Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2004-12-17
2008-11-04
Miller, Brian E. (Department: 2627)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C324S252000, C338S03200R
Reexamination Certificate
active
07446987
ABSTRACT:
A hard bias structure for biasing a free layer in a MR element within a magnetic read head is comprised of a soft magnetic underlayer such as NiFe and a hard bias layer comprised of Co78.6Cr5.2Pt16.2or Co65Cr15Pt20that are rigidly exchange coupled to ensure a well aligned longitudinal biasing direction with minimal dispersions. The hard bias structure is formed on a BCC seed layer such as CrTi to improve lattice matching. The hard bias structure may be laminated in which each of the underlayers and hard bias layers has a thickness that is adjusted to optimize the total Hc, Mrt, and S values. The present invention encompasses CIP and CPP spin values, MTJ devices, and multi-layer sensors. A larger process window for fabricating the hard bias structure is realized and lower asymmetry output and NBLW (normalized base line wandering) reject rates during a read operation are achieved.
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Co-pending U.S. Patent App. HT-04-003, U.S. Appl. No. 10/868,716, filed Jun. 15, 2004, “A Novel Hard Bias Design for Extra High Density Recording”, assigned to the same assignee.
Co-pending U.S. Patent App. HT-04-039B, U.S. Appl. No. 11/016,506, filed Dec. 17, 2004, A Novel Hard Bias Design for Sensor Applications, assigned to the same assignee.
Chen Mao-Min
Chien Chen-Jung
Li Min
Torng Chyu-Jiuh
Zhang Kunliang
Ackerman Stephen B.
Headway Technologies Inc.
Kayrish Matthew G
Miller Brian E.
Saile Ackerman LLC
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