Molecular beam epitaxy of Sn-based Kagome antiferromagnets

Binary compounds T_mX_n (T = Mn, Fe, Co; X = Sn, Ge; m:n = 3:1, 3:2, 1:1) have been shown to exhibit a plethora of interesting magnetotransport phenomena such as strong anisotropic anomalous Hall effect. Furthermore, when coupled with an adjacent ferromagnet, phenomena like spin Hall effects give rise to novel spin-orbit-torques. So far, film growth has mostly been achieved using magnetron sputtering by incorporating nonmagnetic buffer layers. Here we report the synthesis of ferromagnet/T_mX_n bilayer films: Fe/Mn₃Sn, Co/Mn₃Sn, Fe/FeSn and Co/FeSn using molecular beam epitaxy on insulating oxide substrates. Rutherford backscattering spectroscopy was used to confirm the stoichiometric window, where these phases are stabilized, while transport and magnetometry measurements were conducted to explore metallicity and magnetic ordering in the films. Structural characterization using high-resolution X-ray diffraction, reflection high-energy electron diffraction, and electron microscopy reveals the Mn₃Sn films grow as crystalline three-dimensional islands whereas FeSn films are flat and continuous, paving the way to integrate these materials into devices.