Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-09-30
2002-05-07
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S327310
Reexamination Certificate
active
06385017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to magnetoresistive (MR) sensors and more particularly to MR sensor devices and methods of fabrication thereof.
2. Description of Related Art
Kim et al., U.S. Pat. No. 5,608,593 for “Shaped Spin Valve Type Magnetoresistive Transducer and Method for Fabricating the Same Incorporating Domain Stabilization Technique” shows a spin valve (SV) with a permanent magnet with a non-magnetic (e.g., Cr) underlayer (Separation layer). (See col. 5, lines 15 to 25.)
Ravipati, U.S. Pat. No. 5,709,358 for a “Spin Valve Magnetoresistive Transducers Having Permanent Magnets” has thin film layers of ferromagnetic material separated from each other by a nonmagnetic spacer. The direction of magnetization of one thin ferromagnetic layers is pinned by a permanent magnetic layer. Another permanent magnetic layer is located adjacent to the other thin film layer to provide longitudinal biasing.
Mauri, U.S. Pat. No. 5,796,561 for a “Self-biased Spin Valve Sensor” discloses a Spin Valve (SV) MagnetoResistive (MR) sensor with a free layer separated from a pinned layer by a spacer layer.
Takada et al., U.S. Pat. No. 5,828,527 for a “Thin Film Magnetic Head Having Magnetic Resistance Effect Stabilizing Layer” describes a thin film magnetic head with a magnetoresistance effect stabilizing layer with an underlayer of Ta or oxides of Al or Si, a buffer layer of chromium (Cr), a separation layer of Cr or Ta and a hard magnetic layer.
SUMMARY OF THE INVENTION
A spin valve device comprises a free layer, a spacer layer, a pinned layer, an antiferromagnetic layer, and a patterned underlayer that includes a magnetic material for providing trackwidth and longitudinal bias. The patterned underlayer can comprises a buffer layer, an antiferromagnetic layer and a ferromagnetic layer. Alternatively, the patterned underlayer can comprises a buffer layer, a chromium layer and a magnetically hard, i.e. permanently magnetic, layer which provides trackwidth, longitudinal bias, and magnetic stabilization.
In accordance with this invention a continuous fee layer spin valve (SV) Sensor with a patterned exchange underlayer stabilization. The underlayer (antiferromagnet) is formed under the magnetically hard or permanently magnetic (PM) material.
REFERENCES:
patent: 5508866 (1996-04-01), Gill et al.
patent: 5608593 (1997-03-01), Kim et al.
patent: 5668688 (1997-09-01), Dykes et al.
patent: 5708358 (1998-01-01), Ravipati
patent: 5796561 (1998-08-01), Mauri
patent: 5828527 (1998-10-01), Takada et al.
patent: 5923503 (1999-07-01), Sato et al.
patent: 6103136 (2000-08-01), Han et al.
patent: 6111722 (2000-08-01), Fukuzawa et al.
Dover Moris Musa
Min Tai
Wang Po-Kang
Headway Technologies Inc.
Jones II Graham S.
Watko Julie Anne
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