Intrinsic anomalous Hall response in the bilayer kagome ferromagnet Co${}_3$Sn

Abstract

Transition-metal kagome magnets provide a rich platform for investigating the interplay between layer stacking, magnetic order, and band topology. Here, we report the molecular beam epitaxy and experimental investigation of high-quality thin films of the kagome metal Co${}_3$Sn, which has not been synthesized in bulk form yet. Structural and chemical analyses confirm a hexagonal lattice structure ($P{6}_3/mmc$) composed of direct A-B stacked Co${}_3$Sn kagome bilayers. Magnetometry reveals robust easy-plane ferromagnetism with a Curie temperature exceeding $300\text{K}$. Magneto-transport measurements demonstrate metallic behavior (carrier density $n\approx 5.01\times 10^{22}{\text{cm}}^{-3}$) alongside a temperature-independent anomalous Hall conductivity of ${\sigma }_{\mathrm{AHE}}\approx 90{\Omega }^{-1}\cdot {\mathrm{cm}}^{-1}$, extending from $2\text{K}$ up to room temperature. Results from first-principles density functional theory calculations attribute this anomalous Hall response to intrinsic Berry curvature hotspots near the Fermi level in the spin-split band structure. Our results establish Co${}_3$Sn as a room-temperature kagome ferromagnet and highlight the impact of the layer stacking sequence on the material properties of kagome metals from the CoSn family.