Stock material or miscellaneous articles – All metal or with adjacent metals – Having magnetic properties – or preformed fiber orientation...
Reexamination Certificate
2000-09-13
2004-04-06
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
All metal or with adjacent metals
Having magnetic properties, or preformed fiber orientation...
C428S640000, C428S668000, C428S680000, C428S681000, C428S156000, C428S692100, C360S324100, C360S324120
Reexamination Certificate
active
06716537
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to spin-valve thin-film elements in which the resistivity is varied by the relationship between the magnetization direction of a pinned magnetic layer and the magnetization direction of a free magnetic layer affected by an external magnetic field. In particular, the present invention relates to a magnetoresistive element which can effectively conduct a detecting current to a multilayered film included therein and a method for making the magnetoresistive element.
2. Description of the Related Art
FIG. 21
is a cross-sectional view at an air bearing surface (ABS) of a conventional magnetoresistive element. This magnetoresistive element is called a spin-valve thin-film element which is one of giant magnetoresistive (GMR) elements using a giant magnetoresistive effect, and detects a recorded magnetic field from magnetic media such as a hard disk.
The spin-valve thin-film element has a multilayered film
10
composed of, from the bottom, a second antiferromagnetic layer
1
, a pinned magnetic layer
2
, a nonmagnetic conductive layer
3
, and a free magnetic layer
4
. The second antiferromagnetic layer
1
is generally composed of an iron-manganese (Fe—Mn) alloy or a nickel-manganese (Ni—Mn) alloy. Each of the pinned magnetic layer
2
and the free magnetic layer
4
is generally composed of a nickel-iron (Ni—Fe) alloy. The nonmagnetic conductive layer
3
is generally composed of copper (Cu).
As shown in
FIG. 21
, the thickness of the free magnetic layer
4
is smaller in both side regions A in the track width direction (X direction in the drawing) than that in the central region B. Ferromagnetic layers
5
formed of, for example, a Ni—Fe alloy are provided on the side regions A.
A pair of first antiferromagnetic layers
6
is formed on the ferromagnetic layers
5
and is separated at an interval of the track width Tw. In conventional technology, the first antiferromagnetic layers
6
are composed of an iridium-manganese (Ir—Mn) alloy or the like. Moreover, conductive layers
7
formed of chromium (Cr) are provided on the first antiferromagnetic layers
6
.
In this spin-valve thin-film element, a lower gap layer
8
is provided under the second antiferromagnetic layer
1
, and an upper gap layer
9
is provided over the conductive layers
7
. The lower gap layer
8
and the upper gap layer
9
are composed of an insulating material such as alumina (Al
2
O
3
).
The magnetization of the pinned magnetic layer
2
is aligned in a single-domain state in the Y direction (the direction of the fringing magnetic field from the recording medium, that is, the height direction) by exchange anisotropic magnetic field between the pinned magnetic layer
2
and the second antiferromagnetic layer
1
. Exchange anisotropic magnetic fields are generated between the ferromagnetic layers
5
and the first antiferromagnetic layers
6
and between the ferromagnetic layers
5
and the free magnetic layer
4
at the side regions A, and magnetize the ferromagnetic layers
5
and the free magnetic layer
4
at the side regions A in the X direction. As a result, the magnetization of the free magnetic layer
4
is affected by the bias magnetic field from the ferromagnetic layers
5
and the free magnetic layer
4
at the side regions A and is aligned in the X direction. Accordingly, the magnetization of the pinned magnetic layer
2
and the magnetization of the free magnetic layer
4
are orthogonal.
In this spin-valve thin-film element, a detecting current which is supplied from the conductive layers
7
via the first antiferromagnetic layers
6
flows in the pinned magnetic layer
2
, the nonmagnetic conductive layer
3
, and the free magnetic layer
4
. The recording medium such as a hard disk moves in the Z direction, and a fringing magnetic field from the recording medium is oriented in the Y direction. This fringing magnetic field changes the magnetization direction of the free magnetic layer
4
from the X direction to the Y direction. The resistivity of the element is varied by the relationship between the variable magnetization direction of the free magnetic layer
4
and the pinned magnetization direction of the pinned magnetic layer
2
. Such a change in resistivity is called a magnetoresistive effect and is detected as a change in voltage. The fringing magnetic field from the recording medium is detected in such a manner.
The magnetoresistive element shown in
FIG. 21
, however, has the following problems. Since the conductive layers
7
are formed on the first antiferromagnetic layers
6
, the detecting current flows in the pinned magnetic layer
2
, the nonmagnetic conductive layer
3
, and the free magnetic layer
4
, via the first antiferromagnetic layers
6
. Since the first antiferromagnetic layers
6
are formed of an antiferromagnetic material such as an Ir—Mn alloy having relatively large resistivity, the detecting current flowing in the multilayered film
10
is reduced.
As described above, the magnetization of the free magnetic layer
4
is oriented in the X direction by the bias magnetic field due to the exchange anisotropic magnetic field which is generated between the ferromagnetic layers
5
and the first antiferromagnetic layers
6
. The free magnetic layer
4
is firmly magnetized in the X direction at boundary regions D near the ferromagnetic layers
5
by the effect of the strong bias magnetic field. Thus, the magnetization of the free magnetic layer
4
is not adequately varied by the external magnetic field.
The boundary regions D, which do not exhibit an adequate change in the magnetization, is called dead regions. Thus, the substantial sensitive region, which exhibits an adequate change in the magnetization by the effect of the external magnetic field and thus has a magnetoresistive effect, is a region of the track width Tw other than the dead regions. As a result, the dead regions significantly decrease the fraction of the detecting current in the sensitive region. Thus, a desired amount of detecting current does not flow in the sensitive region, resulting in the generation of noise and a decrease in read output.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a magnetoresistive element which can effectively conducts a detecting current to a triplelayered film including a free magnetic layer, a nonmagnetic conductive layer, and a pinned magnetic layer and having a magnetoresistive effect and which exhibits improved output characteristics.
It is another object of the present invention to provide a method for making the magnetoresistive element.
According to an aspect of the present invention, a magnetoresistive element comprises a multilayered film comprising a magnetic detecting layer having a magnetoresistive effect, a pair of first antiferromagnetic layers in contact with the magnetic detecting layer of the multilayered film at a predetermined gap in the track width direction, the first antiferromagnetic layers aligning the magnetization direction of the magnetic detecting layer, and a pair of conductive layers in contact with the pair of first antiferromagnetic layers, the pair of conductive layers applying a detecting current to the multilayered film. The first antiferromagnetic layers comprise an antiferromagnetic material having higher resistivity than that of the conductive layers, the conductive layers are superimposed with the corresponding first antiferromagnetic layers and are in contact with the magnetic detecting layer in a range of the predetermined gap, and the distance between the pair of conductive layers defines a track width when the multilayered film detects an external magnetic field.
As described above, the magnetoresistive element of the present invention has the pair of first antiferromagnetic layers in order to align the magnetization direction of the magnetic detecting layer of the multilayered film. The present invention is characterized in that the first antiferromagnetic layers comprise an antiferromagnetic material ha
Alps Electric Co. ,Ltd.
Bernatz Kevin M.
Thibodeau Paul
LandOfFree
Magnetoresistive element having multilayered film capable 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 Magnetoresistive element having multilayered film capable of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetoresistive element having multilayered film capable of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3212283