Magnetodynamic properties of ultrathin films of Fe $$_{\textbf{3}}$$ Sn $$_{\textbf{2}}$$ -a topological kagome ferromagnet

Fe $$_3$$ Sn $$_{2}$$ is a topological kagome ferromagnet that possesses numerous Weyl points close to the Fermi energy, which can manifest various unique transport phenomena such as chiral anomaly, anomalous Hall effect, and giant magnetoresistance. However, the magnetodynamic properties of Fe $$_3$$ Sn $$_{2}$$ have not yet been explored. Here, we report, for the first time, the measurements of the intrinsic Gilbert damping constant ( $$\alpha _\text{int}$$ ), and the effective spin mixing conductance (g $$_\text{eff}^{\uparrow \downarrow }$$ ) of Pt/Fe $$_3$$ Sn $$_2$$ bilayers for Fe $$_3$$ Sn $$_{2}$$ thicknesses down to 2 nm, for which $$\alpha _\text{int}$$ is $$(3.8 \pm 0.2) \times 10^{-2}$$ , and g $$_\text{eff}^{\uparrow \downarrow }$$ is $$(11.7 \pm 0.6)~\text{nm}^{-2}$$ . The films have a high saturation magnetization, $$M_\text{S}=620~\mathrm{emu~cm^{-3}}$$ , and large anomalous Hall coefficient, $$R_\text{S}=4.6\times 10^{-10}~{\Omega ~\rm cm~G^{-1}}$$ . The large values of g $$_\text{eff}^{\uparrow \downarrow }$$ , together with the topological properties of Fe $$_3$$ Sn $$_2$$ , make Fe $$_3$$ Sn $$_2$$ /Pt bilayers useful heterostructures for the study of topological spintronic devices.