Patent ID: 7767322

Claim:
A perpendicular magnetic recording medium, comprising: a substrate; a soft-magnetic underlayer on the substrate; a seed layer formed from an amorphous material on the soft-magnetic underlayer; an underlayer formed from Ru on the seed layer, the underlayer including a plurality of granular crystals each growing in a direction perpendicular to a surface of the substrate, and a plurality of empty interstices separating the granular crystals from each other; a recording layer on the underlayer, the recording layer including a plurality of magnetic particles each having an easy axis of magnetization substantially perpendicular to the surface of the substrate, and a plurality of non-magnetic immiscible phases separating the magnetic particles from each other; a second underlayer between the seed layer and the underlayer; and a grain embryo layer including a plurality of isolate grain embryos directly on a surface of the seed layer, wherein the second underlayer includes a plurality of second granular crystals formed from Ru and a plurality of polycrystalline films, each of the polycrystalline films being formed by the second granular crystals coupled with each other through granular boundaries, wherein the second underlayer is formed so that the second granular crystals cover the grain embryos, wherein intervals between the granular crystals in the underlayer are in a range from 1 nm to 2 nm, and wherein the grain embryo layer is formed from a material including at least one of Pt, W, Ag, Au, and alloys of Pt, W, Ag, Au.