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. 20, 2010
Filed:
Jan. 09, 2007
Ichiro Tamai, Kanagawa, JP;
Ikuko Takekuma, Kanagawa, JP;
Hiroaki Nemoto, Kanagawa, JP;
Yoshiyuki Hirayama, Tokyo, JP;
Ichiro Tamai, Kanagawa, JP;
Ikuko Takekuma, Kanagawa, JP;
Hiroaki Nemoto, Kanagawa, JP;
Yoshiyuki Hirayama, Tokyo, JP;
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
Embodiments in accordance with the present invention provide a perpendicular recording medium with low noise and high recording density by reducing the effects from noise generated from the vicinity of the interface with the intermediate layer of the recording layer, in a perpendicular recording medium utilizing a granular recording layer containing oxygen or oxide additive in a cobalt-chromium alloy formed on an intermediate layer with a ruthenium or ruthenium alloy layer. A first recording layer and a second recording layer are formed in order on an intermediate layer of ruthenium or ruthenium alloy. The first recording layer and the second recording layer are comprised of cobalt as the main material in a granular structure containing chromium and oxygen. The saturation magnetization of the first recording layer is lower than the saturation magnetization of the second recording layer. When a first recording layer saturation magnetization is set as Ms(emu per cubic centimeter), a second recording layer saturation magnetization is set as Ms(emu per cubic centimeter), and the first recording layer film thickness is set to t(nm), then (Ms−Ms)×twill be larger than 0 (memu per square centimeter) and smaller than 0.15 (memu per square centimeter).