Epitaxy growth of atomically smooth kagome metal film

The two-dimensional kagome lattice is a well-known platform for exploring the interplay of topology, electron correlations, and magnetism. Significantly, the antiferromagnetic kagome metal FeSn, composed of alternating Fe₃Sn-Sn₂ layers, was found to host Dirac fermions and flat bands on the bulk crystal, owing to a comparably weak coupling between the Fe₃Sn kagome planes (1). However, the cleaved crystals often exhibit small Fe₃Sn and Sn₂ terminated terraces with a rather large defect density (2). This limits their suitability for the study with surface-sensitive probes

Using molecular beam epitaxy (MBE), we have explored the growth process of the prototypical kagome metal FeSn on the STO(111) surface. Varying the growth process parameters, we have realized atomically smooth and defect-free FeSn films and islands. Our in-situ scanning tunneling microscopy and ex-situ electronic transport measurements demonstrate the high quality of the FeSn films. Making use of the precise growth control of MBE, we will further present our recent results on the stoichiometric doping and layer-by-layer growth of FeSn and its related compounds. Realizing atomically flat kagome metal films and islands down to the ultra-thin limit, our work provides avenues to study topological and correlated electronic states in kagome metals and heterostructures with the STM and electric transport measurements.