Increase in Coercivity of Sm(Fe-Co)-B Thin Films Due to Diffusion of Al Element from Cap Layer

The effects of Al diffusion and heat treatment on the structure and magnetic properties for Sm(Fe-Co)-B thin film have been investigated. In the X-ray diffraction patterns, peaks of (002) and (004) from ThMn12-type compounds were clearly observed for all the samples. The coercivity μ0Hc was improved by introducing an Al cap layer and it was further increased by heat treatment. A high μ0Hc of 1.78 T was obtained at 400 ºC by increasing the annealing time to 4 hours. It was considered that infiltration of Al into the Sm(Fe-Co)-B layer contributed to the improvement of magnetic properties.