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:
Aug. 21, 2012
Filed:
Oct. 02, 2008
Yuzo Sasaki, Ichihara, JP;
Yuzo Sasaki, Ichihara, JP;
Showa Denko K.K., Tokyo, JP;
Abstract
The present invention relates to a perpendicular magnetic recording medium including a nonmagnetic substrate, and at least a soft magnetic layer (SUL), an alignment control layer, a magnetic recording layer and a protective layer formed on the nonmagnetic substrate; wherein the magnetic recording layer is constituted of three or more layers and includes a first magnetic recording layer, a second magnetic recording layer and a third magnetic recording layer from the substrate side, and also includes an exchange coupling reduction layer for reducing exchange coupling of both layers between the second magnetic recording layer and the third magnetic recording layer and, regarding magnetocrystalline anisotropic energy Kof each magnetic recording layer, the first magnetic recording layer has 4×10erg/cc or higher, the second magnetic recording layer has 2×10erg/cc or lower and the third magnetic recording layer has 1×10erg/cc or lower. The present invention also relates to a magnetic recording and reproducing apparatus using the perpendicular magnetic recording medium.