Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
2001-06-14
2004-05-04
Klimowicz, William (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
Reexamination Certificate
active
06731479
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spin-valve thin-film magnetic element in which electrical resistance changes due to the relationship between the pinned magnetization direction of a pinned magnetic layer and the magnetization direction of a free magnetic layer which is influenced by an external magnetic field, to a method for fabricating the same, and to a thin-film magnetic head provided with the spin-valve thin-film magnetic element. More particularly, the invention relates to a technique applicable to a spin-valve thin-film magnetic element, in which the stability of the element is improved, for example, Barkhausen noise is reduced.
2. Description of the Related Art
A spin-valve thin-film magnetic element is one type of giant magnetoresistive (GMR) element exhibiting a giant magnetoresistance effect, which detects a recorded magnetic field from a recording medium, such as a hard disk.
The spin-valve thin-film magnetic element has a relatively simple structure compared to other GMR elements, and has a high rate of resistance change relative to changes in an external magnetic field, and thus the resistance changes in response to a weak magnetic field.
FIG. 15
is a sectional view of a conventional spin-valve thin-film magnetic element, viewed from a surface (air bearing surface; ABS) facing a recording medium.
The spin-valve thin-film magnetic element shown in
FIG. 15
is a so-called “bottom-type” single spin-valve thin-film magnetic element in which an underlying layer
106
, an antiferromagnetic layer
101
, a pinned magnetic layer
102
, a nonmagnetic conductive layer
103
, a free magnetic layer
104
, and a protective layer
107
are formed in that order on a substrate.
For the spin-valve thin-film magnetic element, a magnetic recording medium, such as a hard disk, travels in the Z direction in the drawing, and a fringing magnetic field from the magnetic recording medium is directed in the Y direction.
The conventional spin-valve thin-film magnetic element shown in
FIG. 15
includes a laminate
109
in which the underlying layer
106
, the antiferromagnetic layer
101
, the pinned magnetic layer
102
, the nonmagnetic conductive layer
103
, the free magnetic layer
104
, and the protective layer
107
are deposited in that order on the substrate; bias layers
105
formed on both sides of the laminate
109
with bias underlying layers
110
therebetween; and electrode layers
108
formed on the bias layers
105
.
The underlying layer
106
is composed of Ta or the like, and the antiferromagnetic layer
101
is composed of an Ni—O alloy, an Fe—Mn alloy, an Ni—Mn alloy, or the like. The pinned magnetic layer
102
and the free magnetic layer
104
are composed of Co, a Co—Fe alloy, an Fe—Ni alloy, or the like, the nonmagnetic conductive layer
103
is composed of Cu or the like, the bias layers
105
are composed of a Co—Pt alloy or the like, the bias underlying layer
110
is composed of Cr or the like, and the electrode layers
108
are composed of Cu or the like.
Since the pinned magnetic layer
102
is formed in contact with the antiferromagnetic layer
101
, an exchange coupling magnetic field (exchange anisotropic magnetic field) is produced at the interface between the pinned magnetic layer
102
and the antiferromagnetic layer
101
, and the pinned magnetization of the pinned magnetic layer
102
is pinned, for example, in the Y direction in the drawing.
Since the bias layers
105
are magnetized in the X
1
direction in the drawing, the variable magnetization of the free magnetic layer
104
is aligned in the X
1
direction. Thereby, the variable magnetization of the free magnetic layer
104
and the pinned magnetization of the pinned magnetic layer
102
are perpendicular to each other.
In the spin-valve thin-film magnetic element, a sensing current is applied from the electrode layers
108
formed on the bias layers
105
to the free magnetic layer
104
, the nonmagnetic conductive layer
103
, and the pinned magnetic layer
102
. A magnetic recording medium, such as a hard disk, travels in the Z direction in the drawing, and when a fringing magnetic field from the magnetic recording medium is applied in the Y direction, the magnetization direction of the free magnetic layer
104
is rotated from the X
1
direction to the Y direction. Due to the relationship between the varied magnetization direction of the free magnetic layer
104
and the pinned magnetization direction of the pinned magnetic layer
102
, the electrical resistance changes, which is referred to as a magnetoresistance (MR) effect, and the fringing magnetic field from the magnetic recording medium is detected by a voltage change based on the change in the electrical resistance.
The central section sandwiched between the electrode layers
108
corresponds to a sensitive region
104
a
which substantially contributes to reading of the recorded magnetic field from the magnetic recording medium, and exhibits the magnetoresistance effect, and which also defines the detection track width Tw. Both end sections of the free magnetic layer
104
correspond to insensitive regions
104
b
which do not greatly contribute to reading of the recorded magnetic field from the magnetic recording medium.
FIG. 16
is a sectional view of another conventional spin-valve thin-film magnetic element, viewed from a surface (ABS) facing a recording medium.
The spin-valve thin-film magnetic element shown in
FIG. 16
is a so-called “top-type” single spin-valve thin-film magnetic element in which a protective layer
117
, an antiferromagnetic layer
111
, a pinned magnetic layer
112
, a nonmagnetic conductive layer
113
, a free magnetic layer
114
, and an underlying layer
116
are deposited in a manner similar to that of the bottom-type single spin-valve thin-film magnetic element described above, but in reversed order.
For the spin-valve thin-film magnetic element, a magnetic recording medium, such as a hard disk, travels in the Z direction in the drawing, and a fringing magnetic field from the magnetic recording medium is directed in the Y direction.
As shown in
FIG. 16
, the free magnetic layer
114
is formed on the underlying layer
116
, the nonmagnetic conductive layer
113
is formed on the free magnetic layer
114
, the pinned magnetic layer
112
is formed on the nonmagnetic conductive layer
113
, and the antiferromagnetic layer
111
is formed on the pinned magnetic layer
112
. The protective layer
117
is formed further on the antiferromagnetic layer
111
.
Reference numeral
120
represents a bias underlying layer, reference numeral
115
represents a bias layer, reference numeral
118
represents an electrode layer, and reference numeral
119
represents a laminate.
In the spin-valve thin-film magnetic element, the magnetization direction of the pinned magnetic layer
112
is pinned in a direction opposite to the Y direction.
The underlying layer
116
is composed of Ta or the like, the antiferromagnetic layer
111
is composed of an Ni—O alloy, an Fe—Mn alloy, an Ni—Mn alloy, or the like. The pinned magnetic layer
112
and the free magnetic layer
114
are composed of Co, an Co—Fe alloy, an Fe—Ni alloy, or the like, the nonmagnetic conductive layer
113
is composed of Cu or the like, the bias layers
115
are composed of a Co—Pt alloy or the like, the bias underlying layers
120
are composed of Cr or the like, and the electrode layers
118
are composed of Cu or the like.
The electrode layers
118
are formed on the bias layers
115
, and the central section sandwiched between the electrode layers
118
corresponds to a sensitive region
114
a
which substantially contributes to reading of the recorded magnetic field from the magnetic recording medium, and exhibits the magnetoresistance effect, and which also defines the detection track width Tw. Both end sections other than the central section sandwiched between the electrode layers correspond to insensitive regions
114
b
which do not greatly contribute to reading of the recorded magnetic f
Hasegawa Naoya
Ooshima Masahiro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Klimowicz William
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