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:
Jun. 11, 2002
Filed:
Mar. 14, 2000
Tetsuya Kanbe, Yokohama, JP;
Yoshio Takahashi, Kunitachi, JP;
Akira Ishikawa, Kodaira, JP;
Ichiro Tamai, Yokohama, JP;
Yuzuru Hosoe, Hino, JP;
Yoshifumi Matsuda, Odawara, JP;
Kiwamu Tanahashi, Fujisawa, JP;
Tomoo Yamamoto, Hachioji, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
The present invention provides a magnetic recording medium having a magnetic layer deposited on a substrate through a single-layer underlayer or a multilayer-underlayer, the magnetic layer includes magnetic crystal grains having an acicular structure or amorphous magnetic particles, an average grain size of the magnetic grain and a grain-size dispersion normalized by the average grain size are less than 16 nm and less than 0.5, respectively, a value Ku·v/kT which results from dividing a product of a magnetic anisotropy constant Ku and a volume v of the magnetic grain by a product of a Boltzmann constant k and an absolute temperature T is selected to be greater than 60, and a film thickness of the magnetic layer falls within twice of the average grain size. Thus, there can be realized a magnetic recording system in which a media noise can be reduced, a high S/N and a low bit error rate can be obtained and which has a high recording density of 2 gigabits per one square inches and an MTBF (mean time between failure) of higher than 300000 hours.