Soft Magnetic Properties and Microstructure of Electroless-Deposited CoB Films.

Abstract

The correlation between the microstructure and the soft magnetic properties of electroless-deposited CoB films was investigated. Adding aminoacetic acid in various concentration to the CoB bath made it possible to control the coercivity of the films without changing their other magnetic properties such as saturation magnetization and squareness. Coercivity was also found to depend on film thickness. TEM observation demonstrated that the difference in coercivity is due to the microstructure, mostly the grain size in the initial deposition region. Films with low coercivity consisted of fine grains (about 10∼20nm in diameter), while those with high coercivity consisted of large grains (about 100nm in diameter). Although no clear differences in microstructure could be observed at the optimum film thickness of 0.5μm, it is suggested that films with low coercivity consist of fine grains from the initial deposition stage.