Stock material or miscellaneous articles – All metal or with adjacent metals – Having magnetic properties – or preformed fiber orientation...
Reexamination Certificate
2005-04-26
2005-04-26
Bernatz, Kevin M. (Department: 1773)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having magnetic properties, or preformed fiber orientation...
C428S065100, C428S141000, C428S409000, C428S690000, C428S690000
Reexamination Certificate
active
06884521
ABSTRACT:
Disclosed is a magnetic recording medium and a method for manufacturing the same to provide a magnetic recording medium reducing medium noise and having excellent thermal stability. The magnetic recording medium includes a substantially amorphous seed layer and a polycrystal underlayer made of crystal grains having a substantially columnar structure, the polycrystal underlayer contacting thereto. In a boundary between the seed layer and the underlayer, fine grooves having a period up to as large as the magnetic layer crystal grain diameter are formed in the disc circumferential direction. Accordingly, the magnetic recording medium is allowed to have a grain shape with a value obtained by dividing the average grain diameter for the disc circumferential direction by the average grain diameter for the disc radial direction of no less than 0.5 and no more than 0.9, thus achieving simultaneously reduction of the medium noise and thermal stability.
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T. Kanbe, I. Tamai, Y. Takahashi, K. Tanahashi, and Y. Hosoe, “Effects of Boron Addition to Underlayer for CoCrPt Media on Magnetic Characteristics and Microstructure”, IEEE Transactions of Magnetics, vol. 33, No. 5 (Sep. 1997) pp. 2980-2982.
Hirayama Yoshiyuki
Takahashi Yoshio
Yahisa Yotsuo
A. Marquez, Esq. Juan Carlos
Bernatz Kevin M.
Fisher Esq. Stanley P.
Hitachi Global Storage Technologies Japan Ltd.
Reed Smith LLP
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