Atomic Layer Molecular Beam Epitaxy of Kagome Magnet RMn$_6$Sn$_6$ (R = Er, Tb) Thin Films

Kagome lattices have garnered substantial interest because their bandstructure consists of topological flat bands and Dirac cones. The RMn$_6$Sn$_6$(R = rare earth) compounds are particularly interesting because of theexistence of large intrinsic anomalous Hall effect (AHE) which originates fromthe gapped Dirac cones near the Fermi level. This makes RMn$_6$Sn$_6$ anoutstanding candidate for realizing the high-temperature quantum anomalous Halleffect. The growth of RMn$_6$Sn$_6$ thin films is beneficial for bothfundamental research and potential applications. However, most of the studieson RMn$_6$Sn$_6$ have focused on bulk crystals so far, and the synthesis ofRMn$_6$Sn$_6$ thin films has not been reported so far. Here we report theatomic layer molecular beam epitaxy growth, structural and magneticcharacterizations, and transport properties of ErMn$_6$Sn$_6$ andTbMn$_6$Sn$_6$ thin films. It is especially noteworthy that TbMn$_6$Sn$_6$ thinfilms have out-of-plane magnetic anisotropy, which is important for realizingthe quantum anomalous Hall effect. Our work paves the avenue toward the controlof the AHE using devices patterned from RMn$_6$Sn$_6$ thin films.