Perpendicular magnetic recording medium, manufacturing process of the same, and magnetic recording/reproducing apparatus using the same

Abstract

Embodiments of the invention provide a perpendicular magnetic recording medium improved for fly ability, high in read signal quality, and capable of suppressing magnetic decay of recorded magnetization to be caused by stray fields. In one embodiment, a perpendicular recording layer is formed over a substrate with a soft magnetic underlayer therebetween, then an amorphous or nano-crystalline layer is formed between the substrate and the soft magnetic underlayer. The soft magnetic underlayer includes first and second amorphous soft magnetic layers, as well as a nonmagnetic layer formed between those first and second amorphous soft magnetic layers. The first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of the substrate respectively and coupled with each other antiferromagnetically.

1 .- 11 . (canceled) 
     
     
         12 . A method for manufacturing a perpendicular magnetic recording medium, comprising:
 forming an amorphous layer or nano-crystalline layer over a substrate;   forming a first amorphous soft magnetic layer on said amorphous layer or nano-crystalline layer;   cooling said substrate while applying a magnetic field to said substrate in a radial direction thereof; and   forming a nonmagnetic layer on said first amorphous soft magnetic layer;   forming a second amorphous soft magnetic layer on said nonmagnetic layer;   forming a perpendicular recording layer on said second amorphous soft magnetic layer.   
     
     
         13 . The method according to  claim 12 , wherein cooling said substrate while applying a magnetic field to said substrate in the radial direction thereof is provided just after forming said second amorphous soft magnetic layer. 
     
     
         14 . The method according to  claim 12 , wherein said substrate is cooled under 100° C. in said step of cooling. 
     
     
         15 . The method according to  claim 12 , wherein said first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of said substrate respectively and coupled with each other antiferromagnetically. 
     
     
         16 . A method for manufacturing a perpendicular magnetic recording medium, comprising:
 forming an amorphous layer or nano-crystalline layer over a substrate;   forming a first amorphous soft magnetic layer on said amorphous layer or nano-crystalline layer;   forming a nonmagnetic layer on said first amorphous soft magnetic layer;   forming a second amorphous soft magnetic layer on said nonmagnetic layer;   cooling said substrate while applying a magnetic field to said substrate in a radial direction thereof; and   forming a perpendicular recording layer on said second amorphous soft magnetic layer.   
     
     
         17 . The method according to  claim 16 , wherein said nonmagnetic layer is formed between ferromagnetic layers. 
     
     
         18 . The method according to  claim 16 , wherein said nonmagnetic layer contains an alloy made of a nonmagnetic material and a ferromagnetic material. 
     
     
         19 . The method according to  claim 16 , wherein cooling said substrate while applying a magnetic field to said substrate in a radial direction thereof is provided just after forming said first amorphous soft magnetic layer. 
     
     
         20 . The method according to  claim 16 , wherein said substrate is cooled under 100° C. in said step of cooling. 
     
     
         21 . The method according to  claim 16 , wherein said first and second amorphous soft magnetic layers are given uniaxial magnetic anisotropy in the radial direction of said substrate respectively and coupled with each other antiferromagnetically. 
     
     
         22 .- 25 . (canceled)