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. 04, 2012
Filed:
Jan. 10, 2005
Osamu Kitakami, Sendai, JP;
Yutaka Shimada, Sendai, JP;
Satoshi Okamoto, Sendai, JP;
Takehito Shimatsu, Natori, JP;
Hajime Aoi, Sendai, JP;
Hiroaki Muraoka, Sendai, JP;
Yoshihisa Nakamura, Sendai, JP;
Hiroyuki Uwazumi, Shinagawa-ku, JP;
Tadaaki Oikawa, Yokosuka, JP;
Osamu Kitakami, Sendai, JP;
Yutaka Shimada, Sendai, JP;
Satoshi Okamoto, Sendai, JP;
Takehito Shimatsu, Natori, JP;
Hajime Aoi, Sendai, JP;
Hiroaki Muraoka, Sendai, JP;
Yoshihisa Nakamura, Sendai, JP;
Hiroyuki Uwazumi, Shinagawa-ku, JP;
Tadaaki Oikawa, Yokosuka, JP;
Abstract
There is provided a perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate, and at least a nonmagnetic underlayer, a magnetic recording layerand a protective layerformed in this order on the nonmagnetic substrate, the magnetic recording layercomprises a low Kregionlayer having a perpendicular magnetic anisotropy constant (Kvalue) of not more than 1×10erg/cm, and a high Kregionlayer having a Kvalue of at least 1×10erg/cm. Moreover, the magnetic recording layeris made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.