| 摘要 |
PURPOSE:To maintain the uniform envelope of the reproduction output of a medium and to maintain the magnetic permeability in the circumferential direction at a specified value by forming a vertical magnetic recording film on the soft amorphous magnetic film on a substrate and annealing the substrate in the magnetic field rotating within the plane parallel with the plane of the substrate. CONSTITUTION:The resin substrate 14 is formed with the soft amorphous magnetic film 20 on one surface thereof by an amorphous alloy target 17 and is then formed with the vertical magnetic recording film 3 on the film 20 by a Co-Cr target 10. A tape-shaped vertical magnetic recording medium manufactured in the above-mentioned way is blanked to a concentrical annular disk and thereafter the magnetic field parallel with the plane of the vertical magnetic recording medium 21 is applied thereto by magnets for forming one directional magnetic field. The rotating magnetic field is effected by rotating said magnets 22, 23 and the medium 21 is annealed for >=2-3hr in a 100-250 deg.C range in said rotating magnetic field, by which the magnetic anisotropy of the films 19, 20 of the disk 21 is made isotropic. The envelope of the reproduction output of the vertical magnetic recording medium is thus made uniform and the magnetic permeability in the circumferential direction is maintained at the specified high value. |
