Large ordered moment with strong easy-plane anisotropy and vortex-domain pattern in the kagome ferromagnet Fe3Sn

Abstract

We report the magnetic anisotropy of kagome bilayer ferromagnet Fe3Sn probed by the bulk magnetometry and magnetic force microscopy (MFM) on high-quality single crystals. The dependence of magnetization on the orientation of the external magnetic field reveals strong easy-plane magnetocrystalline anisotropy and anisotropy of the saturation magnetization. The leading magnetocrystalline anisotropy constant shows a monotonous increase from K 1 ≈ − 1.0 × 10 6 J / m 3 at 300 K to − 1.3 × 10 6 J / m 3 at 2 K. Our ab initio electronic structure calculations yield the value of total magnetic moment of 7.1 μ B / f . u . and a magnetocrystalline anisotropy energy density of −0.57 meV / f . u . ( − 1.62 × 10 6 J / m 3 ) both being in reasonable agreement with the experimental values. The MFM imaging reveals micrometer-scale magnetic vortices with weakly pinned cores that vanish at the saturation field of ∼3 T applied perpendicular to the kagome plane. The observed vortex-domain structure is well reproduced by the micromagnetic simulations, using the experimentally determined value of the anisotropy and exchange stiffness.