Magnetocrystalline anisotropy and volume ratio of FePt grains with c-axes parallel to the film plane in FePt granular film with various grain boundary materials

In this study, we analyzed the structure for FePt grains whose c-axes are parallel to the film plane (in-plane grains) and the effect of the grains on magnetic properties. According to the analysis for granular films with a constant GBM volume of 30 vol% deposited at a high substrate temperature, the structure such as the lattice constant c, a and degree of order for in-plane grains was estimated to be the same as that of FePt grains whose c-axes are normal to the film plane (normal grains). In addition, it was found that perpendicular magnetic anisotropy was dependent on both the ratio of in-plane grains to the normal grains (R_parallel) and the degree of order. Considering R_parallel and the volume of GBM, magnetocrystalline anisotropy (K_u^grain) is estimated to be 3.43 × 10⁷ (erg cm⁻³) for perfect ordering FePt grains.