JPH07201019A - Magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To suppress a Barkhausen noise without deteriorating reproducing sensitivity and reproducing resolution by providing a domain control layer consisting of a soft magnetic material at a position separated by a prescribed distance from the side plane of both terminals in the longitudinal direction of a magneto-resistance effect fill. CONSTITUTION:An insulating layer 32 consisting of Al2O3, a lower shield layer 29 consisting of Nide alloy, and an insulating layer 31 consisting of Al2O3 are formed on a substrate 33 consisting of Al2O3-TiC sequentially. A magneto- resistance element part 20 is formed on the insulating layer 31, and the element 20 consists of the magneto-resistance effect film 21 and an antimagnetic film 23 consisting of a switched connection control film and 7-Fern alloy. A shunt layer 24 consisting of Mo is formed on the element part 21, and the domain control layers 25, 26 consisting of the soft magnetic material with a high saturation magnetic flux density and with film thickness equal to or slightly thicker than the effect film 21 are formed on the insulating layer 31 separated by distance (1) from the side plane of the effect film 21. The magneto-resistance ratio of the control layers 25, 26 is smaller one to two digits than that of the effect film 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head for converting a magnetic signal into an electric signal by the magnetoresistive effect, and more particularly to a compact and large capacity magnetic recording device such as a magnetic disk device. The present invention relates to a magnetoresistive head.

[0002]

2. Description of the Related Art A magnetoresistive head has attracted attention as a reproducing head for a magnetic disk device or the like, but it has a problem that Barkhausen noise is generated due to the domain wall movement in the magnetoresistive film. As a means for solving this problem, Japanese Patent Publication No. Sho 60-32330 discloses that
It is disclosed that an antiferromagnetic film is formed on the magnetoresistive film. According to this means, the magnetoresistive film becomes a single domain due to exchange coupling between the magnetoresistive film and the antiferromagnetic film, and Barkhausen noise is reduced. However, if the exchange coupling is too strong, the reproduction sensitivity is lowered. The problem arises.

On the other hand, Japanese Patent Laid-Open No. 64-1112 discloses that
It is disclosed that hard magnetic materials are arranged at both ends in the longitudinal direction of the magnetoresistive film. According to this means, the leakage magnetic field from the hard magnetic material causes the magnetoresistive effect film to become a single magnetic domain, and Barkhausen noise is reduced. However, if the leakage magnetic field is too strong, there is a problem that the reproduction sensitivity is lowered. Also,
There is also a problem that this leakage magnetic field adversely affects the signal on the recording medium.

[0004]

DISCLOSURE OF THE INVENTION The present invention reveals the structure of a magnetoresistive head which suppresses the generation of Barkhausen noise without lowering the reproduction sensitivity and does not adversely affect the signal on the recording medium. It is something to do.

[0005]

A magnetoresistive head according to the present invention comprises a magnetoresistive film for converting a magnetic signal into an electric signal by the magnetoresistive effect, and a longitudinal direction of the magnetoresistive film. In a magnetoresistive head including a pair of electrodes for passing a current for signal detection, a magnetic domain control layer made of a soft magnetic material is provided at a position separated by a predetermined distance from the side surfaces at both longitudinal ends of the magnetoresistive film. Is provided.

[0006]

According to the above-mentioned structure of the present invention, the magnetic domain control layer is magnetostatically coupled with the magnetoresistive effect film, and the return domain is easily formed in the magnetic domain control layer. Generation of reflux magnetic domains is suppressed. Further, since the magnetoresistive film and the magnetic domain control layer are separated from each other, the movement of the magnetic domain wall in the magnetic domain control layer does not adversely affect the magnetoresistive film when the signal is reproduced. Therefore, Barkhausen noise can be reduced without lowering the reproduction sensitivity.

Further, the magnetic domain control layer made of a soft magnetic material is
The signal on the recording medium is not adversely affected even if it is exposed to the surface facing the recording medium.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a magnetoresistive head according to an embodiment of the present invention. Referring to FIG.
An insulating layer 32 made of Al ₂ O _{3 having a} thickness of 10 μm, a lower shield layer 29 made of NiFe alloy having a thickness of 1 μm, and Al ₂ O ₃ are formed on the substrate 33 made of l ₂ O ₃ —TiC. The insulating layer 31 having a film thickness of 0.2 μm is sequentially formed. The magnetoresistive effect element portion 20 is formed on the insulating layer 31. The magnetoresistive effect element portion 20 is composed of a magnetoresistive effect film 21 made of NiFe alloy and having a film thickness of 300Å, NiC.
An exchange coupling control film 22 made of a u alloy and having a film thickness of 10Å, and an antiferromagnetic film 2 made of a γ-FeMn alloy and having a film thickness of 150Å.
It is composed of three. The magnetoresistive effect film 21 has uniaxial anisotropy with the longitudinal direction as the easy axis of magnetization, and the uniaxial anisotropy magnetic field is 6 Oe.

On the magnetoresistive effect element portion 21, a chaton layer 24 made of Mo and having a film thickness of 80 Å is formed.
On the insulating layer 31 separated from the side surface of the magnetoresistive film 21 by a distance l, a soft magnetic material having a high saturation magnetic flux density,
Magnetic domain control layers 25 and 26 having the same or slightly thicker film thickness as the magnetoresistive film 21 are formed. In this embodiment, CoZrSn amorphous alloy is used as the material of the magnetic domain control layers 25 and 26, and the film thickness thereof is 300Å. In this case, the uniaxial anisotropic magnetic field of the magnetic domain control layers 25 and 26 is 17 Oe, which is larger than the uniaxial anisotropic magnetic field of the magnetoresistive effect film 21, and the magnetic resistance ratio of the magnetic domain control layers 25 and 26 (hereinafter referred to as MR ratio). (Abbreviated) is 0.1% or less, which is one to two digits smaller than the MR ratio of the magnetoresistive effect film 21.

Mo / Cu is formed on both sides of the shunt layer 24.
/ Mo is composed of 3 layers and the film thickness is 200Å / 10
A pair of electrodes of 00Å / 200Å are formed. The electrode 27 covers the magnetic domain control layer 25 so that the electrode 2
Reference numeral 8 is formed so as to cover the magnetic domain control layer 26. A track portion is formed between the electrodes 27 and 28.

FIG. 2 is a perspective view showing the magnetic domain resistance effect head of the embodiment shown in FIG. As shown in FIG. 2, a film thickness of 0.2 μm made of Al ₂ O ₃ is formed on the electrodes 27 and 28.
An upper shield layer 30 made of a NiFe alloy and having a film thickness of 1 μm is provided via an insulating layer (not shown). In FIG. 2, the magnetic domain control layers 25 and 26 and the lower shield layer are shown.
The insulating layer on the field layer 29 is also omitted in the drawing.

Each layer constituting the magnetoresistive head is sequentially formed on the substrate 33 by a sputtering method or the like and shaped into a predetermined plane shape by an etching method or the like.

The magnetoresistive effect film 21 included in the magnetoresistive effect element portion 20 converts a magnetic signal on the recording medium into an electric signal by the magnetoresistive effect, and the material thereof is other than the above NiFe alloy. Also CoFe alloy, NiC
Alloys such as o are used, and films made of these alloys may be laminated and used.

The antiferromagnetic film 23 included in the magnetoresistive effect element section 20 is provided to give an exchange coupling magnetic field to the magnetoresistive effect film 21, and its material is γ-
In addition to FeMn alloys, FeMn alloys also contain Pd, Pt, I
NiMn, an alloy to which an element of a third component such as r or Er is added
Alloys, CrAl alloys, NiO, etc. are used.

The exchange coupling control film 22 included in the magnetoresistive effect element portion 20 is provided for controlling (weakening and stabilizing) the exchange coupling magnetic field, and the material thereof is the above NiCu alloy or the like. A paramagnetic material having a Curie point of ℃ or less, or a soft magnetic material having a small saturation magnetic flux density such as NiFeNb alloy is used. However, in order to obtain a sufficient effect of controlling the exchange coupling magnetic field with a thin film thickness, it is preferable to use the paramagnetic material.

The magnetoresistive effect element portion 20 is shaped into a planar shape of 150 × 5 μm by an etching method.

Lower shield layer 1 and upper shield layer 5
Is provided in order to prevent an external magnetic field other than the signal magnetic field from being mixed into the magnetoresistive effect element section 10 and to improve the reproduction resolution. As a material thereof, other than the above NiFe alloy, a Co-based amorphous material is used. A soft magnetic material such as a quality alloy is used, and the film thickness is generally 1 to 3 μm.

The electrodes 27 and 28 are the magnetoresistive effect element portion 2.
It is provided to pass a current for signal detection through the magnetoresistive film of 0, and the film thickness is generally 1000 to 2000 Å
Is.

The Chatton film 24 is provided for applying a bias magnetic field to the magnetoresistive effect film element portion 20, and the material thereof is Ti, Nb, T in addition to the above Mo.
a, W, etc. are used, and the film thickness is generally 80 to 1000Å.

FIG. 3 is a plan view showing the result of observing the magnetic domain structure of the magnetoresistive film 21 and the magnetic domain control layers 25 and 26 of the embodiment shown in FIG. 1 by the Bitter method. As shown in FIG. 3, there is no domain wall in the magnetoresistive film 21,
The magnetoresistive film 21 has a single magnetic domain. On the other hand, magnetic domain walls 45 and 46 are generated in the magnetic domain control layers 25 and 26, respectively. This is because the magnetic domain control layers 25 and 26 have domain wall energy
This is because it is composed of a large material.

When reproducing a signal as a magnetoresistive head, the domain walls 45 and 46 in the magnetic domain control layers 25 and 26 move under the influence of the signal magnetic field, but the magnetoresistive element 21.
Is separated from the magnetic domain control layers 25 and 26, the movement of the domain walls 45 and 46 does not cause the generation of a new domain wall in the magnetoresistive effect element 21, and Barkhausen noise does not occur.

FIG. 4 is a plan view showing the magnetic domain structure of the magnetoresistive film when the magnetic domain control layer is not provided. In such a case, the magnetic domain wall 41 is likely to be generated in the magnetoresistive effect film 11, and the magnetic domain wall 41 is easily moved under the influence of the signal magnetic field when reproducing a signal as the magnetoresistive effect type head, and the bulk. Hausen noise is likely to occur.

As can be seen from the above, the Barkhausen noise is suppressed in the magnetoresistive head according to the present invention by providing the magnetic domain control layer.

FIG. 5 is a diagram showing the relationship between the distance l between the magnetoresistive effect film 21 and the magnetic domain control layers 25 and 26 shown in FIG. 1 and the Barkhausen noise occurrence state. In FIG. 5, the vertical axis represents the size of the magnetic domain generated at the end of the magnetic domain resistance effect film, that is, m shown in FIG.

As can be seen from FIG. 5, when the distance l between the magnetoresistive effect film and the magnetic domain control layer is 2 μm or less, no domain wall is generated in the magnetoresistive effect film and the magnetoresistive effect film has a single domain structure. Become. Further, when the distance 1 is 4 μm or less, the magnetic domain size m is 5 μm or less, and Barkhausen noise does not occur.

FIG. 6 is a resistance-magnetic field curve for various magnetoresistive heads, and FIG. 6A shows the magnetoresistive head of the embodiment shown in FIG. 1 (hereinafter referred to as MR head [A]). And (b) is a magnetoresistive head (hereinafter referred to as an MR head) composed of a magnetoresistive element portion having neither an antiferromagnetic film, an exchange coupling control film nor a magnetic domain control layer. (C) is composed of a magnetoresistive effect element portion provided with an antiferromagnetic film in contact with the magnetoresistive effect film and having neither an exchange coupling control film nor a magnetic domain control layer. And a magnetoresistive head (hereinafter abbreviated as MR head [C]). The exchange coupling magnetic field in the MR head [C] is 2
It is 0 Oe or more.

As can be seen from FIG. 6, the MR head [B] has a large maximum resistance change rate (hereinafter, abbreviated as MR ratio) and is excellent in reproducing sensitivity, but Barkhausen noise is generated. . The MR head [C] is excellent in that Barkhausen noise is not generated, but since the MR ratio is small and the optimum bias magnetic field is large,
It is disadvantageous in terms of reproduction sensitivity. On the other hand, in the MR head [A] of the embodiment of the present invention, Barkhausen noise is not generated, the MR ratio is large, and the optimum bias magnetic field is small, so that the reproducing sensitivity is also excellent.

7 to 9 are plan views showing examples of the relative arrangement of the magnetoresistive effect film and the magnetic domain control layer and the planar shape of the magnetic domain control layer in the present invention, and the magnetoresistive effect shown in each figure. The upper edges of the film 21 and the magnetic domain control layers 25 and 26 face the magnetic recording medium.

In the example shown in FIG. 7, the magnetoresistive effect film 21 and the magnetic domain control layers 25 and 26 have substantially the same width. That is, the side surfaces of the magnetic domain control layers 25 and 26 are opposed to the entire width of the side surfaces 21 a at both ends in the longitudinal direction of the magnetoresistive effect film 21.

In the example shown in FIG. 8, the magnetic domain control layers 25 and 26.
Is wider than the magnetoresistive film 21, and the magnetic domain control layer 2
Nos. 5 and 26 project below the magnetoresistive film.
Also in this structure, the magnetic domain control layers 25 and 26 are formed with respect to the entire width of the side surfaces 21a at both ends in the longitudinal direction of the magnetoresistive effect film 21.
The sides are facing each other.

In the example shown in FIG. 9, the magnetic domain control layers 25 and 26.
Is wider than the magnetoresistive effect film 21, and the magnetic domain control layers 25 and 26 project below the magnetoresistive effect film 21 in a direction approaching each other. Also in this structure, the side surfaces of the magnetic domain control layers 25 and 26 face the entire width of the side surfaces 21a at both ends in the longitudinal direction of the magnetoresistive effect film 21.

FIG. 10 and FIG. 11 are plan views showing an unfavorable example of the relative arrangement of the magnetoresistive film and the magnetic domain control layer and the planar shape of the magnetic domain control layer, and the magnetoresistive film shown in each drawing. 21 and the upper side edges of the magnetic domain control layers 25 and 26 face the magnetic recording medium.

In the example shown in FIG. 10, the magnetic domain control layers 25, 2
The width of 6 is narrower than the width of the magnetoresistive effect layer 21. In this case, if there is a portion where the side faces of the magnetic domain control layers 25 and 26 do not face the side faces 21a at both longitudinal ends of the magnetoresistive effect film 21, the effect of the magnetic domain control layer in the present invention is reduced.

In the example shown in FIG. 11, the magnetic domain control layers 25, 2
6 has a sharp side surface, and in this case also, the effect of the magnetic domain control layer in the present invention is reduced.

As can be seen from the above, in order to obtain the effect of the magnetic domain control layer in the present invention, the total width of the side surfaces 21a at both longitudinal ends of the magnetoresistive effect film 21 is
The side surfaces of the magnetic domain control layers 25 and 26 are preferably opposed to each other.

In the above description, the shield type magnetoresistive head of the Chatton bias system is taken as an example, but the present invention is not limited to this, and other types such as the soft bias system and the yoke type are used. The present invention can also be applied to magnetoresistive heads of the type and type.

[0038]

According to the present invention, there is provided a magnetoresistive head which suppresses the generation of Barkhausen noise without lowering the reproduction sensitivity or reproduction resolution.

[Brief description of drawings]

FIG. 1 is a sectional view showing a magnetoresistive head in an embodiment according to the present invention.

FIG. 2 is a perspective view showing a magnetoresistive head of the embodiment shown in FIG.

FIG. 3 is a plan view showing a magnetic domain structure of a magnetoresistive effect film in the example shown in FIG.

FIG. 4 is a plan view showing a magnetic domain structure of a magnetoresistive effect film in a comparative example.

FIG. 5 is a diagram showing the relationship between the distance between the magnetoresistive film and the magnetic domain control layer and the size of the magnetic domain.

FIG. 6 is a resistance-magnetic field curve diagram for various magnetoresistive heads.

FIG. 7 is a plan view showing an example of shapes and arrangements of a magnetoresistive film and a magnetic domain control layer according to the present invention.

FIG. 8 is a plan view showing another example of the shapes and arrangements of the magnetoresistive film and the magnetic domain control layer in the present invention.

FIG. 9 is a plan view showing still another example of the shapes and arrangements of the magnetoresistive film and the magnetic domain control layer in the present invention.

FIG. 10 is a plan view showing shapes and arrangements of a magnetoresistive film and a magnetic domain control layer in a comparative example.

FIG. 11 is a plan view showing shapes and arrangements of a magnetoresistive effect film and a magnetic domain control layer in another comparative example.

[Explanation of symbols]

 27, 28 Electrode 24 Shunt Layer 20 Magnetoresistive Element 21 Magnetoresistive Film 22 Exchange Coupling Control Film 23 Antiferromagnetic Film 25, 26 Domain Control Layer

Claims (8)

[Claims] 1. A magnetoresistive effect film for converting a magnetic signal into an electric signal by the magnetoresistive effect, and a pair of electrodes for passing a current for signal detection in the longitudinal direction of the magnetoresistive effect film. In the magnetoresistive head, the magnetoresistive effect is characterized in that a magnetic domain control layer made of a soft magnetic material is provided at a position separated from the side surfaces at both ends in the longitudinal direction of the magnetoresistive film by a predetermined distance. Mold head. 2. The magnetoresistive head according to claim 1, wherein the magnetic domain control layer is made of a soft magnetic material having a larger uniaxial anisotropic magnetic field than the magnetoresistive film. 3. The magnetoresistive head according to claim 1, wherein the distance between the magnetoresistive film and the magnetic domain control layer is 4 μm or less. 4. The magnetoresistive head according to claim 1, wherein the magnetic domain control layer has side surfaces facing the entire side surfaces at both ends of the magnetoresistive film. 5. The magnetoresistive film, the magnetic domain control layer,
2. The magnetoresistive head according to claim 1, wherein the pair of electrodes are provided between the pair of shield layers. 6. The magnetic material according to claim 1, further comprising an exchange coupling control film provided in contact with the magnetoresistive film and an antiferromagnetic film provided in contact with the exchange coupling control film. Resistance effect type head. 7. The magnetoresistive head according to claim 6, wherein the exchange coupling control film is made of a paramagnetic material. 8. The magnetoresistive head according to claim 6, wherein the exchange coupling control film is made of a soft magnetic material.