JPH11339227A - Thin-film magnetic head and magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-film magnetic head, capable of absorbing magnetic fields from adjecent tracks and a magnetic field to be generated from a magnetid shield, when the head is made facing a medium in order to enable the information recording and reproducing of high density. SOLUTION: This head has an MR(magnetoresistance effect) element 2 and is made so as to absorb magnetic fields to be generated from adjacent tracks and a magnetic field to be generated with a magnetic shield with auxiliary shields, by arranging the auxiliary shields 7 at leteral sides which are on a flat plane roughly the same as that of a lower part magnetic shield 1. Moreover, it may be similarly constituted so that an upper part magnetic shield instead of the lower part magnetic shield 1 or to constitute both of them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin film magnetic head and a magnetic storage device using the same, and more particularly to a thin film magnetic head for a hard disk drive and a magnetic storage device suitable for high density recording using the same.

[0002]

2. Description of the Related Art FIG. 2 is a partial perspective view of a merged thin-film magnetic head mainly used in a hard disk drive. This thin-film magnetic head includes a write magnetic pole 3 for generating a magnetic field for writing information on a medium, and a magneto-resistance effect element (hereinafter, MR element) having a magneto-resistance effect for reading a magnetic field generated by recorded magnetization. 2) and M
The R element 2 has a lower magnetic shield 1 and an upper magnetic shield 1b for controlling a magnetic field coming from the medium. Note that the giant magnetoresistance effect (GM
R) and tunnel magnetoresistance effect (TMR).

FIG. 3 is a schematic view of the lower magnetic shield 1 and the MR element 2 of the magnetic head shown in FIG. 2 and a portion of an electrode 4 for passing a current through the MR element.
The MR element 2 and the electrode 4 rest on the lower magnetic shield 1. During the manufacturing process of the thin-film magnetic head, a magnetic field may be applied in the specific direction 5 or the opposite direction to control the magnetic characteristics of the MR element 2 and processed.

FIG. 4 shows the lower magnetic shield 1 shown in FIG.
FIG. 3 is a cross-sectional view (although the electrode 4 is omitted) along a direction 5 in which a magnetic field of the element 2 is to be applied. For example, assuming that a magnetic field is applied from right to left in FIG. 4, the lower magnetic shield 1 having soft magnetic properties is saturated with a weak magnetic field due to a small anisotropic magnetic field, generates magnetization at its end, and generates an MR. A reverse magnetic field 6 is applied to the element 2 in a direction opposite to the direction to be applied. Assuming that the amount of magnetization of the lower magnetic shield 1 at this time is M and the width of the lower magnetic shield 1 is W, a reverse magnetic field 6 applied to the MR element 2
Is approximately represented by M / W. Therefore, in order to apply a magnetic field in a desired direction 5, it is necessary to apply a magnetic field larger than the inverse magnetic field 6.

FIG. 5 is a schematic diagram showing a case where the thin-film magnetic head shown in FIG. 3 actually reads a signal recorded on the recording medium 10. The MR element 2 is located right above the self-track 8 on which a signal to be read is written, and reads the magnetic field generated by the signal. A plurality of tracks 9 are adjacent to the own track 8. The track 9 also generates a leakage magnetic flux,
Part of the magnetic field 12 passes through the lower magnetic shield 1 and passes through the electrode 4
Intersect with As a result, the leakage magnetic flux generates an induced voltage at the electrode 4 by electromagnetic induction, and reduces the signal reading accuracy as noise. This is called crosstalk,
For example, Proceedings of the Japan Society of Applied Magnetics, 1991,
It is reported on page 26. In the figure, reference numeral 12 denotes an electrode terminal.

In order to reduce the crosstalk noise, Japanese Patent Application Laid-Open No. Hei 5-325140 discloses a technique in which the width of the upper and lower magnetic shields on the side facing the recording track is smaller than the width on the non-facing side. Is described. Thereby, the width direction of the magnetic flux penetrating the upper and lower magnetic shields from the side facing the recording track is widened, and the magnetic flux density in the induction region surrounded by the MR element and the electrode is reduced,
The occurrence of crosstalk noise can be suppressed.

[0007]

The above-mentioned prior art has a problem that the crosstalk is not sufficiently suppressed and the following problem is encountered. According to experiments, crosstalk from a track at least about 30 μm away from the self track is measured. If the magnetic shield width W is reduced as shown in FIG. 6 so as to reduce the amount of reading from the adjacent track, the reverse magnetic field 6 is substantially inversely proportional to the magnetic shield width W as described above. The applied magnetic field must be increased. For example, when the shield width W is reduced to 1/10 of the conventional width, the magnetic field that must be applied during the process is increased about 10 times.

Further, when the magnetic shield intersects with the electrode, there is a problem that noise is generated by the magnetic field generated by the magnetic shield.

An object of the present invention is to provide a thin film magnetic head capable of suppressing a magnetic field from an adjacent track and suppressing a magnetic field generated by a magnetic shield in order to enable high-density information recording and reproduction. Is to provide. Another object of the present invention is to provide a highly reliable magnetic storage device using such a thin-film magnetic head.

[0010]

In order to achieve the above object, a thin-film magnetic head according to the present invention has a magnetoresistive element, an upper magnetic shield and a lower magnetic shield as a reproducing head, and has an upper magnetic shield and a lower magnetic shield. Substantially flush with at least one of the magnetic shields, and
An auxiliary shield is arranged on the side of the magnetic shield. The auxiliary shield absorbs a magnetic field generated from an adjacent track when the thin-film magnetic head is opposed to the magnetic recording medium, and reduces a magnetic field generated from the magnetic shield. It is intended to be absorbed.

FIG. 1 shows an example of a thin-film magnetic head according to the present invention. FIG. 1 is a cross-sectional view along a direction in which a magnetic field of an MR element and a lower magnetic shield is to be applied. An auxiliary shield 7 is provided next to the lower magnetic shield 1 in order to absorb a reverse magnetic field which becomes strong when the magnetic shield width is reduced. The presence of the auxiliary shield 7 makes it possible to increase the width of the magnetic shield for generating an effective reverse magnetic field 6, that is, the total width of the lower magnetic shield 1 and the auxiliary shield 7, thereby suppressing the applied magnetic field during the process. . In this example, the example of the lower magnetic shield has been described.
Both lower magnetic shields may be as described above.

As described above, crosstalk is detected from a range of about 30 μm on one side. Therefore, the width of the magnetic shield on the air bearing surface side is preferably set to 60 μm or less. It is preferable that the width is equal to or larger than the track width of the magnetic recording medium disposed on the air bearing surface.

Further, the magnetization amount M of the auxiliary shield (= Br ×
T: where Br is the residual magnetic flux density and T is the film thickness) is preferably equal to or more than the magnetization amount M of the magnetic shield. In particular, the magnetization amount M of the auxiliary shield is more preferably about 1 to 5 times the magnetization amount M of the magnetic shield from the viewpoint of ease of manufacture. One of the methods configured in this way is, for example, a method in which the film thickness of the auxiliary shield is larger than the film thickness of the magnetic shield. The auxiliary shield is saturated by an external magnetic field and generates a magnetic field.However, when the magnetization is increased by increasing the film thickness, the magnetic field generated by the auxiliary shield exceeds the magnetic field generated by the magnetic shield and is applied to the MR element. On the other hand, a forward magnetic field can be generated. Another method is to use different materials for the auxiliary shield and the magnetic shield.

As described above, the auxiliary shield is provided on the lateral side of the substantially same plane as the magnetic shield. However, when the thicknesses of both are different, it is sufficient that one of the two surfaces is substantially on the same plane.

According to another aspect of the present invention, there is provided a magnetic storage device comprising: a magnetic recording medium; a driving unit for driving the magnetic recording medium in a recording direction; a magnetic head including a recording unit and a reproducing unit; The magnetic head has means for moving the magnetic head relative to the magnetic recording medium, for example, a guide arm, and recording / reproducing signal processing means for obtaining a recording signal input to the magnetic head and a reproducing signal output from the magnetic head. The thin-film magnetic head described in any of the above is used as the head.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 7 is a plan view of the portion of the lower magnetic shield 1, the MR element 2, and the electrode 4 of the thin-film magnetic head according to one embodiment of the present invention, which is located above the recording medium 10. This figure is a cross-sectional view corresponding to FIG. 5 described above. As shown in the figure, the magnetic shield is divided into a lower magnetic shield 1 and an auxiliary shield 7. The distance between the lower magnetic shield 1 and the auxiliary shield 7 is preferably smaller than the film thickness of the divided magnetic shield and is at least 1/10 of the film thickness. In addition,
The auxiliary shield 7 has the same thickness and the same plane as the lower magnetic shield 1, but when the lower magnetic shield 1 and the auxiliary shield 7 have different thicknesses, the above-mentioned interval is based on the thicker thickness. You only have to decide. Also, the lower magnetic shield 1
Is 60 μm or less, and is equal to or more than the track width of the magnetic recording medium disposed on the air bearing surface.

In manufacturing such a magnetic head, an insulating layer is formed after a magnetic shield is formed by sputtering or plating, and an MR element and an electrode are formed. The structure of this embodiment can be obtained by using a mask conforming to the shapes of the lower magnetic shield 1 and the auxiliary shield in the magnetic shield forming process.

FIG. 8 is a plan view of a portion similar to the above in another embodiment of the present invention. By preventing the auxiliary shield 7 from overlapping the electrode 4 in this plan view, the magnetic flux from the adjacent track 9 reaching the electrode 4 is further suppressed. This structure can also be realized by using a mask conforming to this shape as in the above embodiment.

FIGS. 10 and 11 are plan views of only the lower magnetic shield. Other parts are the same as the structure shown in FIG. 7, and are examples in which only the shape of the lower magnetic shield is changed. FIG. 10 shows a configuration in which the magnetic flux affecting the crosstalk is further moved away from the electrode 4 by enlarging the area of the magnetic shield 1 that enters the electrode side from the air bearing surface side.

FIG. 11 shows an example in which the auxiliary shield 7 and a part of the lower magnetic shield 1 are connected. In realizing the present invention, it is not always necessary to completely separate the auxiliary shield 7 and the lower magnetic shield 1, and the auxiliary shield 7 may be used where there is almost no magnetic flux entering the lower magnetic shield.
And the lower magnetic shield 1 may be connected. With these structures, crosstalk to the electrode 4 is further suppressed,
Further, it has a structure capable of absorbing the magnetic field generated by the lower magnetic shield 1.

Next, an embodiment in which the magnetization amount of the auxiliary shield 7 is larger than the magnetization amount of the lower magnetic shield 1 will be described. This can be done in two ways. One is a method in which the film thickness of the auxiliary shield is made larger than the film thickness of the magnetic shield 1 as shown in FIG. The auxiliary shield is saturated by the external magnetic field and also generates a magnetic field. However, when the amount of magnetization M is increased, as shown in FIG.
b exceeds the magnetic field generated by the lower magnetic shield.
A forward magnetic field can be generated for the R element.

Another method is to use a material different from that of the lower magnetic shield 1 for the auxiliary shield 7. For example, Ni-Fe having a saturation magnetic flux density of 1T is used as the material of the lower magnetic shield, and Co-Nb-Zr having a saturation magnetic flux density of 1.3T is used as the material of the auxiliary shield. Both of them are soft magnetic materials, and when they have the same thickness, the magnetization amount of the auxiliary shield can exceed the magnetization amount of the magnetic shield.

The auxiliary shield 7 may be made of a hard magnetic material or a combination of a soft magnetic material and an antiferromagnetic material. In this method, since a magnetic field in a fixed direction can be applied to the lower magnetic shield 1, it can also be used to control the magnetic domain state of the lower magnetic shield 1. Here, when a hard magnetic material is used for the auxiliary shield 7, it is conceivable that when the hard magnetic material comes out on the air bearing surface, the medium magnetization may be erased. Processing such as engraving or cutting may be necessary.

In the above two examples in which the magnetization of the auxiliary shield 7 is larger than the magnetization of the lower magnetic shield 1, the lower magnetic shield 1 and the auxiliary shield 7 cannot be formed in the same process. Manufactured in process.

In the above embodiment, only the lower magnetic shield has been described as an example, but the above structure can be applied to only the upper magnetic shield or to both the upper and lower magnetic shields.

FIG. 12 is a partial perspective view of one embodiment of the magnetic storage device of the present invention. This magnetic storage device has a magnetic recording medium 203 that has a low medium noise and is excellent in electromagnetic conversion characteristics with a high coercive force and can record at an extremely high areal recording density.
A spindle motor 202 as a driving unit for driving the recording medium in a recording direction; a thin-film magnetic head 204 of the present invention including a recording unit and a reproducing unit; The thin-film magnetic head 204 includes a guide arm 205 serving as a means for causing the thin-film magnetic head 204 to input a signal, and a recording / reproducing signal processing circuit 201 for reproducing an output signal from the thin-film magnetic head 204. When the thin film magnetic head of the present invention shown in the above-described embodiment was provided in this magnetic storage device and the noise components from adjacent tracks were examined, the total S / N was superior to that of the conventional thin film magnetic head.

It is needless to say that the magnetic storage device may have a configuration in which a plurality of magnetic recording media 203 and a plurality of thin-film magnetic heads 204 are provided in the guide arm 205. The thin-film magnetic head 204 has an anisotropic magnetoresistance effect (A
The present invention can be applied not only to an MR head using MR) but also to a spin-valve MR head using a giant magnetoresistance effect (GMR).

[0028]

According to the present invention, crosstalk from an adjacent track can be suppressed without deteriorating the characteristics of the MR element during the process.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thin-film magnetic head according to an embodiment of the present invention, taken along a direction in which a magnetic field is to be applied to an MR element and a lower magnetic shield.

FIG. 2 is a partial perspective view of a conventional merged magnetic head.

FIG. 3 is a partial schematic view of a conventional merged magnetic head.

FIG. 4 is a cross-sectional view along a direction in which a magnetic field of an MR element and a lower magnetic shield of a conventional magnetic head is to be applied.

FIG. 5 is a plan view of a lower magnetic shield, an MR element, and electrodes of a conventional magnetic head.

FIG. 6 is a graph showing M when the width of the shield of the magnetic head is reduced.
FIG. 4 is a cross-sectional view of the R element and the lower magnetic shield taken along a direction in which a magnetic field is to be applied.

FIG. 7 is a plan view of a lower magnetic shield, an MR element, and electrodes of the thin-film magnetic head according to one embodiment of the present invention.

FIG. 8 is a plan view of a lower magnetic shield, an MR element, and electrodes of a thin-film magnetic head according to another embodiment of the present invention.

FIG. 9 is a sectional view of a thin-film magnetic head according to still another embodiment of the present invention, taken along a direction in which a magnetic field of the MR element and the lower magnetic shield is to be applied.

FIG. 10 is a plan view of a lower magnetic shield of a thin-film magnetic head according to still another embodiment of the present invention.

FIG. 11 is a plan view of a lower magnetic shield of a thin-film magnetic head according to still another embodiment of the present invention.

FIG. 12 is a schematic view of a magnetic storage device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lower magnetic shield 1b ... Upper magnetic shield 2 ... MR element 3 ... Write pole 4 ... Electrode 5 ... Direction 6 ... Reverse magnetic field 6b, 12 ... Magnetic field 7 ... Auxiliary shield 8 ... Self-track 9 ... Track 10 ... Recording medium 11 ... Electrode terminal 201: recording / reproducing signal processing circuit 202: spindle motor 203: magnetic recording medium 204: thin-film magnetic head 205: guide arm

Claims (4)

[Claims] 1. A thin film magnetic head having a magnetoresistive element, an upper magnetic shield and a lower magnetic shield as a reproducing head, wherein the thin magnetic head has at least one of the upper magnetic shield and the lower magnetic shield in the same plane. An auxiliary shield is arranged on the side of the magnetic shield, and the auxiliary shield absorbs a magnetic field generated from an adjacent track and a magnetic field generated from the magnetic shield when the thin-film magnetic head is opposed to a magnetic recording medium. A thin film magnetic head characterized in that: 2. The method according to claim 1, wherein the magnetization of the auxiliary shield is equal to or larger than the magnetization of the magnetic shield, and the material of the auxiliary shield is a hard magnetic material or a combination of a soft magnetic material and an antiferromagnetic material. 2. The thin-film magnetic head according to claim 1, wherein: 3. The thin film according to claim 1, wherein the thickness of the magnetic shield is smaller than the thickness of the auxiliary shield, and the magnetization of the auxiliary shield is equal to or larger than the magnetization of the magnetic shield. Magnetic head. 4. A magnetic recording medium, a drive unit for driving the magnetic recording medium in a recording direction, a magnetic head comprising a recording unit and a reproducing unit, means for moving the magnetic head relative to the magnetic recording medium, 4. A magnetic storage device having a recording / reproducing signal processing unit for obtaining a recording signal input to a magnetic head and a reproducing signal output from the magnetic head, wherein the magnetic head is according to any one of claims 1 to 3. A magnetic storage device comprising a thin film magnetic head.