Magnetic properties and structure of (Co-alloy)-SiO/sub 2/ granular films

We fabricated (Co-alloy)-SiO/sub 2/ granular films by rf-sputtering with composite target and annealing in a high vacuum environment. The coercivity of the films depended on annealing temperature, the Co-alloy's volume fraction in the film, and other added elements to cobalt. We found that a (Co/sub 85/Pt/sub 15/)/sub 83/-(SiO/sub 2/)/sub 17/ granular film (Co/sub 85/Pt/sub 15/: 64 vol.%) exhibited about 1600 Oe of coercivity at room temperature. The grains diameter was about 50 nm measured by AFM. X-ray diffraction patterns showed that the Co-alloy grains of most films had an fcc-phase structure. From Henkel-plot analysis, the magnetic exchange interaction between the CoPt grains was found to be weak.