Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1998-06-10
2001-06-05
Klimowicz, William (Department: 2754)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C360S319000, C360S320000
Reexamination Certificate
active
06243241
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spin valve magneto-resistance effect head for reading out the information stored in a magnetic storage medium by utilizing the magneto-resistance effect of a spin valve film. Further, the present invention relates to a magnetic storage apparatus using one or more spin valve magneto-resistance effect heads according to the present invention.
2. Description of the Related Art
In recent information processing apparatuses, for example, personal computers and others, the throughput of the apparatus is considerably improved so that a large quantity of multimedia data, such as sound data, animation data, etc., can be processed at very high speed. In order to provide a large throughput, it is required to realize a magnetic storage apparatus which can freely store and read a large quantity of information, for example, from several ten Giga bytes to several hundred Giga bytes, and which can be made at a low manufacturing cost.
On the other hand, a giant magneto-resistance (GMR) effect head is provided in order to reproduce high density data which are recorded in the magnetic storage medium in the magnetic disk apparatus. Particularly, a spin valve magneto-resistance effect head has a simplified structure, and has a high sensitivity, i.e., change of resistivity, for very small magnetic field. In general, the magneto-resistance effect can be expressed by change of resistivity in response to the magnetic field. That is, this head can convert the change of the signal magnetic field generated by the magnetic storage medium to a change in resistivity. The GMR effect head can provide very large read signal.
Accordingly, research and development of the spin valve magneto-resistance effect head have been performed in many manufacturing firms in order to put this type of head into practical use in magnetic storage apparatuses.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide a spin valve magneto-resistance effect head which can realize stable characteristics over a wide range of temperatures without large change in the structure of the head compared to the conventional art.
Another object of the present invention is to provide a magnetic storage apparatus using the spin valve magneto-resistance effect head according to the present invention.
In accordance with one aspect of the present invention there is provided a spin valve magneto-resistance effect head which includes:
a spin valve film formed by a non-magnetic layer, a pinned layer, a free layer and an antiferromagnetic layer, the non-magnetic layer consisting of non-magnetic substance, the pinned layer consisting of magnetic substance and formed to one surface of the non-magnetic layer, the free layer consisting of magnetic substance and formed to the other surface of the non-magnetic layer, and the antiferromagnetic layer formed to the other surface of the pinned layer, wherein change of resistivity based on giant magneto-resistance effect for a signal magnetic field applied from a storage medium is output from the spin valve film as voltage drop in response to a sense current applied from the outside;
a pair of magnetic shield members each of which is arranged opposite to each surface of the spin valve film for magnetically shielding the spin valve film from a magnetic field applied from the outside except for the signal magnetic field; and
a gap isolation member arranged between the spin valve film and the pair of magnetic shield members for setting the relative position therebetween in order to form a predetermined gap having non-conductivity therebetween;
wherein the antiferromagnetic layer is provided in order to magnetize the pinned layer in a direction orthogonal to the direction of the sense current by forming a magnetic field by an exchange coupling to the pinned layer; and
the support member supports the spin valve film so as to be arranged to a position deflected to one side of the magnetic shield member in such a way that the direction of leakage magnetic field applied to the spin valve film in accordance with magnetic field formed by the sense current has a component of magnetization in the direction of the pinned layer.
In accordance with another aspect of the present invention there is provided a spin valve magneto-resistance effect head which includes:
a spin valve film formed by a non-magnetic layer, a pinned layer, a free layer and an antiferromagnetic layer, the non-magnetic layer consisting of non-magnetic substance, the pinned layer consisting of magnetic substance and formed on one surface of the non-magnetic layer, the free layer consisting of magnetic substance and formed on the other surface of the non-magnetic layer, and the antiferromagnetic layer formed on the other surface of the pinned layer, wherein change of resistivity, based on the giant magneto-resistance effect, for signal magnetic field applied from a storage medium is output from the spin valve film as voltage drop in response to sense current applied from the outside;
a pair of magnetic shield members each of which is arranged opposite to each surface of the spin valve film for magnetically shielding the spin valve film from a magnetic field applied from the outside except for the signal magnetic field; and
a gap isolation member arranged between the spin valve film and the pair of magnetic shield members for setting the relative position therebetween in order to form a predetermined gap having non-conductivity therebetween;
wherein the antiferromagnetic layer is provided in order to magnetize the pinned layer to a direction orthogonal to the direction of the sense current by forming a magnetic field by the exchange coupling to said pinned layer; and
one magnetic shield member, in which the direction of leakage magnetic field applied to the spin valve film in accordance with magnetic field formed by the sense current has a component of magnetization direction of the pinned layer and has a relative magnetic permeability larger than that of the other magnetic shield member.
In a preferred embodiment, one magnetic shield member in the pair of magnetic shield members is the magnetic shield member in which the direction of the leakage magnetic field applied to the spin valve film has a component in the direction of the magnetic field formed by the sense current.
In another preferred embodiment, the pinned layer includes first and second pinned layers both consisting of the magnetic substance, and a relative distance (D
1
) between one surface of the second pinned layer and one magnetic shield member (
110
-
1
) is smaller than the relative distance (D
2
) between the same surface of the second pinned layer and the other magnetic shield member (
110
-
2
).
In still another embodiment, the spin valve film is formed by laminating the following layers in order. The layers include a capping layer (CL), a second free layer (SFL), a first free layer (FFL), a non-magnetic layer (NML), a second pinned layer (SPL), a first pinned layer (FPL), and an antiferromagnetic layer (AFM
1
); and both output terminals (
51
-
1
,
51
-
2
) are provided from the second free layer through the capping layer.
In accordance with still another aspect of the invention, there is provided a magnetic storage apparatus having one or more spin valve magneto-resistive effect heads defined by claims
1
to
7
, including:
a head supporting unit for supporting the heads in a floating state above surface of each magnetic storage medium which stores previously recorded information and position information, one of the recorded information and position information or both being read by the heads;
a servo control unit for reading the position information from the magnetic storage medium through one or any one of the heads, and for performing the positioning of one or all of the heads based on the position information; and
a read unit for reading the recorded information from the magnetic storage medium through one or more heads positioned by the servo control unit.
REFERENC
Fujitsu Limited
Greer Burns & Crain Ltd
Klimowicz William
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