The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 25, 1999
Filed:
Aug. 15, 1995
Yotsuo Yahisa, Odawara, JP;
Yoshibumi Matsuda, Odawara, JP;
Joe Inagaki, Tokyo, JP;
Enji Fujita, Odawara, JP;
Takao Yonekawa, Odawara, JP;
Mitsuhiro Shoda, Odawara, JP;
Akira Kato, Odawara, JP;
Yuzuru Hosoe, Hino, JP;
Masukazu Igarashi, Kawagoe, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A magnetic recording medium has a substrate made of a nonmetal nonmagnetic material whose coefficient of linear expansion lies within a range from 0.000013/deg to 0.0001/deg. A magnetic layer is formed on the substrate as a thin polycrystalline film or a thin amorphous film. The magnetic layer has Co as a main component, which exhibits a negative magnetostrictive constant so that its coercive force rises in the direction of compressive strain. The magnetic layer is subjected to an in-plane compressive strain from the substrate due to a difference between the coefficient of thermal expansion of the substrate and the magnetic layer so that high coercivity is obtained in the magnetic layer.