Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2000-01-25
2003-03-25
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06538858
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spin-valve thin film element in which electric resistance changes depending upon the relation between the fixed magnetization direction of a pinned magnetic layer and the magnetization direction of a free magnetic layer affected by an external magnetic field, and a method of manufacturing the thin film element. Particularly, the present invention relates to a spin-valve thin film element with excellent stability in which the magnetic domain of a free magnetic layer can be sufficiently controlled, and a method of manufacturing the thin film element.
2. Description of the Related Art
FIG. 15
is a perspective view showing an example of thin film magnetic heads.
This thin film magnetic head is a floating type which is mounted on a magnetic recording medium such as a hard disk device or the like. In the slider
251
of the thin film magnetic head shown in
FIG. 15
, the side
235
which faces the upstream side in the moving direction of the disk surface is the leading side, and side
236
is the trailing side. In the surface of the slider
251
which faces the disk are formed rail-shaped ABS (air bearing surfaces: the floating surfaces of the rails)
251
a
and
251
b
, and air grooves
251
c.
Furthermore, a magnetic core
250
is provided on the end surface
251
d
on the trailing side of the slider
251
.
The magnetic core
250
of the thin film magnetic head of this example is a combination type magnetic head having the structure shown in
FIGS. 16 and 17
, in which a MR head (reading head) h
1
and an inductive head (writing head) h
2
are laminated in turn on the trailing side-end surface
251
d of the slider
251
.
In this example, the MR head h
1
comprises a lower shielding layer
253
made of a magnetic alloy and formed on the trailing side end of the slider
251
serving as a substrate, and a lower gap layer
254
provided on the lower shielding layer
253
. A magnetoresistive element layer
245
is laminated on the lower gap layer
254
, and an upper gap layer
256
is formed on the magnetoresistive element layer
245
. An upper shielding layer
257
is formed on the upper gap layer
256
so that the upper shielding layer
257
also serves as a lower core layer of the inductive head h
2
provided thereon.
The MR head h
1
causes a change in resistance of the magnetoresistive element layer
145
according to the presence of a small leakage magnetic field from a magnetic recording medium such as a disk of a hard disk device or the like to read the recording content of the recording medium by reading the change in resistance.
The inductive had h
2
comprises a gap layer
264
formed on the lower core layer
257
, and a coil layer
266
having a spiral planar pattern. The coil layer
266
is surrounded by a first insulating material layer
267
A and a second insulating material layer
267
B. An upper core layer
268
is formed on the second insulating material layer
267
B so that the pole end
268
a
thereof is opposed to the lower core layer
257
with a magnetic gap G therebetween in the ABS
251
b
, the base end
268
b
being provided to be magnetically connected to the lower core layer
257
, as shown in
FIGS. 16 and 17
.
A protecting layer
269
made of alumina or the like is provided on the upper core layer
268
.
In the inductive head h
2
, a recording current is supplied to the coil layer
266
to apply the recording current to the core layer from the coil layer
266
. The inductive head h
2
records magnetic signals on the magnetic recording medium such as a hard disk or the like by a leakage magnetic field from the magnetic gap G between the lower core layer
257
and the distal end of the upper core layer
268
.
The magnetoresistive element layer
245
provided in the MR head h
1
comprises a GMR (Giant Magnetoresistive) element exhibiting giant magnetoresistance. The GMR element has a multilayer structure formed by combining a plurality of materials. There are several types of structures creating giant magnetoresistance. Of these types, a type having a relatively simple structure and exhibiting a high rate of change in resistance with an external magnetic field is a spin valve system. The spin valve system includes a single spin valve system, and a dual spin valve system.
FIG. 18
is a sectional view showing the structure of a principal portion of an example of thin film magnetic heads comprising a conventional spin-valve thin film element, as viewed from the side opposite to a recording medium.
In
FIG. 18
, reference numeral MR
1
denote s a spin-valve thin film element. The spin-valve thin film element MR
1
is a top type single spin valve thin film element in which a free magnetic layer
125
, a nonmagnetic conductive layer
124
, a pinned magnetic layer
123
, and an antiferromagnetic layer
122
are formed in turn from the lower gap layer
254
side.
In
FIG. 18
, reference numeral
121
denotes a base layer made of, for example, Ta (tantalum) or the like. The free magnetic layer
125
is formed on the base layer
121
, and the nonmagnetic conductive layer
124
made of Cu or the like is formed on the free magnetic layer
125
. The pinned magnetic layer
123
is formed on the nonmagnetic conductive layer
124
, and the antiferromagnetic layer
122
is further formed on the pinned magnetic layer
123
. A protecting layer
127
made of Ta or the like is formed on the antiferromagnetic layer
122
to form a lamination a
10
.
The pinned magnetic layer
123
is formed in contact with the antiferromagnetic layer
122
to cause an exchange coupling magnetic field (exchange anisotropic magnetic field) in the interface between the pinned magnetic layer
123
and the antiferromagnetic layer
122
, thereby fixing magnetization of the pinned magnetic layer
123
, for example, in the Y direction shown in the drawing.
In addition, hard bias layers
126
made of, for example, a Co—Pt (cobalt-platinum) alloy, i.e., permanent magnet films, are formed on both sides of the free magnetic layer
125
. The hard bias layers
126
are formed for suppressing Barkhausen noise produced due to the formation of a plurality of magnetic domains in the free magnetic layer
125
, and putting the free magnetic layer into a single magnetic domain state. For example, when the hard bias layers
126
are magnetized in the X
1
direction shown in the drawing, magnetization of the free magnetic layer
125
is oriented in the X
1
direction shown in the drawing by a leakage magnetic flux from the hard bias layers
126
. This creates the relation that variable magnetization of the free magnetic layer
125
and fixed magnetization of the pinned magnetic layer
123
cross each other.
In
FIG. 18
, reference numeral
128
denotes a conductive layer made of Cr, Ta, Au, or the like.
In the spin-valve thin film element MR
1
, when the magnetization direction X
1
of the free magnetic layer
125
is changed, electric resistance is changed with the angle with respect to the magnetization direction of the pinned magnetic layer
123
which is fixed in the Y direction, and a leakage magnetic field from the recording medium is detected by a change in voltage based on the change in the electric resistance value.
The central portion of the lamination a
10
lies in a sensitive region which contributes to reproduction of a recording magnetic field from the magnetic recording medium, and which exhibits magnetoresistance, and defines the detection track width Tw.
FIG. 22
is a sectional view showing the structure of a principal portion of another example of thin film magnetic heads comprising another conventional spin valve thin film element, as viewed from the side opposite to a recording medium.
In
FIG. 22
, reference numeral MR
2
denotes a spin-valve thin film element. The spin-valve thin film element MR
2
is different from the spin-valve thin film element MR
1
shown in
FIG. 18
in that an antiferromagnetic layer
122
, a pinned magnetic layer
153
, a nonmagnetic conductive layer
124
, and a free magnetic layer
1
Hasegawa Naoya
Honda Kenji
Kakihara Yoshihiko
Alps Electric Co. ,Ltd.
Klimowicz William
LandOfFree
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