Stock material or miscellaneous articles – Magnetic recording component or stock – Thin film media
Reexamination Certificate
2005-05-24
2009-08-11
Bernatz, Kevin M. (Department: 1794)
Stock material or miscellaneous articles
Magnetic recording component or stock
Thin film media
C428S827000, C428S828000, C428S828100, C428S830000
Reexamination Certificate
active
07572527
ABSTRACT:
A perpendicular magnetic recording disk has an antiferromagnetically-coupled (AFC) recording layer (RL) comprised of lower and upper ferromagnetic layers, each having a hexagonal-close-packed (hcp) crystalline structure and perpendicular magnetic anisotropy, separated by an antiferromagnetically (AF) coupling layer, wherein the lower ferromagnetic layer (LFM) has substantially higher magnetic permeability than the upper ferromagnetic layer (UFM). The AFC RL is located on an actual exchange break layer (EBL) that separates the AFC RL from the disk's soft magnetic underlayer (SUL). The LFM functions as part of an “effective” exchange break layer (EBL) that also includes the actual EBL and the AF-coupling layer, thereby allowing the actual EBL to be made as thin as possible. The hcp LFM promotes the growth of the hcp UFM in the same way the actual EBL does so that its thickness contributes to the thickness necessary to grow the hcp UFM. The effective EBL appears to be magnetically “thin” during the write process and magnetically “thick” during the readback process.
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Fullerton Eric E.
Lengsfield, III Byron Hassberg
Margulies David
Bernatz Kevin M.
Berthold Thomas R.
Harris Gary D.
Hitachi Global Storage Technologies - Netherlands B.V.
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