COMPOSITION EFFECTS ON RECORDING PROPERTIES OF COPTCR THIN-FILM MEDIA

The effects of different composition of CoPtCr thin-film media on macr omagnetic and recording parameters have been studied. Increasing Cr pe rcentage in the magnetic alloy drops M(5), and consequently M(r) for f ilms of similar squareness, requiring a greater thickness value to ach ieve the same M(r) delta product. Resolution at high recording densiti es degrades with higher M(r) delta as expected. For fixed M(r) delta, resolution drops with the higher delta values as predicted by the thic kness loss factor in the Wallace equation. Low M(r) high delta films h ave worse resolution, but an improvement in media noise is noted. It c ould be argued that this results from greater exchange decoupling from higher intergranular Cr concentrations in the high Cr content, low M( r) alloys. It is speculated here that the noise reduction results from the lower magnetostatic interactions in the film from the decreased v alue of M(5). Recording densities and head-medium spacings have reache d a point where the thin-film media thickness can become a significant loss factor for the short wavelength signals. Thus, the media design must be a compromise for noise and short wavelength amplitude.