Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-03-20
2002-10-01
Letscher, George J. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06459552
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
Copending application Ser. No. 08/844,511 filed Apr. 18, 1997, assigned to the same assignee, discloses methods of fabricating merged inductive write/magnetoresistive read heads utilizing deposition of different metal layers to produce magnetic heads in which the track width is precisely defined and the write gap and the read gap are accurately aligned relative to each other.
FIELD OF THE INVENTION
This invention relates to the fabrication of thin film magnetic heads and in particular to magnetic heads employing coplanar pole tips.
DESCRIPTION OF THE PRIOR ART
The publication,
Thin Film Head With Staggered Pole Tips,
IEEE Trans. Magn., Volume 27, Number 6, November 1991, page 4710, Wang et al, discusses structures in which the pole tips of a magnetic head overlap each other at their ends in the write gap region, with the amount of the overlap defining the width of the track recorded on a record medium. Such structures are said to relieve the photolithography constraints in pole tip fabrication to permit head fabrication with track widths in the sub-micron range.
SUMMARY OF THE INVENTION
The present invention employs thin film magnetic heads having coplanar pole tips to provide a decrease in the trackwidth of recorded signals on a magnetic record medium. Such a decrease in recorded trackwidth is desirable because it results in an increase in the recorded signal density on the record medium. Coplanar heads of this invention employ magnetic structures in which the magnetic pole tips are coplanar with each other for at least part of their length, and the resulting track width is defined by the thickness of the coplanar pole tips. In one type of such coplanar head, the pole tips are coplanar in a plane extending across the write gap. In another type of coplanar head of this invention, the pole members are spaced from the write gap, and the write gap is formed by thin extensions of the pole members to form pole tips which are coplanar with the plane of the pole members and with a plane across the write gap. Both of these coplanar pole tip configurations result in recorded tracks of decreased trackwidth in the submicron range.
In the embodiment employing coplanar extensions of the pole tips, the extensions can be made of thin and flat materials with high magnetic saturation B
s
properties for optimum magnetic performance. In configurations using such pole tip extensions, the head performance is throat height insensitive.
The invention may be employed in inductive write heads to produce recorded tracks of reduced width. The heads may also be employed in combined inductive write/giant magnetoresistive (GMR) or spin-valve read heads having thin read sensor elements such as multilayered GMR sensors or spin-valve sensors. Such sensors can be incorporated in the head gap, resulting in an integrated head with extremely narrow read widths (≦0.1 &mgr;m). Such multilayered GMR and spin-valve read sensors can be operated in a CIP (current-in-plane) mode or a CPP (current-perpendicular-to-plane) mode.
REFERENCES:
patent: 3668042 (1972-06-01), Farrand
patent: 4885649 (1989-12-01), Das
Liu Francis H.
Tong Hua-Ching
Yuan Samuel W.
Kallman Nathan N.
Letscher George J.
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