Patent ID: 8003237
Filing Date: 2011-08-23
Classification: G11B

Abstract:
1. A perpendicular magnetic recording disk for use in perpendicular magnetic recording, said perpendicular magnetic recording disk: comprising: a base; an underlayer formed over said base for controlling a crystal orientation of an upper layer; a nonmagnetic granular layer of a granular structure formed on said underlayer; and a magnetic recording layer comprising a ferromagnetic layer of a granular structure formed on said nonmagnetic granular layer; wherein said nonmagnetic granular layer comprises: nonmagnetic metal crystal grains which are dispersed in said matrix of said nonmagnetic granular layer and which have a crystal orientation directed in a predetermined orientation that depends on a crystal orientation of said underlayer; and said ferromagnetic layer comprises: magnetic crystal grains which are dispersed in said matrix of said ferromagnetic layer and which have an easy magnetization axis directed in a predetermined orientation that depends on the crystal orientation of said metal crystal grains; wherein the nonmagnetic metal crystal grains of the nonmagnetic granular layer include at least one metal element comprising at least Co or Cr included in the magnetic crystal grains in the ferromagnetic layer; wherein the magnetic recording layer further comprises: a magnetic coupling control layer on the ferromagnetic layer; and an exchange energy control layer which is formed on the magnetic coupling control layer and differs in composition from said ferromagnetic layer; wherein the magnetic coupling control layer controls magnetic coupling between the ferromagnetic layer and the exchange energy control layer and aligns an easy magnetization axis of the ferromagnetic layer and the exchange energy control layer; and wherein the magnetic coupling control layer is formed by Pd or Pt and the exchange energy control layer is formed by a multilayer composed of alternate-layered films.