Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2003-05-20
2004-09-28
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06798620
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magneto-resistive element, a magnetic head, and a magnetic recording and reproduction apparatus used for magnetic recording or magneto-optic recording, and more specifically to a magneto-resistive element, a magnetic head, and a magnetic recording and reproduction apparatus using a magnetic substrate.
2. Description of the Related Art
Recently, an increase in image information used for digital broadcasting or the like requires a further improvement in the magnetic recording density. Specifically in the field of magnetic heads for use with a magnetic tape, an MIG (metal in gap) head, using a metal magnetic film having a high saturation magnetic flux density in the vicinity of the magnetic gap, is being used more and more widely.
The transfer rate for information recording is now required to be almost 100 MHz. Inductive magnetic heads including an MIG head have a problem that the reproduction capability is significantly reduced as the frequency is increased, due to the loss of eddy current and the limit of ferromagnetic resonance.
In order to overcome this problem, a yoke-type thin film magnetic head using a GMR (gigantic magneto-resistive) element is now under study. The yoke-type thin film magnetic head includes a yoke formed of a high saturation magnetic flux density material and thus has an advantage of a smaller loss at a high frequency.
However, a magnetic head using a thin film magnetic material has a problem of a significantly poor anti-abrasion characteristic when used for a tape medium. The poor anti-abrasion characteristic affects the life of the head.
A head including a yoke formed of a high saturation magnetic flux density material and including a GMR element as a magneto-resistive element has the following problem. A free layer of the GMR element located in a gap in the yoke has a thickness of several nanometers, and thus magnetic saturation is likely to occur. Therefore, a magnetic circuit formed of the yoke has a larger magnetic resistance, and as a result, the efficiency of the head is reduced.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a magneto-resistive element includes a magnetic substrate; a magnetic layer; and a non-magnetic layer provided between the magnetic substrate and the magnetic layer.
In one embodiment of the invention, a relative angle between a magnetization direction of the magnetic substrate and a magnetization direction of the magnetic layer changes in accordance with a change in an external magnetic field.
In one embodiment of the invention, the magnetic substrate includes a free layer in which magnetization rotation with respect to an external magnetic field is possible. The magnetic layer includes a fixed layer in which magnetization rotation with respect to the external magnetic field is more difficult to occur than in the free layer.
In one embodiment of the invention, the magneto-resistive element further includes a hard magnetic layer with a large coercive force provided so as to face the magnetic substrate with the magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided so as to face the magnetic substrate with the magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes a synthetic anti-ferromagnetic layer provided so as to face the magnetic substrate with the magnetic layer interposed therebetween, the synthetic anti-ferromagnetic layer being magnetically coupled with the anti-ferromagnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes a soft magnetic layer with a high saturation magnetic flux density provided between the magnetic substrate and the non-magnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided between the magnetic substrate and the non-magnetic layer.
In one embodiment of the invention, the magnetic substrate contains ferrite.
In one embodiment of the invention, the magnetic substrate contains an oxide.
In one embodiment of the invention, the magnetic substrate contains a single crystalline oxide.
In one embodiment of the invention, the magnetic layer contains magnetite.
In one embodiment of the invention, the magnetic layer contains at least one element selected from the group consisting of O, N, P, C and B.
In one embodiment of the invention, the non-magnetic layer includes a tunnel layer.
In one embodiment of the invention, the non-magnetic layer includes a metal non-magnetic layer.
According to another aspect of the invention, a magneto-resistive element includes a magnetic substrate; a first magnetic layer; a second magnetic layer provided so as to face the magnetic substrate with the first magnetic layer interposed therebetween; and a first non-magnetic layer provided between the first magnetic layer and the second magnetic layer.
In one embodiment of the invention, a relative angle between a magnetization direction of the first magnetic layer and a magnetization direction of the second magnetic layer changes in accordance with a change in an external magnetic field.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are magnetically coupled with each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by ferromagnetic coupling by which a magnetization direction of the magnetic substrate and a magnetization direction of the first magnetic layer are parallel to each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by ferromagnetic coupling by which a magnetization direction of the magnetic substrate and a magnetization direction of the first magnetic layer are anti-parallel to each other.
In one embodiment of the invention, the magnetic substrate and the first magnetic layer are coupled with each other by static magnetic coupling.
In one embodiment of the invention, the magneto-resistive element further includes an underlying layer provided between the magnetic substrate and the first magnetic layer.
In one embodiment of the invention, the underlying layer includes a second non-magnetic layer.
In one embodiment of the invention, the underlying layer includes an anti-ferromagnetic layer.
In one embodiment of the invention, the underlying layer has a thickness in the range of 0.5 nm to 50 nm including 0.5 nm and 50 nm.
In one embodiment of the invention, the first magnetic layer includes a free layer in which magnetization rotation with respect to an external magnetic field is possible. The second magnetic layer includes a fixed layer in which magnetization rotation with respect to the external magnetic field is more difficult to occur than in the free layer.
In one embodiment of the invention, the magneto-resistive element further includes a hard magnetic layer with a large coercive force provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes an anti-ferromagnetic layer provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween.
In one embodiment of the invention, the magneto-resistive element further includes a synthetic anti-ferromagnetic layer provided so as to face the magnetic substrate with the second magnetic layer interposed therebetween, the synthetic anti-ferromagnetic layer being magnetically coupled with the anti-ferromagnetic layer.
In one embodiment of the invention, the magneto-resistive element further includes a soft magnetic layer with a high saturation magnetic flux density provided between the magnetic substrate and the first magnetic layer.
In one embodiment of the invention, the magnetic substrate contains ferrite.
In one embodiment of the invent
Adachi Hideaki
Hiramoto Masayoshi
Iijima Kenji
Matsukawa Nozomu
Odagawa Akihiro
Cao Allen
Renner , Otto, Boisselle & Sklar, LLP
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