Magnetic Anisotropy of Sm(Fe-Co-Ni)<sub>12</sub>-B Thin Films and Formation of ThMn<sub>12</sub> Phase by Element Substitution and Addition

The combined addition of Ni and Co is a promising method for stabilizing the ThMn12-type crystal structure without significantly decreasing the saturation magnetization. In this work, the structure and magnetic properties of Sm(Fe-Co)12-B thin films by substituting Ni and Co with a part of Fe sites and adding B were investigated in detail. It was observed that when the Fe sites of Sm(Fe-Co-Ni)12 thin films were partially substituted with Ni, the peak intensity from the ThMn12-type phase decreased, but recovered with increasing the amount of Co substitution. Furthermore, most of the samples with combined Ni and Co substitution had an isotropic or in-plane easy axis of magnetization with respect to the film plane. However, it was confirmed that the easy axis of magnetization was varied to the perpendicular direction by adding a small amount of B to the Sm(Fe-Co-Ni)12 thin films.