Multilayer-based magnetic media with hard ferromagnetic, anti-ferromagnetic, and soft ferromagnetic layers

A high areal recording density, perpendicular magnetic recording medium, comprising:

• (a) a non-magnetic substrate having a surface with a layer stack formed thereon, said layer stack comprising, in overlying sequence from said substrate surface:
• (b) a soft ferromagnetic underlayer, said soft magnetic underlayer (b) being from about 1,500 to about 5,000 Å thick, having a saturation moment Bsat as high as about 30,000 Gauss, and comprising a material selected from the group consisting of NiFe, CoNiFe, CoZrNb, FeTaC, FeCoB, and FeAlNx,
• (c) an anti-ferromagnetic coupling layer structure, said anti-ferromagnetic coupling layer structure (c) comprising a layer stack composed of at least one ferromagnetic layer of Co and at least one anti-ferromagnetic layer of Ru, said layer stack being selected from the group consisting of Co/Ru, Ru/Co/Ru, and Ru/Co/Ru/Co layer stacks, wherein each Co layer is about 3 Å thick and each Ru layer is from about 8 to about 10 Å thick;
• and
• (d) a hard ferromagnetic perpendicular recording layer including a multilayer magnetic superlattice structure;
• wherein layers (b), (c), and (d) in stacked combination provide said medium with improved thermal stability and a high perpendicular coercivity which can exceed about 6,500 Oe.