CC BY 4.0 UnportedHan, MinyongInoue, HisashiFang, ShiangJohn, CaolanYe, LindaChan, Mun K.Graf, DavidSuzuki, TakehitoGhimire, Madhav PrasadCho, Won JoonKaxiras, EfthimiosCheckelsky, Joseph G.2021-12-032021-12-032021https://oa.tib.eu/renate/handle/123456789/7630https://doi.org/10.34657/6677The kagome lattice has long been regarded as a theoretical framework that connects lattice geometry to unusual singularities in electronic structure. Transition metal kagome compounds have been recently identified as a promising material platform to investigate the long-sought electronic flat band. Here we report the signature of a two-dimensional flat band at the surface of antiferromagnetic kagome metal FeSn by means of planar tunneling spectroscopy. Employing a Schottky heterointerface of FeSn and an n-type semiconductor Nb-doped SrTiO3, we observe an anomalous enhancement in tunneling conductance within a finite energy range of FeSn. Our first-principles calculations show this is consistent with a spin-polarized flat band localized at the ferromagnetic kagome layer at the Schottky interface. The spectroscopic capability to characterize the electronic structure of a kagome compound at a thin film heterointerface will provide a unique opportunity to probe flat band induced phenomena in an energy-resolved fashion with simultaneous electrical tuning of its properties. Furthermore, the exotic surface state discussed herein is expected to manifest as peculiar spin-orbit torque signals in heterostructure-based spintronic devices.enghttps://creativecommons.org/licenses/by/4.0/500Electronic properties and materialsSurfaces, interfaces and thin filmsTopological insulatorsArticle