Ion beam deposition of carbon overcoats for magnetic thin film media

Ion beam deposited carbon has been investigated for its use as an overcoat for magnetic thin film media. By using a gridless end-Hall ion source, carbon has been deposited that possesses hardnesses to 18 GPa, stress to 4.5 GPa, and densities up to 2.6 g/cc. Contact-start-stop testing of ion beam deposited carbon to fifty thousand cycles shows a marked improvement in failure rate compared to hydrogenated and nitrogenated carbon. Energetic deposition of carbon thin films can lead to implantation of energetic species into the magnetic layer. Simulations have been performed to assess the vulnerability of the magnetic layer to energetic implantation of carbon. In addition, the effect of the partial pressure on the magnetic performance is assessed and a critical impurity concentration defined.