Patent ID: 7572527

Claim:
A perpendicular magnetic recording medium comprising: a substrate; an underlayer of magnetically permeable material on the substrate; an antiferromagnetically-coupled (AFC) layer comprising first and second ferromagnetic layers separated by a nonmagnetic antiferromagnetically-coupling layer, the second ferromagnetic layer comprising a granular CoPtCr alloy having a hexagonal-close-packed crystalline structure with the c-axis oriented substantially perpendicular to the layer, the first ferromagnetic layer having a hexagonal-close-packed crystalline structure with the c-axis oriented substantially perpendicular to the layer and a composition different from the composition of the CoPtCr alloy of the second ferromagnetic layer so as to provide the first ferromagnetic layer with an anisotropy field lower than the anisotropy field of the second ferromagnetic layer, whereby the first ferromagnetic layer has a magnetic permeability higher than the magnetic permeability of the second ferromagnetic layer by at least 1.5; and an exchange break layer between the underlayer and the first ferromagnetic layer for magnetically decoupling the underlayer and the first ferromagnetic layer and for inducing the substantially perpendicular c-axis orientation of the first ferromagnetic layer.