA

    Gregory T. McCandless & Julia Y. Chan

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Y.W. and H.W. wrote the majority of the manuscript. M.N.A. and J.Y.C. are the principal investigators. All authors contributed to the writing of the manuscript.

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Wang, Y., Wu, H., McCandless, G.T. et al. Quantum states and intertwining phases in kagome materials. Nat Rev Phys 5, 635–658 (2023). https://doi.org/10.1038/s42254-023-00635-7

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