A granular perpendicular magnetic recording medium, comprising: (a) a
non-magnetic substrate having a surface; and (b) a layer stack on the
substrate surface, the layer stack including a granular perpendicular
magnetic recording layer formed by: (1) reactively sputtering a target
comprised of a magnetic alloy in an atmosphere containing at least one
ionized oxygen species derived from a source gas comprised of a compound
of oxygen and at least one other non-metallic element; and (2) oxidizing
an exposed upper surface of the granular perpendicular magnetic recording
layer by generating a plasma containing at least one ionized oxygen
species derived from a source gas comprised of a compound of oxygen and
at least one other non-metallic element and treating the exposed upper
surface of the granular perpendicular magnetic recording layer with the
plasma.