Stock material or miscellaneous articles – All metal or with adjacent metals – Having magnetic properties – or preformed fiber orientation...
Reexamination Certificate
2001-04-04
2003-12-02
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having magnetic properties, or preformed fiber orientation...
C428S622000, C428S627000, C428S629000, C428S632000, C428S639000, C428S641000, C428S668000, C428S667000, C428S670000, C428S678000, C428S692100, C428S690000, C428S900000, C428S928000, C360S112000, C324S252000, C338S03200R
Reexamination Certificate
active
06656604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetoresistive thin-film magnetic element that undergoes a change in electrical resistance in relation to the magnetization vector of a pinned magnetic layer and the magnetization vector of a free magnetic layer affected by an external magnetic field, and to a method for making the same. The present invention also relates to a thin-film magnetic head equipped with the magnetoresistive thin-film magnetic element.
2. Description of the Related Art
FIG. 24
is a perspective view of an exemplary conventional thin-film magnetic head.
This thin-film magnetic head is a floating thin-film magnetic head used with a magnetic recording medium such as a hard disk device. A slider
251
of the thin-film magnetic head has a reading side
235
and a trailing side
236
. Longitudinal air bearing surfaces (ABS)
251
a
and
251
b
and air grooves
251
c
are formed on the surface of the slider
251
facing the disk.
A magnetic core unit
250
is provided on an end face
251
d
of the slider
251
.
The magnetic core unit
250
of this thin-film magnetic head is a composite-type thin-film magnetic head having the structure shown in
FIGS. 25 and 26
, and is formed by successively depositing an MR (read head) h
1
and an inductive head (write head) h
2
on the trailing end face
251
d
of the slider
251
.
The magnetoresistive head h
1
comprises a lower shield layer
253
which is formed on the trailing side portion of the slider
251
and is composed of a magnetic alloy, a lower gap layer
254
formed on the lower shield layer
253
, a magnetoresistive thin-film magnetic element layer
245
formed on the lower gap layer
254
, an upper gap layer
256
formed on the magnetoresistive thin-film magnetic element layer
245
, and an upper shield layer
257
formed on the upper gap layer
256
. The upper shield layer
257
also serves as a lower core layer of the inductive head h
2
formed thereon.
The MR head reads the information stored in the recording medium by detecting a change in resistance at the magnetoresistive thin-film magnetic element layer
245
occurred in response to a weak leakage magnetic field from the magnetic recording medium such as a disk in a hard disk device.
The inductive head h
2
includes a lower core layer
257
, a gap layer
264
formed on the lower core layer
257
, and a coil layer
266
patterned in a spiral. The coil layer
266
is surrounded by a first insulation layer
267
A and a second insulation layer
267
B. An upper core layer
268
is formed on the second insulation layer
267
B. At the air bearing surface
251
b
, a magnetic pole end portion
268
a
of the upper core layer
268
is arranged to face the lower core layer
257
with a magnetic gap G therebetween. As shown in
FIGS. 25 and 26
, a base end portion
268
b
of the upper core layer
268
is magnetically connected to the lower core layer
257
.
A protective layer
269
composed of alumina or the like is provided on the upper core layer
268
.
In this inductive head h
2
, a recording current flows to the coil layer
266
and from the coil layer
266
to the core layers. The inductive head h
2
writes magnetic signals onto a magnetic recording medium such as a hard disk by using a leakage magnetic field provided from the end portions of the lower core layer
257
and upper core layer
268
at the magnetic gap G.
A giant magnetoresistive element (GMR element) or the like is provided in the magnetoresistive thin-film magnetic element layer
245
. The GMR element has a multi-layer structure using a combination of several different materials. Among structures which generate giant magnetoresistive effects, a spin-valve type which is relatively simple in structure while achieving a high rate of change in resistance, is known in the art. There are a single spin-valve type and dual spin-valve type in the spin-valve type.
FIG. 27
is a cross-sectional view of a principal portion of an exemplary thin-film magnetic head MR
2
equipped with a conventional spin-valve thin-film magnetic element, viewed from the side facing a recording medium.
The spin-valve thin-film magnetic element MR
2
is a bottom-type single spin-valve thin-film magnetic element comprising an antiferromagnetic layer
122
, a pinned magnetic layer
153
, a nonmagnetic conductive layer
124
, and a free magnetic layer
165
, deposited in that order from the bottom.
In
FIG. 27
, a composite all has a substantially trapezoidal shape and includes an underlayer
121
comprising Ta or the like, the antiferromagnetic layer
122
composed of a PtMn alloy formed on the underlayer
121
, the pinned magnetic layer
153
formed on the antiferromagnetic layer
122
, the nonmagnetic conductive layer
124
formed on the pinned magnetic layer
153
, the free magnetic layer
165
formed on the nonmagnetic conductive layer
124
, and a protective layer
127
formed on the free magnetic layer
165
. The antiferromagnetic layer
122
extends to the region corresponding to the two lateral portions of the pinned magnetic layer
153
, the nonmagnetic conductive layer
124
, and the free magnetic layer
165
.
The pinned magnetic layer
153
is composed of a nonmagnetic interlayer
154
, a first pinned magnetic sublayer
155
, and a second pinned magnetic sublayer
156
, the latter two sandwiching the nonmagnetic interlayer
154
. The first pinned magnetic sublayer
155
is provided at the position closer to the antiferromagnetic layer
122
than is the nonmagnetic interlayer
154
, and the second pinned magnetic sublayer
156
is provided at the position closer to the nonmagnetic conductive layer
124
than is the nonmagnetic interlayer
154
.
The first pinned magnetic sublayer
155
and the second pinned magnetic sublayer
156
comprise elemental Co, a CoFe alloy, a NiFe alloy, or the like. The nonmagnetic interlayer
154
comprise a nonmagnetic material such as Ru.
Preferably, the thickness of the first pinned magnetic sublayer
155
and the thickness of the second pinned magnetic sublayer
156
are different from each other. In
FIG. 27
, the thickness of the second pinned magnetic sublayer
156
is greater than the thickness of the first pinned magnetic sublayer
155
.
An exchange coupling magnetic field (exchange anisotropic magnetic field) is generated at the interface between the first pinned magnetic sublayer
155
and the antiferromagnetic layer
122
. The magnetization vector of the first pinned magnetic sublayer
155
is pinned in the direction opposite to the Y direction in the drawing by the exchange coupling magnetic field with the antiferromagnetic layer
122
. The second pinned magnetic sublayer
156
antiferromagnetically couples with the first pinned magnetic sublayer
155
so as to pin the magnetization vector of the second pinned magnetic sublayer
156
in the Y direction.
Since the magnetization vectors of the first pinned magnetic sublayer
155
and the second pinned magnetic sublayer
156
are antiparallel to each other, magnetic moments of the first pinned magnetic sublayer
155
and the second pinned magnetic sublayer
156
cancel out. However, because the thickness of the second pinned magnetic sublayer
156
is greater than the thickness of the first pinned magnetic sublayer
155
, the spontaneous magnetization of the second pinned magnetic sublayer
156
slightly remains thereby putting the pinned magnetic layer
153
in a ferri-magnetic state. Moreover, the slight spontaneous magnetization further intensifies the exchange coupling magnetic field with the antiferromagnetic layer
122
, pinning the magnetization vector of the pinned magnetic layer
153
in the Y direction in the drawing.
The free magnetic layer
165
includes an antiferromagnetic layer
166
comprising a ferromagnetic material such as a NiFe alloy and an anti-diffusion layer
167
composed of a ferromagnetic material such as Co. The anti-diffusion layer
167
is provided on the nonmagnetic conductive layer
124
.
Hard bias layers
126
comprising a Co—Pt-type alloy, i.e., permanent ma
Alps Electric Co. ,Ltd.
Kiliman Leszek
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