Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-06-02
2004-03-02
Ometz, David L. (Department: 2653)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06700756
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spin-valve thin film magnetic element in which electric resistance is changed with the relation between the direction of pinned magnetization of a pinned magnetic layer and the magnetization direction of a free magnetic layer influenced by an external magnetic field. Particularly, the present invention relates to a spin-valve thin film magnetic element having excellent heat resistance, a thin film magnetic head comprising the spin-valve thin film magnetic element, and a method of manufacturing the spin-valve thin film magnetic element which is capable of easily crossing at right angles the magnetization direction of a free magnetic layer and the magnetization direction of a pinned magnetic layer.
2. Description of the Related Art
Magnetoresistive heads include an AMR (anisotropic magnetoresistive) head comprising an element exhibiting a magnetoresistive effect, and a GMR (giant magnetoresistive) head comprising an element exhibiting a giant magnetoresistive effect. The AMR head comprises an element exhibiting the magnetoresistive effect and having a single layer structure comprising a magnetic material. On the other hand, the GMR head comprises an element having a multilayer structure comprising a lamination of a plurality of materials. Although there are some types of structures that create the giant magnetoresistive effect, a spin-valve thin film magnetic element has a relatively simple structure and exhibits a high rate of change in resistance with a weak external magnetic field.
FIGS. 12 and 13
are sectional views respectively showing the structures of examples of conventional spin-valve thin film magnetic elements, as viewed from the surface side facing a recording medium.
In each of the examples, shield layers are formed above and below the spin-valve thin film magnetic element with gap layers provided therebetween. Namely, a reproducing GMR head comprises the spin-valve thin film element, the gap layers, and the shield layers. A recording inductive head may be mounted on the reproducing GMR head.
The GMR head is provided at the trailing side end of a floating slider together with the inductive head to form a thin film magnetic head, for detecting a recording magnetic field of a magnetic recording medium such as a hard disk or the like.
In
FIGS. 12 and 13
, the movement direction of the magnetic recording medium coincides with the Z direction shown in the drawings, and the direction of a leakage, magnetic field from the magnetic recording medium coincides with the Y direction.
The spin-valve thin film magnetic element shown in
FIG. 12
is a so-called bottom type single spin-valve thin film magnetic element comprising an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer.
The spin-valve thin film magnetic element shown in
FIG. 12
comprises a multilayer film
33
comprising a base layer
31
, an antiferromagnetic layer
22
, a pinned magnetic layer
23
, a nonmagnetic conductive layer
24
, a free magnetic layer
25
and a protecting layer
32
, a pair of hard bias layers (permanent magnet layers)
29
formed on both sides of the multilayer film
33
, and a pair of electrode layers
28
respectively formed on the hard bias layers
29
.
Each of the base layer
31
and the protecting layer
32
comprises a Ta film or the like. The track width Tw is determined by the width dimension of the upper side of the multilayer film
33
.
In general, the antiferromagnetic layer
22
comprises a Fe—Mn alloy film or a Ni—Mn alloy film, each of the pinned magnetic layer
23
and the free magnetic layer
25
comprises a Ni—Fe alloy film, the nonmagnetic conductive layer
24
comprises a Cu film, each of the hard bias layers
29
comprises a Co—Pt alloy film, and each of the electrode layers
28
comprises a Cr film, or a W film.
As shown in
FIG. 12
, magnetization of the pinned magnetic layer
23
is put into a single magnetic domain state in the Y direction (the direction of a leakage magnetic field from the recording medium: the height direction) due to an exchange anisotropic magnetic field with the antiferromagnetic layer
22
, and magnetization of the free magnetic layer
25
is oriented in the direction opposite to the X
1
direction due to the influence of a bias magnetic field from the hard bias layers
29
.
Namely, the magnetization directions of the pinned magnetic layer
23
and the free magnetic layer
25
are set to cross at right angles.
In the spin-valve thin film magnetic element, a sensing current is supplied to the pinned magnetic layer
23
, the nonmagnetic conductive layer
24
and the free magnetic layer
25
from the electrode layers
28
formed on the hard bias layers
29
. The movement direction of the recording medium such as a hard disk or the like coincides with the Z direction. When a leakage magnetic field is applied from the recording medium in the Y direction, the magnetization direction of the free magnetic layer
25
is changed from the direction opposite to the X
1
direction to the Y direction. In the free magnetic layer
25
, the electric resistance is changed (referred to as a magnetoresistive effect) with the relation between the change in the magnetization direction and the pinned magnetization direction of the pinned magnetic layer
23
so that the leakage magnetic field from the recording medium is detected by a change in voltage based on the change in electric resistance.
The spin-valve thin film magnetic element shown in
FIG. 13
is a so-called bottom type single spin-valve thin film magnetic element comprising an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer.
In
FIG. 13
, reference character K denotes a substrate on which an antiferromagnetic layer
22
is formed. Furthermore, a pinned magnetic layer
23
is formed on the antiferromagnetic layer
22
, a nonmagnetic conductive layer
24
is formed on the pinned magnetic layer
23
, and a free magnetic layer
25
is formed on the nonmagnetic conductive layer
24
.
Furthermore, bias layers
26
are formed on the free magnetic layer
25
with a space equal to the track width Tw therebetween, and conductive layers
28
are respectively provided on the bias layers
26
.
The pinned magnetic layer
23
comprises, for example, a Co film, a NiFe alloy film, a CoNiFe alloy film, a CoFe alloy film, or the like.
The antiferromagnetic layer
22
is composed of NiMn.
Each of the bias layers
16
comprises an antiferromagnetic material such as a FeMn alloy having a face-centered cubic disordered crystal structure.
The pinned magnetic layer
23
shown in
FIG. 13
is magnetized by an exchange anisotropic magnetic field produced in the interface with the antiferromagnetic layer
22
due to exchange coupling. The magnetization direction of the pinned magnetic layer
23
is pinned in the Y direction shown in the drawing, i.e., the direction away from the recording medium (the height direction).
The free magnetic layer
25
is magnetized by an exchange anisotropic magnetic field of the bias layers
26
to be put into a single magnetic domain state. The magnetization direction of the free magnetic layer
25
is oriented in the direction opposite to the X
1
direction shown in the drawing, i.e., the direction crossing the magnetization direction of the pinned magnetic layer
23
.
The free magnetic layer
25
is put into the single magnetic domain state by the exchange anisotropic magnetic field of the bias layers
26
, thereby preventing the occurrence of Barkhausen noise.
In the spin-valve thin film magnetic element, when a stationary current is supplied to the free magnetic layer
25
, the nonmagnetic conductive layer
24
and the pinned magnetic layer
23
from the conductive layers
28
to apply, in the Y direction shown in the drawing, a leakage magnetic field from the magnetic recording medium moved in the Z direction, the magnetization direction of the free magnetic layer
25
is changed from the di
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ometz David L.
LandOfFree
Spin-valve thin film magnetic element and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spin-valve thin film magnetic element and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spin-valve thin film magnetic element and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3274368