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:
Jan. 03, 2012
Filed:
Oct. 29, 2009
Fumiko Akagi, Fuchu, JP;
Masukazu Igarashi, Kawagoe, JP;
Hiroaki Nemoto, Odawara, JP;
Takayuki Ichihara, Tokyo, JP;
Fumiko Akagi, Fuchu, JP;
Masukazu Igarashi, Kawagoe, JP;
Hiroaki Nemoto, Odawara, JP;
Takayuki Ichihara, Tokyo, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A thermally assisted magnetic recording medium includes a substrate and at least two, i.e., first and second magnetic recording layers. These layers are hard magnetic layers and contain magnetic grains and a non-magnetic substance magnetically segregating the magnetic grains at grain boundaries. The first magnetic recording layer has a magnetic anisotropy energy K, a grain volume v, and energy for maintaining its recording magnetization Kv; the second magnetic recording layer has a magnetic anisotropy energy K, a grain volume v, and energy for maintaining its recording magnetization Kv; and the ratio Kv/kT of Kvto a thermal fluctuation energy kT, where krepresents a Boltzmann constant and T represents an absolute temperature, and the ratio Kv/kT of Kvto kT satisfy the following conditions: Kv/kT is larger than Kv/kT at room temperature, but is smaller than Kv/kT at temperatures around the Curie temperature of the first magnetic recording layer.