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US 6,638,597 B1Granted
Magneto-optical recording medium
AssigneeSony Corporation
InventorsMasataka Shinoda, Yasuhito Tanaka, Takashi Shimouma
Life of this patent
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Abstract
In order to improve reproduction characteristics of a magneto-optical recording medium in a case of being subject to a magnetically induced super resolution readout process utilizing a blue-violet laser beam, there is provided a magneto-optical recording medium having a surface roughness of 0.3 nm or less on a surface of a substrate on which recording/reproduction magnetic layers are formed or a surface of a dielectric film formed on the substrate.
Claims10
A magneto-optical recording medium comprising:
- a transparent substrate having a surface;
- a reproduction layer formed over the surface of said substrate;
- and
- a recording layer formed over said reproduction layer,
- wherein said substrate surface has a surface roughness Ra of 0.3 nm or less,
- said reproduction layer having in-plane magnetization at room temperature and perpendicular magnetization at 150° C. or more;
- and
- said recording layer comprises a first, second and third magnetic films, each made of a rare-earth transition-metal magnetic film being a perpendicular magnetized film having a transition-metal-predominant composition from room temperature to the Curie temperature.
5 more elements
A magneto-optical recording medium comprising
- a transparent substrate;
- a reproduction layer formed over the substrate;
- a recording layer formed formed over the reproduction layer;
- and
- a dielectric film formed between said substrate and said reproduction layer, the dielectric film having a surface roughness Ra of 0.3 nm or less, said reproduction layer having in-plane magnetization at room temperature and perpendicular magnetization at 150° C. or more;
- and
- said recording layer comprises a first, second and third magnetic films, each made of a rare-earth transition-metal magnetic film being a perpendicular magnetized film having a transition-metal-predominant composition from room temperature to the Curie temperature.
4 more elements
Dependencies are inferred from the claim text.