JP2861714B2 - Magnetoresistive head and magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head and a magnetic disk drive used for reproducing information recorded on a magnetic medium.

[0002]

2. Description of the Related Art A magnetoresistive head (MR head) is
This head uses the magnetoresistance effect in which the internal resistance changes according to the change in the magnetization direction inside the magnetoresistance effect (MR) film. Generally, an MR head is used by applying two bias magnetic fields. One is called a transverse bias magnetic field and serves to linearize the response to magnetic flux from the magnetic medium. The other is called a longitudinal bias magnetic field, and generates magnetic domains by aligning spin directions in the MR film by magnetic exchange coupling between the MR film and the antiferromagnetic thin film or between the MR film and the permanent magnet film. And works to suppress Barkhausen noise. This antiferromagnetic thin film or permanent magnet film
It is called a magnetic domain control film.

As a magnetic domain control film, FeMn and the like are known, and a structure in which a magnetic domain control film and an electrode film are sequentially laminated on an MR film is adopted as described in JP-A-62-40610.

[0004]

SUMMARY OF THE INVENTION However, FeM
n is a material having poor corrosion resistance. On the other hand, NiO, which is an antiferromagnetic material having high corrosion resistance, has a high electric resistance, so that the structure of the above-mentioned known example cannot be adopted. Further, in a structure in which an MR film is formed on the magnetic domain control film and an electrode film is further laminated, the magnetic domain control film is arranged also in the read track portion, so that spins inside the MR film hardly rotate, Large output cannot be obtained. Further, if the readout track has a structure in which no magnetic domain control film is provided only for the read track, a step occurs in the MR film at the end of the magnetic domain control film, so that the magnetic domain structure becomes unstable and Barkhausen noise occurs.

An object of the present invention, even when a high resistance magnetic domain control film, Barkhausen noise is suppressed, a large reproducing output can be obtained, magnetic to cope with a narrow track
An object of the present invention is to provide a resistance effect type magnetic head and a magnetic disk drive .

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetoresistive film, a magnetic domain control film having a surface magnetically continuous with the magnetoresistive film, and supplying a current to the magnetoresistive film. a pair of electrode films which, in a magnetoresistive head having a means for applying a bias magnetic field to the magnetoresistive film, the electrode film and the read track and the magnetic domain control layer in contact with the magnetoresistive film exchange on both sides of the portion excluding
Are mutually arranged, and characterized by having the magnetoresistive film and the domain control film and <br/> contacts the surface are three or more, the magnetoresistive effect film and the electrode film and the three or more contacts surfaces Is achieved by a magnetoresistive head. The magnetic domain control film is preferably made of NiO.

[0007]

[0008]

[0009]

A non-magnetic thin film having a high electric resistance, the magnetic domain control film and the electrode film are arranged on the magneto-resistive film, and an interface between the magneto-resistive film and the non-magnetic thin film is arranged in a read track portion. May be.

[0011] In an end portion of the magnetoresistive film, the area of the magnetoresistive film and the domain control film are in contact with the surface is larger than the area of the surface and the magnetoresistive effect film and the electrode film is in contact You may.

A non-magnetic thin film having a high electric resistance, the magnetic domain control film and the electrode film are disposed on the magneto-resistive film, and an interface between the magneto-resistive film and the non-magnetic thin film is disposed in a read track portion. May be.

[0013]

[0014] and the magnetoresistive film and the domain control film
The boundary line between the surface and the read track contact, the magnetoresistive film and the electrode film are in contact with the surface and the magnetoresistive film and the boundary between the domain control film are in contact with the surface is a non-parallel Is also good.

A non-magnetic thin film having a high electric resistance, the magnetic domain control film and the electrode film are disposed on the magneto-resistive film, and an interface between the magneto-resistive film and the non-magnetic thin film is disposed in a read track portion. May be.

[0016] The present invention relates to a magnetoresistive head having a magnetoresistive film and the electrode, in a magnetic disk device having a drive unit for rotating the magnetic disk and the magnetic disk, the magnetoresistive head is above Yo
It is characterized by the following.

After an MR film is formed on a flat surface having no steps, a magnetic domain control film and an electrode film are formed. then,
At least the magnetic domain control film is not disposed on the read track portion. Regarding the arrangement of the magnetic domain control film and the electrode film, there are two arrangements, a method of determining the read track width by the magnetic domain control film and a method of determining the read track width by the electrode film, which are the basic structures of the present invention.

As a more practical structure, there is a structure described below. One is (1) a structure in which a non-magnetic thin film having a high electric resistance is arranged on a read track portion of an MR film, and a magnetic domain control film and an electrode film are arranged on both sides thereof.
The other is (2) the arrangement in which the total area of the surface where the MR film and the electrode film are electrically continuous is increased to secure a current path, or (3) the magnetic domain structure of the MR film is widened. This is an arrangement in which the total area of the surface where the MR film and the magnetic domain control film are magnetically continuous is increased in order to control over the entire area. Furthermore, (1) and
The structures of (2), (1) and (3) can be combined.

Further, in a manner that determines the read track width in the magnetic domain control film, the MR film and the boundary between the domain control film are in contact with the surface and read track, MR film and the electrode film and the surface in contact with the MR layer and the magnetic domain By arranging the boundary line with the surface in contact with the control film not parallel, it is also possible to apply a lateral bias magnetic field.

[0020]

In order to suppress Barkhausen noise, M
It is necessary that the R film be in a single magnetic domain state. If there is a step in the MR film, a magnetic pole is formed at the step, which causes a magnetic domain. Therefore, it is desirable that the MR film be flat.
As a method for stabilizing the single magnetic domain state of the MR film, a method of aligning the spin directions inside the MR film using exchange coupling between the magnetic domain control film made of an antiferromagnetic material or a permanent magnet material and the MR film is used. . This exchange coupling makes it difficult for spins inside the MR film to rotate with respect to an external magnetic field. Therefore, in order to obtain a large reproduction output, it is desirable that there is no exchange coupling at least in the read track portion. Further, when a material having high resistance is used as the magnetic domain control film, the MR film and the electrode film need to be in direct electrical contact. In consideration of these facts, as shown in FIG. 1, the MR film and the magnetic domain control film are magnetically continuous in portions other than the read tracks on the surface of the MR film formed on the surface having no step. The structure has a surface and a surface on which the MR film and the electrode film are electrically continuous.

FIG. 2A shows the magnetic domain control film 1 on the MR film 10.
1 is formed, and an electrode film 12 is formed thereon at a predetermined distance. In this case, the electrode film 12 defines the read track width. Since the current flows only in the read track portion, the off-track characteristic is good. However, since the interval between the magnetic domain control films 11 is wide, Barkhausen noise is likely to occur. Conceivable. However, as the read track becomes narrower, the interval between the magnetic domain control films becomes inevitably narrower, and the effect of suppressing Barkhausen noise becomes stronger. Therefore, it can be said that the structure is suitable for a narrow track MR head. FIG. 2 (b)
Although a case for defining a track width reading magnetic domain control film 11, the off-track characteristic a current flows in the MR film 10 under the magnetic domain control layer 1 1 is considered poor compared (a), the Since the magnetic domain control film is adjacent to the read track, Barkhausen noise hardly occurs. From this, the structure of FIG. 2B can be used for an MR head having a wide track width.

A structure to which the basic structure of FIG. 2A is applied will be described below. In this structure, when the electrode film or the magnetic domain control film is processed by ion milling or dry etching, the MR film in the read track portion is damaged, and the characteristics are deteriorated. In order to prevent this, FIG. 3 shows a structure in which a high-resistance non-magnetic thin film which does not impair the magnetic characteristics of the MR film and in which the loss of the sense current is negligible is arranged in the read track portion. In the figure, the same reference numerals as those in FIGS. 2A and 2B denote the same parts.

When the structure shown in FIG. 2A is applied to an MR head having a narrow track, it is necessary to reduce the width of the electrode film in order to reduce the distance between the magnetic domain control films. At this time, FIG. 4 shows a structure in which the area of the surface where the MR film 10 and the electrode film 12 are electrically continuous is increased in order to ensure sufficient electrical contact between the MR film and the electrode film. Since domain control is performed using exchange coupling, the magnetic domain control films cannot be separated from each other by more than the length in which the spin directions are aligned. Therefore, the cross-sectional structure is as shown in FIG. 4A.
The magnetic domain control film and the electrode film on the film surface are, for example, as shown in FIG.
The following arrangements can be adopted. FIG.
In consideration of the fact that the magnetic domain is likely to be generated from the end in the R film, the surface where the MR film and the magnetic domain control film are magnetically continuous at the end is relatively increased to improve the effect of the magnetic domain control. FIG. 3 is a cross-sectional view of a folded structure.

FIGS. 5 and 7 are cross-sectional views of the structures shown in FIGS. 3 and 4 and the structure obtained by combining the structures shown in FIGS. Here, with respect to the arrangement of the magnetic domain control film and the electrode film on the MR film surface, several arrangements can be adopted as shown in the relationship between FIGS. 4A and 4B. These structures do not damage the read track portion of the MR film and hardly generate magnetic domains, so that an MR head for a narrow track having excellent reproduction characteristics can be expected.

Next, a structure to which the basic structure of FIG. 2B is applied will be described. One of the advantages when the read track is defined by the magnetic domain control film is that, by arranging the end portion of the electrode film at an angle with respect to the easy magnetization direction of the MR film as shown in FIG. In some cases, a lateral bias magnetic field can be applied without providing a lateral bias magnetic field application structure. A structure is known in which a read track is defined by an electrode film, and the end of the electrode film is arranged at an angle with respect to the direction of easy magnetization of the MR film. There was a disadvantage that it would shift. This disadvantage is improved in the structure of the present invention in which the read track is defined by the magnetic domain control film. FIG. 9 shows a structure in which a high-resistance non-magnetic thin film is arranged on a read track portion in order to prevent damage to an MR film due to ion milling or dry etching when processing an electrode film or a magnetic domain control film. In this structure, both sides of the read track on the MR film surface are covered with the magnetic domain control film, and there is no damage to the periphery of the read track.

FIG. 2B is a sectional view of a structure in which the area of the surface where the MR film and the magnetic domain control film are magnetically continuous is increased to enhance the magnetic domain control effect. At this time, the distance between the magnetic domain control films is shorter than the length in which the spin directions are aligned by exchange coupling, and the arrangement of the magnetic domain control films and the electrode films on the MR film surface has some arrangements as shown in FIG. 10B. Can be taken. FIG. 12 is a cross-sectional view of a structure in which the surface where the MR film and the magnetic domain control film are magnetically continuous is relatively increased in the periphery of the MR film where magnetic domains are likely to be generated.
This structure has a high Barkhausen noise suppressing effect.

FIGS. 11 and 13 are cross-sectional views of the structures shown in FIGS. 9 and 10, and the structure obtained by combining the structures shown in FIGS. 9 and 12, respectively. Here, with respect to the arrangement of the magnetic domain control film and the electrode film on the MR film surface, several arrangements can be adopted as described above. These have a structure that does not damage the read track portion and the end portion of the MR film and hardly generate magnetic domains, so that excellent reproduction characteristics can be expected.

[0028]

The present invention will be described below in detail with reference to examples.

FIG. 1 is a perspective view of an MR head according to an embodiment of the present invention. A permalloy is formed by sputtering as a lower shield film 17 on a nonmagnetic substrate 18 on which a thin insulating layer (not shown) of alumina or the like is formed and precision polished, and patterned into a predetermined shape by ion milling. And an alumina insulating film 16 was formed thereon. Ni, which is a soft magnetic thin film 15 for applying a lateral bias magnetic field,
-A Fe-Nb alloy and Ta as the nonmagnetic conductive thin film 14 and Permalloy as the MR film 10 were formed by sputtering, and a predetermined pattern was formed by ion milling. After forming alumina as the high-resistance nonmagnetic thin film 13 and removing it by ion milling while leaving a read track portion, NiO as the high-resistance magnetic domain control film 11 and Au as the electrode film 12 were produced by a lift-off method. At this time, the read track is defined by the electrode film, and a path through which the sense current flows is secured in a portion near the read track. The area of the surface where the MR film and the electrode film are electrically continuous is large.
The arrangement is such that the area of the surface where the MR film and the domain control film are magnetically continuous is large. An alumina insulating film 19 was formed thereon and patterned. After forming a resist as the protective film 20, an upper shield film 21 made of permalloy was formed and patterned. Photolithography technology was used for patterning the alumina insulating film 19 and the upper shield film 21. In order to magnetize NiO as the magnetic domain control film 11, heat treatment was performed at 275 ° C. for 30 minutes while applying a DC magnetic field of 3 kOe in the read track width direction, and then processed into an MR head.

In this embodiment, the upper shield film 21 and the lower shield film 17 are made of permalloy.
-Al-Si alloys can also be used. If high resolution is not required, they need not be provided.

As the material of each film, in addition to the above-mentioned materials,
The soft magnetic thin film 15 may be made of a Ni—Fe alloy such as Rh and Ru.
Alloy or Co-Zr-Mo amorphous alloy, Nb, Ti or Mo as the non-magnetic conductive thin film 14,
As the MR film, a Ni—Co alloy, a Fe—Co alloy, or an Fe—Ni—Co alloy is used.
1 is an oxide permanent magnet such as Ba ferrite or Sr ferrite or a NiO—CoO-based antiferromagnetic material;
Ta, NiCr, or the like can be used as the high-resistance nonmagnetic thin film 13, and Cu, W, or the like can be used as the electrode film 12.

With respect to the MR head manufactured as described above, the coercive force is 1600 Oe and the thickness of the magnetic material is t _mag = 20 n.
m, the product of residual magnetic flux density Br and magnetic film thickness Br · t _mag =
A recording pattern recorded at 5 kFCI on a 180 G.mu.m Co-Ta-Cr sputter medium using an induction type thin film magnetic head was reproduced at a flying height of 0.15 .mu.m and a sense current of 12 mA, and the reproduced output was evaluated. . For comparison, an MR film, a non-magnetic conductive thin film, a soft magnetic thin film, and a protective film are sequentially formed on the magnetic domain control film which has been removed by ion milling only in the read track portion, and after patterning, an electrode film is formed. The same evaluation was performed for the MR head having the above structure. As a result, in the present embodiment, Barkhausen noise was not observed, and the reproduction output was 350 μV, whereas in the comparative example, Barkhausen noise was observed and the reproduction output was 230 V.
It was as small as μV.

[0033]

According to the present invention, even when a magnetic domain control film having a high resistance is used, an MR film can be formed on a flat base having no step, and an arrangement without a magnetic domain control film in a read track portion can be obtained. Therefore, an MR head having a large reproduction output without Barkhausen noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a magnetic head according to the present invention.

FIG. 2 is a sectional view showing the basic structure of the magnetic head of the present invention.

FIG. 3 shows a first application example of a basic structure in which a read track is defined by an electrode film.

FIG. 4 shows a second applied example of the basic structure in which a read track is defined by an electrode film.

FIG. 5 is a third application example of a basic structure in which a read track is defined by an electrode film.

FIG. 6 is a fourth applied example of the basic structure in which a read track is defined by an electrode film.

FIG. 7 shows a fifth application example of the basic structure in which a read track is defined by an electrode film.

FIG. 8 shows a first application example of a basic structure in which a read track is defined by a magnetic domain control film.

FIG. 9 shows a second application example of the basic structure in which a read track is defined by a magnetic domain control film.

FIG. 10 shows a third application example of the basic structure in which a read track is defined by a magnetic domain control film.

FIG. 11 shows a fourth application example of the basic structure in which a read track is defined by a magnetic domain control film.

FIG. 12 shows a fifth application example of the basic structure in which a read track is defined by a magnetic domain control film.

FIG. 13 shows a sixth application example of the basic structure in which a read track is defined by a magnetic domain control film.

[Explanation of symbols]

10 ... MR film, 11 ... High resistance magnetic domain control film, 12 ... Electrode film, 13 ... High resistance non-magnetic thin film, 14 ... Non-magnetic conductive thin film, 15 ... Soft magnetic thin film, 16, 19 ... Alumina insulating film,
17: lower shield film, 18: non-magnetic substrate, 20: resist protective film, 21: upper shield film, 22: protective film.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Moriaki Fuyama 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Takao Imagawa 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi, Ltd. Hitachi Research Laboratory (56) References JP-A-4-149812 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/39

Claims (3)

(57) [Claims] And 1. A magnetoresistive film, and the magnetic domain control film for controlling the <br/> magnetic District of the magnetoresistive film, and a pair of electrode films for supplying current to the magnetoresistive film, said magnetoresistive the magnetoresistance effect type head and a means for applying a bias magnetic field to effect film, said electrode film and said magnetic and said magnetic domain control film
On both sides except the reading track of the air resistance effect film, and
Wherein they are arranged alternately in contact with the magnetoresistive film, the magnetoresistive effect film and the electrode film and have that surface contact is more than two及
Fine the magnetoresistive film and the magnetoresistive head, characterized in that the magnetic domain control layer and optionally that surface contact is there more than two. 2. The method according to claim 1, wherein the magnetoresistive effect film and the magnetic domain control film are
The area of the surface in contact with the magnetoresistive film and the electrode
Characterized by being larger than the area of the surface in contact with the membrane
The magnetoresistive head according to claim 1. 3. A magnetic domain control film and an electrode on a magnetoresistive film.
Disk with a magnetoresistive magnetic head
In the magnetic head device, the magnetoresistive head is a magnetic head.
A resistance effect film, and a magnetic field controlling a magnetic domain of the magnetoresistive effect film.
A domain control film and a pair for supplying a current to the magnetoresistive film.
A bias magnetic field to the electrode film and the magnetoresistive film.
A magnetoresistive head having means for performing
The magnetic domain control film and the electrode film read the magnetoresistive effect film.
On both sides except the take-up track, and the magnetoresistance effect
The magnetoresistance effect film and the film are alternately arranged in contact with the film.
Three or more surfaces in contact with the electrode film and the magnetoresistance effect
Three or more surfaces where the fruit film and the magnetic domain control film are in contact
A magnetic disk drive.