A perpendicular magnetic recording disk has a granular cobalt alloy recording layer (RL) containing an additive oxide or oxides, an intermediate layer (IL) as an exchange-break layer on the “soft” magnetic underlayer (SUL), and an ultrathin nucleation film (NF) between the IL and the RL. In the method of making the disk, the IL is deposited at a relatively low sputtering pressure, to thereby reduce the roughness of the RL and overcoat (OC), while the NF and RL are deposited at substantially higher sputtering pressures. The resulting disk has good recording properties and improved corrosion resistance over a comparable disk made with an IL deposited at high sputtering pressure and without the NF. The NF may be a discontinuous film with an average thickness of less than about 1 nm.