A recording medium consists of a composite amorphous magnetic material layer comprising a rare earth metal and an iron family metal, the composition ratio thereof being nonuniform in the perpendicular direction. Because of the nonuniform composition ratio, a minute magnetic domain can be formed stably, so that thermo magnetic recording at extremely high density and sensitivity can be effected. Where GdFe is employed as a suitable material, the thickness of a portion of the magnetic layer, which portion has a larger perpendicular magnetic anisotropy caused by the nonuniform composition ratio, is increased preferably in comparison with the other portion. Uniform thermo magnetic recording can be performed on the large area medium by covering the same with a transparent dielectric material layer having nonuniform thickness.
A magneto-optical recording medium with wide operating margins is disclosed. The magneto-optical recording medium includes a vertical magnetic films of exchange-coupled liminated structure composed of a first magnetic layer with a high coercive force H.sub.H and a low Curie temperature T.sub.L and a second magnetic layer with a lower coercive force H.sub.L and a higher Curie temperature T.sub.H in comparison with those of the first magnetic layer. The first magnetic layer has a gradient of the Curie temperature along the direction of thickness of the layer so that the Curie temperature is higher at a position closer to the second magnetic layer. The recording method utilizing the recording medium according to the present invention is also disclosed.
4489139 - Magneto-optic memory medium - Owned by Sharp Kabushiki Kaisha (Osaka,JP) [*] Notice:The portion of the term of this patent subsequent to June 28, 2000 has been disclaimed.
A magneto-optic memory medium is disclosed which is made up by an acryl resin substrate having strip-like grooves, a magneto-optic magnetization film disposed on the substrate and having an axis of easy magnetization perpendicular to its surface. The magnetization film is made of amorphous ferromagnetic material such as GdTbFe, GdTbDyFe, SmTbFe, GdDyFe, TbCo or the like. A reflective film is provided overlying the magneto-optic magnetization film.
A magnetic recording medium having a thin magnetic amorphous rare earth metal-transition metal alloy film is disclosed, the amorphous alloy film having an axis of easy magnetization in a direction substantially vertical to the film surface and containing a crystalline phase in the amorphous phase. The magnetic recording medium exhibits high coercive force over a wide compositional range.
An optico-thermal magnetic recording medium comprises a substrate, a first layer of a ternary amorphous alloy represented by Tb.sub.x (Fe.sub.1-y Co.sub.y).sub.1-x or Dy.sub.x (Fe.sub.1-y Co.sub.y).sub.1-x on axis of easy magnetization perpendicular to the film plane of the layer, a second layer of ternary amorphous magnetic alloy represented by Tb.sub.x (Fe.sub.1-y Co.sub.y).sub.1-x or Dy.sub.x (Fe.sub.1-y Co.sub.y).sub.1-x having and axis of easy magnetization perpendicular to the film plane of the layer, the first and the second layers being formed one on another, light being incident on the side of the first layer, the first and the second layers having magnetic layers exchange-coupled. In the first layer 0.15.ltoreq.x.ltoreq.0.2, and 0<y<0.5. In the second layer 0.2<x.ltoreq.0.35, and 0<y<0.5. At room temperature, the first layer has magnetic dominance of FeCo Sub-lattice, and the second layer has magnetic dominance of Tb or Dy sub-lattice.
A recording medium comprises a first layer prepared from a material of perpendicular anisotropy, a second layer prepared from a compound of noncrystalline rare earth metal--3d transition metal and deposited on said first layer, and a transparent protective layer and mounted on said second layer. Data is magnetically recorded on the recording medium and the recorded data is optically read by utilizing the magneto-optics effects.
