Thickness reduction in CoPtCr-SiO2 perpendicular recording media to improve media performance

Magnetic properties and recording performance of thin CoPtCr-SiO2 media were examined in relation to thermal stability. Magnetic anisotropy K-u of {(Co90Cr10)(80)Pt-20}(89)(SiO2)(11) media maintains a constant value of around 5.5 x 10(6) erg/cm(3), even at film thickness of 4 nm. This K-u value corresponds to the anisotropy energy of the grains K-u(g) calculated by taking account of the volume fraction of about 8 x 10(6) erg/cm(3), indicating a high potential to resist thermal agitation. The high K-u derives a high remanence corcivity H, of similar to 4 kOe, even at film thickness of 8 nm, resulting in a loop squareness of nearly 1. The ratio of magnetic anisotropy energy to thermal energy KuVact/kT maintained a value of more than 70, even at this thickness. The media noise at low recording density increases with decreasing film thickness below 8 run, probably due to the thermal agitation. The recording resolution D-50 showed a broad maximum of similar to 420 kFCI at around this thickness. The reduction in film thickness improves recording resolution; however, it is likely that the large thermal agitation in the thin-film region degrades the recording resolution, resulting in an optimum thickness to show the highest recording resolution.