JP2800497B2 - Magnetoresistive head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferromagnetic magnetoresistive element (hereinafter abbreviated as "MR element") for reading magnetic information written in a magnetic storage medium by utilizing a ferromagnetic magnetoresistance effect.
The present invention relates to a magnetoresistive head (hereinafter, abbreviated as an MR head) having the following.

[0002]

2. Description of the Related Art As is well known, an MR element can obtain a high output and the output does not depend on the relative speed between the element and a recording medium. Therefore, application to a reproducing head of a small and high-density magnetic recording apparatus is expected. ing. However, in order to put the MR element into practical use as a signal reproducing head for magnetic recording, it is necessary to satisfy two basic requirements.

The first point is that the MR element has a linear response to a magnetic state written in a magnetic storage medium. For this reason, the MR head is orthogonal to the sense current so that the angle θ (hereinafter, referred to as a bias angle) between the sense current I flowing through the MR element and the magnetization M of the MR element is set to a predetermined value (preferably 45 degrees). It is necessary to apply a bias magnetic field in the direction (hereinafter, referred to as a lateral bias magnetic field). Various methods have been disclosed as the bias means described above. U.S. Pat. No. 3,864,751 discloses a structure in which a soft magnetic bias auxiliary layer and an MR element are laminated with an insulating layer interposed therebetween. This discloses a method in which a sense current is supplied to an MR element to magnetize a soft magnetic bias auxiliary layer, and a lateral bias magnetic field is applied to the MR element by a magnetic field generated by the soft magnetic bias auxiliary layer. As another bias means, Japanese Utility Model Laid-Open No. 60-159518 discloses a structure in which an amorphous soft magnetic bias auxiliary layer and an MR element are laminated with a nonmagnetic conductor layer interposed therebetween. In this configuration, since the specific resistance of the amorphous hard magnetic bias auxiliary layer is significantly higher than the specific resistance of the MR element, most of the sense current flows through the MR element, and the amorphous soft magnetic bias auxiliary A bias effect equivalent to the configuration in which the layer and the MR element are insulated is obtained. Further, in this bias method, it is not necessary to maintain the insulation between the amorphous soft magnetic bias auxiliary layer and the MR element, so that a compact MR head having a thin nonmagnetic conductor layer is formed.

[0004] The second point is to suppress Barkhausen noise, which is a main cause of noise in the reproduced signal and reduces the reproducibility of the reproduced signal. It is considered that the cause of Barkhausen noise is the movement of the domain wall caused by the demagnetizing field at the end of the MR element. For this reason, many methods have been proposed for eliminating the domain wall by forming the MR element portion into a single magnetic domain. Japanese Patent Application Laid-Open No. 62-40610 discloses a structure in which an antiferromagnetic material is placed at both ends of an MR element and a bias magnetic field (hereinafter referred to as a vertical bias magnetic field) is applied in the sense current direction by exchange interaction of the antiferromagnetic material. Is disclosed (FIG. 2).
2A is a cross-sectional view, and FIG. 2B is a plan view.
In these figures, 1 is a nonmagnetic substrate, 2 is a bias auxiliary layer, 3 is a nonmagnetic intermediate layer, 4 is a magnetoresistive layer, and 5 is Fe
The Mn layer 6 is an electrode.

[0005]

However, Fe which is widely used as an antiferromagnetic material for a longitudinal bias magnetic field is used.
Since the Mn film is easily corroded, if the FeMn layer 5 is exposed on the medium running surface as shown in FIG. 2 when used as a magnetic head, the FeMn layer is rapidly corroded and the effect of the longitudinal bias is lost. In addition, there is a problem that the characteristics of the magnetic head are significantly deteriorated.

[0006] An object of the present invention is to provide a magnetoresistive head which solves such problems.

[0007]

In order to solve the above problems, in the MR head of the present invention, a ferromagnetic magnetoresistive layer and an electrode for applying a sense current to the connecting ferromagnetic magnetoresistive layer are provided. An antiferromagnetic layer provided in direct contact with the ferromagnetic magnetoresistive layer to generate a bias magnetic field between the ferromagnetic magnetoresistive layer and the sense current in a direction parallel to the sense current by an exchange force; Means for generating a bias magnetic field in a direction perpendicular to the sense current in the ferromagnetic magnetoresistive layer, and a signal magnetic field generated from the magnetic recording medium at a central portion of the ferromagnetic magnetoresistive layer sandwiched between the electrodes. In the magnetoresistive head having a structure for detecting, the antiferromagnetic layer has the same planar structure as the electrode layer at least in the vicinity of the magnetic field detecting portion, and the tip of the magnetic field detecting portion has an electrode.
Characterized in that it protrudes more toward the medium running surface than the layer.
You.

In addition , a ferromagnetic magnetoresistive layer and a connecting ferromagnetic
Electrode for applying a sense current to the magnetoresistive layer
And the ferromagnetic magnetoresistive layer by an exchange force.
To generate a bias magnetic field parallel to the sense current
The anti-magnetic layer provided directly in contact with the ferromagnetic magnetoresistive layer
A ferromagnetic layer, and a sense current applied to the ferromagnetic magnetoresistive layer.
Means for generating a bias magnetic field in the orthogonal direction.
And a central portion of the ferromagnetic magnetoresistive layer sandwiched between the electrodes.
The signal magnetic field generated from the magnetic recording medium in
When the ferromagnetic layer is at least near the magnetic field sensing portion, the electrode layer
And the electrode layer has the same plane structure as the medium running surface.
In a magnetoresistive head with a structure that recedes from
The receding angle of the electrode is 30 degrees or less.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an example of the MR head of the present invention. As shown in FIG. 1A, the sectional structure of this head is such that a bias auxiliary layer 2, a non-magnetic intermediate layer 3, and an MR layer 4 made of a soft magnetic material having a large magnetoresistance effect are formed on an insulating substrate 1 having a smooth surface. , An FeMn layer 5 serving as a vertical bias layer is laminated, an electrode layer 6 is further formed, and finally, an Al ₂ layer is formed.
It has a structure in which protective layers made of O ₃ , SiO _2, etc. are laminated. At this time, as the planar structure of the head, as shown in FIG. 1B, a structure in which an antiferromagnetic layer is arranged below the electrode layer receded from the medium running surface is used. Another head planar structure according to the present invention is shown in FIG. In this case, a structure is used in which the antiferromagnetic layer is disposed below the electrode layer, and the tip of the magnetic field detection portion projects more toward the medium running surface than the electrode layer.

[0010]

The operation of the present invention will be briefly described below. In the MR head of the conventional structure shown in FIG. 2, since the FeMn layer 5 is exposed on the medium running surface, corrosion progresses from that portion, and the head characteristics deteriorate. On the other hand, in the MR head having the structure of the present invention shown in FIG. 1, the FeMn layer 5 is not exposed on the medium running surface and is covered with the protective layer. .

However, when the electrode is retracted or the magnetic field detecting portion protrudes, the magnetic domain structure of the magnetic field detecting portion becomes unstable. FIGS. 3 and 4 show an MR head having a track width of 5 μm and an MR element height of 5 μm.
These are the results of measuring the fluctuation amount of the reproduction waveform when the receding angle of the electrode and the protrusion amount of the magnetic field detection portion are changed, respectively. The electrode receding angle is 30 degrees, and the protrusion amount of the magnetic field detection portion is 1 μm.
, The waveform fluctuation rapidly increases.

FIG. 1 shows a structure in which the electrode layer 6 is exposed on the FeMn layer 5. However, the effect of the present invention does not depend on the order of lamination of the electrode layers, and as shown in FIG. A similar effect can be obtained with a structure in which an MR element is formed on an electrode layer. The effect of the present invention is also effective in a so-called shield type MR head having a structure in which the MR element having the structure shown in FIG. 1 is sandwiched between magnetic shield layers.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Al having a sputtered Al ₂ O ₃ layer formed on the surface
A NiFe layer having a thickness of 1 μm was formed on a ₂ O ₃ —TiC sintered body substrate by electroplating. After this, NiFe
A predetermined photoresist pattern is formed on the layer, and ion etching is performed in an Ar gas atmosphere to obtain a 50 μm × 50 μm.
m was processed into a rectangular shape to form a lower shield. next,
An Al ₂ O ₃ layer having a thickness of 0.2 μm was formed as a lower shield gap layer. A 50 nm thick bias auxiliary layer and a non-magnetic intermediate layer were formed thereon by rf sputtering in an Ar gas using a CoZrMo alloy target.
A 0 nm Ti layer, a 40 nm thick permalloy (Ni 82% -Fe 18% wt%) layer serving as an MR element, and a 20 nm thick FeMn layer serving as a vertical bias layer were sequentially laminated.
Thereafter, a predetermined photoresist pattern is formed on the laminate, and ion etching is performed in an Ar gas atmosphere.
The FeMn layer was partially patterned. Next, an electrode layer for supplying a sense current to the above-mentioned laminate was formed using a laminate film of Ti and Au. Further, a predetermined photoresist pattern was formed on the laminate, ion etching was performed in an Ar gas atmosphere to determine the outer shape, and then a part of the electrode was removed by chemical etching to form a magnetic field detecting portion. At this time, four types of shapes A, B, C, and D shown in FIG. 6 were used. In each case, the electrode interval corresponding to the track width was 5 μm, and the height of the MR element was 5 μm. The receding angles of the electrodes B and D were 15 degrees, and the protrusion amounts of C and D were 1 μm. On top of this, 0.2 μm thick Al ₂ O ₃
A layer was formed to form an upper shield gap layer. Further, the thickness is 1 μm, 50 μm × 50 μm by frame plating.
An m-rectangular NiFe layer was formed and used as an upper shield. Finally, an Al ₂ O ₃ protective layer having a thickness of 3 μm was formed.

The above MR head is heated at a temperature of 80.degree.
An environmental test was performed by maintaining the device in a high-temperature, high-humidity environment with a relative humidity of 80% for 10 days, and the regenerating characteristics before and after the test were evaluated.

As is clear from Table 1, the MR head having the structure of the present invention shows no Barkhausen noise even after the environmental test, and has excellent performance.

[0016]

[Table 1]

[0017]

According to the present invention, there is provided a magnetoresistive head including a ferromagnetic magnetoresistive layer, an electrode for applying a sense current to the connecting ferromagnetic magnetoresistive layer, and the ferromagnetic magnetoresistive layer. An antiferromagnetic layer provided in direct contact with the ferromagnetic magnetoresistive layer to generate a bias magnetic field in a direction parallel to the sense current by the exchange force; Means for generating a bias magnetic field in a direction, wherein the magnetoresistive head has a structure for detecting a signal magnetic field generated from a magnetic recording medium at a central portion of the ferromagnetic magnetoresistive layer sandwiched between the electrodes. the antiferromagnetic layer has the same planar structure as that of the electrode layer is at least a magnetic field sensing portion near and the magnetic field sensing
The tip of the part protrudes more toward the medium running surface than the electrode layer
The use of the structure has an effect of being excellent in environmental protection and eliminating Barkhausen noise.
In addition, the ferromagnetic magnetoresistive layer and the connecting ferromagnetic magnetoresistive effect
An electrode for applying a sense current to the fruit layer;
The sense current and the flat current are exchanged between the magnetoresistive layer and the magnetoresistive layer.
To generate a bias magnetic field in the row direction, the ferromagnetic
An antiferromagnetic layer provided directly in contact with the resistance layer;
The ferromagnetic magnetoresistive layer is biased in the direction orthogonal to the sense current.
Means for generating an assembling magnetic field.
The magnetic recording medium is located at the center of the sandwiched ferromagnetic magnetoresistive layer.
A signal magnetic field generated from the body, and the antiferromagnetic layer
At least in the vicinity of the magnetic field detection portion, the same planar structure as the electrode layer is used.
And the electrode layer is recessed from the medium running surface.
Angle of the electrode in a magnetoresistive head
By using a structure in which is not more than 30 degrees.
The effect of can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the structure of a magnetoresistive head according to the present invention.

FIG. 2 is a diagram showing a structure of a conventional magnetoresistive head.

FIG. 3 is a diagram showing output fluctuations of a head when an electrode sweep angle is changed.

FIG. 4 is a diagram illustrating output fluctuations of a head when the amount of protrusion of a magnetic field detection portion is changed.

FIG. 5 is a diagram showing a structure of a magnetoresistive head according to the present invention.

FIG. 6 is a diagram showing a structure of a magnetoresistive head according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-magnetic substrate 2 Bias auxiliary layer 3 Non-magnetic intermediate layer 4 Magnetoresistive layer 5 FeMn layer 6 Electrode

Claims (3)

(57) [Claims] 1. An exchange force between a ferromagnetic magnetoresistive layer, an electrode for applying a sense current to a connection ferromagnetic magnetoresistive layer, and the ferromagnetic magnetoresistive layer in a direction parallel to the sense current. An antiferromagnetic layer provided in direct contact with the ferromagnetic magnetoresistive layer to generate a bias magnetic field, and a bias magnetic field generated in the ferromagnetic magnetoresistive layer in a direction orthogonal to a sense current. Means for detecting a signal magnetic field generated from a magnetic recording medium at a central portion of the ferromagnetic magnetoresistive layer sandwiched between the electrodes, wherein the antiferromagnetic layer has at least a magnetic field detecting portion. In the vicinity, it has the same planar structure as the electrode layer,
And a tip of the magnetic field detecting portion protrudes to the medium running surface side from the electrode layer. 2. A ferromagnetic magnetoresistive layer, an electrode for applying a sense current to the connection ferromagnetic magnetoresistive layer, and a direction parallel to the sense current by an exchange force between the ferromagnetic magnetoresistive layer. An antiferromagnetic layer provided in direct contact with the ferromagnetic magnetoresistive layer to generate a bias magnetic field, and a bias magnetic field generated in the ferromagnetic magnetoresistive layer in a direction orthogonal to a sense current. Means for detecting a signal magnetic field generated from a magnetic recording medium at a central portion of the ferromagnetic magnetoresistive layer sandwiched between the electrodes, wherein the antiferromagnetic layer is at least the same as the electrode layer at least in the vicinity of the magnetic field detection portion. A magnetoresistive head, wherein the electrode layer is receded from the medium running surface, wherein the receding angle of the electrode is 30 degrees or less. 3. The magnetoresistive head according to claim 1, wherein the amount of protrusion of the tip of the magnetic field detecting portion is 1.0 μm or less.