Magnetic recording medium and process for producing the same
AssigneeToda Kogyo Corporation
InventorsTeruaki Santoki, Yasuo Kakihara, Mitsuru Matsuura, Setsuo Yamamoto
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Abstract
A magnetic recording medium, comprises a substrate; and a Co-containing spinel-type iron oxide thin film formed on the substrate, having a Co content of 1 to 20 mol % based on Fe, a coercive force value of not less than 159 kA/m (2,000 Oe), a thickness of 5 to 200 nm, a center line average height Ra of 0.1 to 0.8 nm and a maximum height (Rmax) of not more than 10 nm. The magnetic recording medium is capable of exhibiting a relatively high coercive force, especially a coercive force of not less than 159 kA/m (2,000 Oe) despite as small a film thickness as not more than 200 nm, and an excellent surface smoothness.
Claims6
A magnetic recording medium, comprising:
- a substrate;
- and
- a Co-containing spinel-based iron oxide thin film formed on the substrate, comprising magnetite represented by the general formula of FeOx·Fe2O3 (0<x·1) and maghemite represented by the general formula of γ-Fe2O3, and having a Co content of 1 to 20 mol % based on Fe, a coercive force value of not less than 159 kA/m (2,000 Oe), a thickness of 5 to 200 nm, a center line average height Ra of 0.1 to 0.8 nm, a maximum height (Rmax) of not more than 10 nm, a surface electrical resistance value of not more than 1.5 MΩ and a saturation magnetization value of 29 to 63 Wb/m3 when measured by applying a magnetic field of 1,590 kAfm (20 kOe) thereto.
A magnetic recording medium, comprising:
- a substrate;
- and
- a Co-containing spinel-based iron oxide thin film formed on the substrate, having a Co content of 1 to 20 mol % based on Fe, a thickness of 5 to 200 nm, a center line average height Ra of 0.1 to 0.8 nm, a maximum height (Rmax) of not more than 10 nm, a surface electrical resistance value of not more than 1.5 MΩ, a coercive force value of not less than 159 kA/m (2,000 Oe) and when measured by applying a magnetic field of 1,590 kA/m (20 kOe) thereto, a saturation magnetization value of 29 to 63 Wb/m3.
A magnetic recording medium, comprising:
- a substrate;
- an underlayer formed between the substrate and the Co-containing spinel-based iron oxide thin film, said underlayer having a thickness of not more than 200 nm and being one selected from the group consisting of an oxide thin film having a NaCl-based structure, a metal thin film having a bcc structure, a metal thin film having a B2 structure and an oxide thin film exhibiting an amorphous structure by X-ray analysis;
- and
- a Co-containing spinel-based iron oxide thin film formed on the underlayer, having a Co content of 1 to 20 mol % based on Fe, a thickness of 5 to 200 nm, a center line average height Ra of 0.1 to 0.8 nm and a maximum height (Rmax) of not more than 10 nm, a surface electrical resistance value of not more than 1.5 MΩ, a coercive force value of not less than 159 kA/m and when measured by applying a magnetic field of 1,590 kA/m (20 kOe) thereto, a saturation magnetization value of 29 to 63 Wb/m3.
Dependencies are inferred from the claim text.