Isotropic Nature of the Metallic Kagome Ferromagnet Fe 3 Sn 2 at High Temperatures.

Anisotropy and competing exchange interactions have emerged as two central ingredients needed for centrosymmetric materials to exhibit topological spin textures. Fe 3 Sn 2 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 Fe 3 Sn 2 is an isotropic ferromagnet below T C ≈ 660 K to at least 480 K—the lower temperature threshold of our experimental configuration. Fe 3 Sn 2 is known to have competing magnetic exchange interactions, correlated electron behavior, weak magnetocrystalline anisotropy, and lattice (spatial) anisotropy; all of these features are thought to play a role in stabilizing skyrmions in centrosymmetric systems. Our results reveal that at the elevated temperatures measured, there is an absence of significant magnetocrystalline anisotropy and that the system behaves as a nearly ideal isotropic exchange interaction ferromagnet, with a spin stiffness D (T = 480 K ) = 168 meV Å 2 , which extrapolates to a ground state spin stiffness D (T = 0 K ) = 231 meV Å 2 . [ABSTRACT FROM AUTHOR]