Thermal stability of Co/sub 80/Pt/sub 20/-SiO/sub 2/ granular films sputtered on DC pulse biased substrates

Granular Co/sub 80/Pt/sub 20/-SiO/sub 2/ films have been prepared with thicknesses of /spl sim/15 nm using a novel pulsed dc bias technique. This enabled the growth of thermally stable films with coercivities as high as 2.3 kOe without annealing. The CoPt granules are randomly oriented with a slight (1010) texture with diameters of 5-10 nm at 51% CoPt volume fraction. Measurement of the time-dependent coercivity was used to extract the value of intrinsic switching field Ho and the thermal stability factor KV/kT by fitting to Sharrock's formula. The value of H/sub 0/ decreases from 3.5 kOe at 41% CoPt to 2.5 kOe at 58% CoPt while KV/kT increases from 78 to a maximum of 236 at 56% CoPt before decreasing to 160 at 58% CoPt. The coercivity was relatively flat from 45% to 58% CoPt, presumably because of the offsetting effects of the increase in H/sub 0/ and the decrease in KV/kT over this range.