Patent ID: 8475947
Filing Date: 2013-07-02
Classification: G11B

Abstract:
1. A perpendicular magnetic recording medium, comprising: a first magnetic recording layer, a second magnetic recording layer, and a third magnetic recording layer disposed sequentially on a nonmagnetic substrate, the first, second and third magnetic recording layers having an easy axis of magnetization in a direction perpendicular to a film plane of the nonmagnetic substrate; and a coupling layer formed between the first and second magnetic recording layers, the first and second magnetic recording layers being ferromagnetically coupled via the coupling layer, wherein the third magnetic recording layer is coupled with the second magnetic recording layer, with no coupling layer formed therebetween; the first and second magnetic recording layers have a granular structure, in which magnetic crystal grains are dispersed in a matrix of nonmagnetic oxides or nonmagnetic nitrides; and the first, second and third magnetic recording layers respectively have a uniaxial anisotropy constant Ku1, Ku2 and Ku3, where Ku1>Ku2>Ku3.