Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making named article
Reexamination Certificate
2005-03-08
2005-03-08
McPherson, John A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making named article
C430S322000, C427S526000, C427S523000, C427S531000, C427S128000
Reexamination Certificate
active
06864042
ABSTRACT:
A magnetic recording medium is formed with a distribution of low coercivity regions functioning as a transition pattern for servo information capable of being sensed by a read/write head by exposing a masked magnetic layer to ions to change the coercivity of the exposed magnetic layer without substantially affecting the topography of the magnetic layer.Embodiments of the present invention include forming a series of substantially radially extending low coercivity regions used to divide the magnetic layer into a plurality of sectors comprising substantially concentric circumferentially extending data tracks by exposing a masked magnetic layer having a high coercivity, i.e. from about 2000 Oe to about 10000 Oe, to one or more heavy atom ion bombardments of gaseous ions, e.g. argon ions, at a dose of about 1×1013atoms/cm2to about 9×1015atoms/cm2having an implantation energy of about 10 KeV to about 50 KeV.
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Gui Jing
Kuo David
Li Xinwei
Chacko-Davis Daborah
McDermott Will & Emery LLP
McPherson John A.
Seagate Technology LLC
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