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, 2004
Filed:
Mar. 19, 2002
Hoa Van Do, Fremont, CA (US);
Mary F. Doerner, Santa Cruz, CA (US);
Eric Edward Fullerton, Morgan Hill, CA (US);
David Thomas Margulies, Gilroy, CA (US);
William G. McChesney, San Jose, CA (US);
Manfred Ernst Schabes, Campbell, CA (US);
Kai Tang, San Jose, CA (US);
Hitachi Global Storage Technologies Netherlands B.V., Amsterdam, NL;
Abstract
A magnetic recording medium for data storage uses a magnetic recording layer having at least two ferromagnetic films with different remanent magnetization-thickness (Mrt) values that are coupled antiparallel across a nonferromagnetic spacer film predominantly by the dipole field (H ) from the grains of the higher-Mrt ferromagnetic film. The material compositions and thicknesses of the ferromagnetic films and the nonferromagnetic spacer film are selected so that H predominates over any antiferromagnetic exchange coupling field (H ) and is greater than the coercive field of the lower-Mrt ferromagnetic film. As a result, the magnetizations of the two ferromagnetic films are antiparallel in the two remanent magnetic states, and thus the net remanent magnetization-thickness product (Mrt) of the recording layer is the difference in the Mrt values of the two ferromagnetic films.