Method for producing nanoparticle layer having uniform easy axis of magnetization, magnetic recording medium having such layer, its production method, and its production apparatus

Abstract

The magnetic recording medium provided is produced by forming a substrate having a nanoparticle layer comprising an array of nanoparticles, and an organic compound between said array of nanoparticles; irradiating the nanoparticle layer with an infrared beam to magnetize the nanoparticles; applying a magnetic field to the nanoparticle layer to orient easy axis of magnetization of the magnetic nanoparticles in a substantially uniform direction; and irradiating the nanoparticle layer with an ultraviolet beam to bind said organic compound to thereby produce a magnetic recording medium wherein easy axis of magnetization of the nanoparticles has been oriented in a direction substantially parallel to a direction at a particular angle with the substrate. The resulting magnetic recording medium experiences no deterioration of the underlying layer or the soft magnetic layer, and exhibits good magnetic properties.

1 . An apparatus for producing a magnetic recording medium comprising:
 an infrared irradiating section for irradiating a substrate having a nanoparticle layer formed thereon with an infrared beam having the capability to magnetize nanoparticles and to produce magnetic nanoparticles, wherein said nanoparticle layer comprises an array of nanoparticles having an average particle size of at least 1 nm and not more than 20 nm, and containing at least one element selected from the group consisting of Fe, Co, Ni, Mn, Sm, Pt, or Pd, and an organic compound between said array of nanoparticles;   a magnetic field applying section wherein a magnetic field is applied to said nanoparticle layer to orient an easy axis of magnetization of said magnetic nanoparticles in a substantially uniform direction; and   an ultraviolet irradiating section wherein said nanoparticle layer is irradiated with an ultraviolet beam to bind said organic compound.   
   
   
       2 . An apparatus for producing a magnetic recording medium according to  claim 1  wherein said apparatus further comprises:
 a rotating section which rotates said substrate bearing said nanoparticle layer at an arbitrary rotation speed around a particular axis of rotation;   wherein said infrared irradiating section for irradiating a particular region of said substrate with the infrared beam, said magnetic field applying section for applying a magnetic field to said particular region after the infrared irradiation is applied, and said ultraviolet irradiating section for irradiating said particular region of said substrate with the ultraviolet beam after the magnetic field application is applied, are concentrically arranged around the center of rotation.