Degree of chemical reaction of carbon and oxygen to ferromagnetic grains for Co-based alloy-oxide granular structure

The saturation magnetization factor, Ms, was investigated for a Co-based alloy-oxide granular film through the quantitative analysis of film composition and phase formation. Using a carbon cap layer deposited directly onto the Co-SiO2 film, both oxidation and carbonization of cobalt caused a reduction in Ms. The composition of the granular film strongly affects Ms, because the Ar gas pressure and discharge power during Co-SiO2 sputtering alters the Co and oxygen content in the film. In particular, for a film fabricated under a high Ar gas pressure such as 8.0 Pa, Ms was significantly decreased, due to the formation of the antiferromagnetic CoO phase.