High field quantum oscillation studies of Dirac electrons in iron-based kagome lattice metals*

The kagome lattice has long been theoretically known to harbor Dirac dispersions together with a dispersionless (flat) band. The relevance of the kagome lattice model in the context of electronic structures has recently been established in a class of binary hexagonal iron stannides, where Dirac dispersions derived from Fe 3d electrons are observed at Brillouin zone corners in photoemission studies [1,2]. Here we report high magnetic field quantum oscillation studies of Dirac electrons in these iron-based kagome metals including ferromagnetic Fe₃Sn₂ [3] and antiferromagnetic FeSn [2]. In Fe₃Sn₂ we observe a doublet of quasi-2D bulk Dirac electrons while a single bulk Dirac pocket is identified in FeSn. We further discuss the impact of crystallographic stacking and magnetic order on the Dirac electronic states in Fe₃Sn₂ and FeSn. References: [1] L. Ye, M. Kang et al., Nature 555 638-642 (2018). [2] M. Kang, L. Ye et al., arXiv/1906.02167, Nat. Mater. (in press). [3] L. Ye et al., Nat. Comm. 10, 4870 (2019).