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:
Mar. 08, 2011
Filed:
Oct. 05, 2004
Tomoyuki Maeda, Kawasaki, JP;
Soichi Oikawa, Tokyo, JP;
Takeshi Iwasaki, Yokohama, JP;
Futoshi Nakamura, Ichikawa, JP;
Hiroshi Sakai, Ichihara, JP;
Kenji Shimizu, Chiba, JP;
Akira Sakawaki, Ichihara, JP;
Tomoyuki Maeda, Kawasaki, JP;
Soichi Oikawa, Tokyo, JP;
Takeshi Iwasaki, Yokohama, JP;
Futoshi Nakamura, Ichikawa, JP;
Hiroshi Sakai, Ichihara, JP;
Kenji Shimizu, Chiba, JP;
Akira Sakawaki, Ichihara, JP;
Showa Denko K.K., Tokyo, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
Abstract
A perpendicular magnetic recording medium includes: a substrate; at least one underlayer formed above the substrate; and a perpendicular magnetic recording layer formed above the at least one underlayer, an easy magnetization axis of the perpendicular magnetic recording layer being oriented perpendicular to the substrate, the perpendicular magnetic recording layer including magnetic crystal particles and grain boundaries surrounding the magnetic crystal particles, wherein the grain boundaries contain an oxide of silicon and at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, and Ba, and the ratio of a total amount of substance of Si, Li, Na, K, Rb, Cs, Ca, Sr, and Ba in the perpendicular magnetic recording layer is no less than 1 mol % and no more than 20 mol %.