Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2001-06-21
2004-03-23
Davis, David (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06710982
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to heads for use in a magnetic storage drive. In particular, this invention relates to methods and apparatus for magnetizing shields in such heads.
BACKGROUND OF THE INVENTION
A read/write head in a disc drive typically includes a magnetoresistive (MR) read transducer that is deposited between non-magnetic layers and magnetic shield layers. The magnetoresistive read transducer typically includes a magnetoresistor, electrical contacts and one or more bias magnets that magnetically bias the magnetoresistor, as taught in U.S. Pat. No. 5,018,037 Krounbi et al., for example. Various magnetic biasing arrangements in the magnetoresistive sensor can be used to improve uniformity, predictability, linearity, and/or reduce noise.
Domains formed in the nearby magnetic shield layers can also magnetically bias the magnetoresistor. Control of both domain magnetization direction and domain wall location in the shields are important for the proper operation of the magnetoresistive transducer because of magnetic interaction between the magnetoresistor and the shield.
Some shield designs control the location of domain walls by control of the shield shape. Other shield designs control the polarity of magnetic domains by removing all domain walls and forcing the shield into a single domain state. A side effect of these single domain state designs is that, without closure domains, magnetic charge forms at the edge of the shield that can cause track erasure and loss of data.
A magnetic read/write transducer and a method of making such a magnetic read/write transducer are needed in which magnetic biasing is provided to a shield that reduces track erasures, that provides a low noise, high linearity output, and that is easily manufactured.
SUMMARY OF THE INVENTION
Disclosed is a read/write head that comprises a bottom shield and a shared shield. The shared shield includes a first domain and a plurality of closure domains. The read/write head also includes a magnetoresistive sensor deposited adjacent an air bearing surface between the bottom shield and the shared shield. The magnetoresistive sensor includes a magnetoresistor aligned with the first domain. Non-magnetic material separates the magnetoresistive sensor from the bottom shield and the shared shield. The shared shield includes a shaped feature that defines an unambiguous direction of magnetization for the first domain.
These and various other features as well as advantages that characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.
REFERENCES:
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patent: 4843506 (1989-06-01), Gill et al.
patent: 5018037 (1991-05-01), Krounbi et al.
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patent: 6018443 (2000-01-01), Watanabe et al.
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patent: 61196419 (1986-08-01), None
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Journal of Applied Physics, “Simulation of domain structure for magnetic thin film in an applied field,” vol. 68, No. 1, Jul. 1, 1990, pp. 263-268.
Gangopadhyay Sunita
Mack Anthony M.
Pust Ladislav R.
Rea Christopher J.
Ryan Patrick J.
Davis David
Seagate Technology LLC
Westman Champlin & Kelly
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