Patent ID: 7799446

Claim:
A perpendicular magnetic recording medium comprising: a substrate; a soft-magnetic backing layer formed over said substrate; an orientation control layer formed over said soft-magnetic backing layer; a first foundation layer of a continuous film of Ru or a Ru alloy formed on said orientation control layer; a second foundation layer comprising a plurality of crystal grains of Ru or a Ru alloy formed on said first foundation layer with a gap separating said plurality of crystal grains from each other; and a recording layer comprising a plurality of magnetic particles formed on said second foundation layer respectively in correspondence to said plurality of crystal grains, each of said plurality of magnetic particles having an easy axis of magnetization in a direction generally perpendicular to a substrate surface, and a non-magnetic grain boundary phase isolating said plurality of magnetic particles from each other, wherein said first foundation layer comprises a plurality of crystal grains formed in contact with each other at respective grain boundaries, one of said plurality of crystal grains constituting said second foundation layer being formed in correspondence to one of said plurality of crystal grains constituting said first foundation layer, wherein there are provided a plurality of nuclei at an interface between said one crystal grain of said plurality of crystal grains constituting said first foundation layer and said orientation control layer, and wherein each of said plurality of nuclei comprises any of the elements of Pt, W, and CoPt or an alloy containing one or more of said elements.