The effect of carbon overcoat diffusion on CoCrTa/Cr thin-film media

The effect of carbon and chromium diffusion on CoCrTa thin-film media was studied. RES (Rutherford Backscattering) data and TEM (Transmission electron microscopy) micrographs indicate that the CoCr14Ta6 film has a higher film density than the CoCr14Ta4 film. SIMS (Secondary Ion Mass Spectroscopy) data shows that Ta enhances the carbon diffusion into the magnetic layer and that Cr diffusion is not detectable in our process temperature range. The M-s (saturation magnetization) of the two alloys decreases as the magnetic thickness decreases, which may be due to the low film density of the magnetic layer and carbon diffusion into the magnetic layer. Carbon diffusion from the overcoat will play an important role in the performance of future low thickness MR media.