Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-06-07
2002-09-10
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06449133
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetoresistance film and a magnetic read sensor. Namely, the invention concerns a magnetoresistance film having a so-called “spin valve” construction and a magnetic read sensor using the same.
2. Detailed Description of the Prior Art
Conventionally, as a fixed magnetic layer joined to an antiferromagnetic layer in the “spin valve” film, there is generally used a single-layer NiFe/CoFe/CoFeB film that consists of crystalline ferromagnetic material having a fcc structure.
By the way, as an antiferromagnetic layer, in the “spin valve” film using an ordered antiferromagnetic material, it is needed to perform high-temperature heat treatment for the purpose of ordering transformation.
However, in the conventional spin valve film, there was the problem that due to this high-temperature heat treatment the linear response characteristic of the magnetoresistance characteristic decreased and simultaneously with this the layer-to-layer insulative-layer-coupling magnetic field Hf also increased.
A sensor that uses an ordered antiferromagnetic layer is disclosed in Japanese Patent Application Laid-Open No. 6-76247.
On the other hand, a magnetoresistance film that uses an amorphous magnetic alloy as a fixed magnetic layer is disclosed in Japanese Patent Application Laid-Open No. 8-203035. This magnetoresistance film is intended to enhance the soft-magnetic characteristic of its free magnetic layer to thereby increase the magneto-resistance change rate in a low magnetic field and also improve the heat resistance.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to provide a magnetoresistance film of a structure using an ordered antiferromagnetic material as its antiferromagnetic layer and using an amorphous magnetic alloy in its fixed magnetic structure portion, which even with a high-temperature heat treatment enables ensuring a sufficiently high magnetoresistance change rate (“MR rate”, hereinafter) as well as obtaining a high heat resistance, and a magnetic read sensor.
Namely, the present invention provides a spin valve type magnetoresistance film and a magnetic read sensor, the magneto-sensitive portion of that is constructed using this magnetoresistance film. In this construction of the present invention, when the fixed magnetic structure portion in the spin valve film has an amorphous magnetic layer, studies have been made of the fact that the joint between this amorphous magnetic layer and a non-magnetic conductive layer has serious effects upon the MR rate and the heat resistance. On the basis thereof, the present invention provides a magnetoresistance film that has been improved in the MR rate and in the heat resistance, and a magnetic read sensor.
To attain the above object, the magnetoresistance film of the present invention has an ordered antiferromagnetic layer, a fixed magnetic structure portion joined thereto, a non-magnetic conductive layer, and a free magnetic layer portion having at least one magnetic layer, the fixed magnetic structure portion having provided therein an amorphous magnetic layer, whereby, by providing a crystalline ferromagnetic intermediate layer in the fixed magnetic structure portion, the amorphous magnetic layer and the non-magnetic conductive layer are joined to each other with this crystalline ferromagnetic intermediate layer existing in between.
Also, the magnetic read sensor according to the present invention has a magneto-sensitive portion, and it is constructed that this magneto-sensitive portion has the magnetoresistance film of the present invention.
As described above, the magnetoresistance film of the present invention has a construction wherein its fixed magnetic structure portion has an amorphous magnetic layer. And by making up a construction wherein the amorphous magnetic layer and the non-magnetic conductive layer are joined to each other with a crystalline ferromagnetic intermediate layer existing in between, it has been confirmed that the MR rate and the heat resistance are improved.
And, the magnetic read sensor of the present invention enhances the magnetic read sensitivity and the heat resistance, accordingly the reliability on itself, by constructing its magneto-sensitive portion with the use of the above-described magnetoresistance film.
REFERENCES:
patent: 5909345 (1999-06-01), Kawawake et al.
patent: 6133732 (2000-10-01), Hayashi
patent: 6181537 (2001-01-01), Gill
patent: 6195240 (2001-02-01), Gill
patent: 6277505 (2001-08-01), Shi et al.
Ishii Satoru
Makino Eiji
Takiguchi Masafumi
Sonnenschein Nath & Rosenthal
Tupper Robert S.
Watko Julie Anne
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