Patent ID: 7514162
Filing Date: 2009-04-07
Classification: G11B

Abstract:
1. A perpendicular magnetic recording medium comprising: a substrate; an underlayer of magnetically permeable material on the substrate; a perpendicular magnetic recording layer comprising a granular Co alloy having perpendicular magnetic anisotropy on the underlayer; an antiferromagnetically-coupled (AFC) layer between the underlayer and the recording layer and having perpendicular magnetic anisotropy and substantially no net magnetic moment in the absence of an applied magnetic field, the AFC layer comprising a first multilayer of at least one pair of alternating first and second films, a second multilayer of at least one pair of alternating first and second films, and a nonmagnetic antiferromagnetically-coupling layer between the first and second multilayers, the first and second multilayers being perpendicularly antiferromagnetically exchange coupled across the antiferromagnetically-coupling layer and having perpendicular magnetizations substantially antiparallel in the absence of an applied magnetic field and substantially parallel in the presence of a magnetic field above a threshold field, the first film being Co or a Co alloy and the second film being selected from the group consisting of Pt, Pd, Au and Ni; a nonmagnetic separation layer between the AFC layer and the underlayer; and an exchange-break layer between the AFC layer and the recording layer for magnetically decoupling the recording layer and the AFC layer.