A process is disclosed for forming magnetic media, in which a protective overcoat of either partially stabilized zirconia or partially stabilized hafnia directly overlies a magnetic thin film recording layer. First, a chromium underlayer is sputter deposited onto a planar aluminum nickel phosphorous substrate. A crystalline magnetic recording layer is deposited onto the chromium underlayer, and substantially replicates the crystalline orientation of the underlayer. The substrate, underlayer and recording layer are passivated briefly in an oxygen atmosphere. Then, the hafnia or zirconia underlayer is applied by RF reactive sputtering in an atmosphere of argon and oxygen, with the argon partial pressure at least ten times the oxygen partial pressure. The passivation step improves the adhesion of the subsequently deposited cover layer, while the oxygen in the reactive sputtering process maintains a desired stoichiometric proportion of oxygen in the cover layer, for substantially improved media tribological properties.