Patent ID: 6183893
Filing Date: 2001-02-06
Classification: G11B,Y10S,Y10T

Abstract:
A perpendicular magnetic recording medium having a perpendicular magnetic film formed through an underlayer on a nonmagnetic substrate,the underlayer which includes a material having a hexagonal close packed structure or an amorphous structure, comprising:a first underlayer nearer to the substrate; anda second underlayer having a hexagonal (close packed structure formed on the first underlayer, a preferred growth of [0001] and a material capable of hetero-epitaxy growth onto the perpendicular magnetic film,wherein the perpendicular magnetic film formed on the second underlayer includes a lower perpendicular magnetic layer contacting the second underlayer and an upper perpendicular magnetic layer formed thereon, the perpendicular magnetic film including the lower and upper layers is a Co-alloy polycrystal film, the total concentration of added nonmagnetic elements in the upper perpendicular magnetic layer is lower than that in the lower perpendicular magnetic layer, the saturation magnetization Ms and the magnetic anisotropic energy Ku of the upper perpendicular magnetic layer are larger that those of the lower perpendicular magnetic layer, continues hetero-epitaxy growth from the second underlayer to the upper perpendicular magnetic layer is realized, the total thickness of the perpendicular magnetic film is from 5 to 70 nm, and the average grain size of crystal grains in the upper perpendicular magnetic layer is from 5 to 15 nm on the basis of measurement at the surface side of the upper perpendicular magnetic layer.