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:
Apr. 27, 2010
Filed:
May. 01, 2006
Hiroyuki Suzuki, Kanagawa, JP;
Hidekazu Kashiwase, Kanagawa, JP;
Akira Morinaga, Kanagawa, JP;
Tatsuya Hinoue, Kanagawa, JP;
Hiroyuki Suzuki, Kanagawa, JP;
Hidekazu Kashiwase, Kanagawa, JP;
Akira Morinaga, Kanagawa, JP;
Tatsuya Hinoue, Kanagawa, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
A bit error rate is improved and, at the same time, an aging change due to thermal fluctuation is decreased. In one embodiment, a magnetic recording medium has first, second, third, and fourth magnetic layers stacked over the underlayer film on a substrate. The product (Brt2) of the residual magnetic flux density and film thickness of the second magnetic layer is smaller than the product (Brt3) of the residual magnetic flux density and film thickness of the third magnetic layer. The second magnetic layer has a thickness larger than that of the third magnetic layer and is anti-ferromagnetically coupled with the first magnetic layer by way of the first non-magnetic intermediate layer. The fourth magnetic layer is formed by way of a second non-magnetic intermediate layer above the third magnetic layer. The product (Brt4) of the residual magnetic flux density and film thickness of the fourth magnetic layer is from about 47% to 52% of the product (Brt_total) of the residual magnetic flux density and film thickness of the entire magnetic layers in a state of residual magnetization with the external magnetic field removed.