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. 11, 2009
Filed:
Feb. 18, 2007
Andreas Klaus Berger, San Jose, CA (US);
Eric E. Fullerton, San Diego, CA (US);
Byron Hassberg Lengsfield, Iii, Gilroy, CA (US);
Andreas Klaus Berger, San Jose, CA (US);
Eric E. Fullerton, San Diego, CA (US);
Byron Hassberg Lengsfield, III, Gilroy, CA (US);
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
A perpendicular magnetic recording system uses an exchange-spring type of perpendicular magnetic recording medium. The medium has a recording layer (RL) that includes a lower media layer (ML) and a multilayer exchange-spring layer (ESL) above the ML. The high anisotropy field (high-H) lower ML and the multilayer ESL are exchange-coupled across a coupling layer. The multilayer ESL has at least two ESLs separated by a coupling layer, with each of the ESLs having an Hsubstantially less than the Hof the ML. The exchange-spring structure with the multilayer ESL takes advantage of the fact that the write field magnitude and write field gradient vary as a function of distance from the write pole. The thicknesses and Hvalues of each of the ESLs can be independently varied to optimize the overall recording performance of the medium.