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:
Dec. 11, 2012
Filed:
Jul. 01, 2005
Shunji Takenoiri, Nagano, JP;
Yasushi Sakai, Nagano, JP;
Shunji Takenoiri, Nagano, JP;
Yasushi Sakai, Nagano, JP;
Fuji Electric Co., Ltd., , JP;
Abstract
A perpendicular magnetic recording medium is disclosed that achieves improved recordability without deteriorating thermal stability by reducing the switching field. A perpendicular magnetic recording medium of the invention has a first magnetic recording layer and a second magnetic recording layer between with is interposed a coupling layer that ferromagnetically couples the two layers. The first and second magnetic recording layers satisfy an inequality KuT>KuTin the case where Hk>Hkand an inequality KuT<KuTin the case where Hk<Hk, where Hkand Hkare anisotropy magnetic fields, Kuand Kuare uniaxial anisotropy constants, and Tand Tare thicknesses of the first magnetic recording layer and the second recording layer, respectively. An exchange coupling energy between the magnetic recording layers is preferably at least 5×10erg/cm. Advantageously, the coupling layer is mainly composed of a material selected from V, Cr, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Ta, W, Re, and Ir, and has a thickness of at most 2 nm. At least one of the magnetic recording layers preferably has a granular structure.