Isotropic Nature of the Metallic Kagome Ferromagnet Fe₃Sn₂ at High Temperatures

Anisotropy and competing exchange interactions have emerged as two central ingredients needed for centrosymmetric materials to exhibit topological spin textures. Fe₃Sn₂ is thought to have these ingredients as well, as it has recently been discovered to host room temperature skyrmionic bubbles with an accompanying topological Hall effect. We present small-angle inelastic neutron scattering measurements that unambiguously show that Fe₃Sn₂ is an isotropic ferromagnet below $T_C\approx 660\hspace{0.17em}\hspace{0.17em}\text{K}$ to at least 480 K - the lower temperature threshold of our experimental configuration. Fe₃Sn₂ is known to have competing magnetic exchange interactions, correlated electron behavior, weak magnetocrystalline anisotropy, and lattice anisotropy; all of these features are thought to play a role in stabilizing skyrmions in centrosymmetric systems. Our results reveal that at elevated temperatures, there is an absence of magnetocrystalline anisotropy and that the system behaves as a typical exchange ferromagnet with a spin stiffness $D\left(T=0\hspace{0.17em}\text{K}\right)=271\pm 9\hspace{0.17em}\text{meV}\hspace{0.17em}\hspace{0.17em}{\text{Å}}^2$.