| 摘要 |
A FePt alloy nanoparticle, which is expected to be a promising material used for an ultra-high-density magnetic recording medium of the next generation, is ordered by heat treatment to have high magnetic anisotropy, but there has been a problem that the particles are coalesced with each other and agglomerate during the heat treatment. According to the present invention, each particle of the alloy nanoparticles is covered with a coating such as SiO<SUB>2</SUB>, and thereafter a heat treatment for ordering is carried out. In this method, the alloy nanoparticles do not coalesce with each other even if the heat treatment is performed at such a high temperature as to allow all the particles to be fully ordered. After the heat treatment, only the coating is removed using an acid or alkali solution so that it is possible to obtain ordered alloy phase nanoparticles which are ordered and dispersible in various solutions. It is also possible to easily manufacture an ultra-high-density magnetic recording medium by coating surfaces of a substrate with a binder solution in which the particles are dispersed while applying a magnetic field in a predetermined direction.
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