JPH0652521A - Composite thin film magnetic head - Google Patents

Abstract

PURPOSE:To provide a composite thin film magnetic head which can reduce the distortion of an isolated reproduced waveform. CONSTITUTION:The magnetic head is provided with an MR head section 10 for reproduction and inductive head section 11 for recording formed on the section 10. The gap length between a lower magnetic layer 35 and upper magnetic layer 38 constituting the core of the section 11 is set at <0.77mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inductive head for recording on a magnetic medium such as a magnetic disk and a magnetoresistive head (Magneto R) for reproducing from the magnetic medium.
The present invention relates to a composite type thin film magnetic head which is a combination of an essential head (hereinafter referred to as an MR head).

[0002]

2. Description of the Related Art In recent years, MR heads utilizing the magnetoresistive effect have begun to be put into practical use as thin film magnetic heads for magnetic media such as magnetic disks.

The MR head has the advantage that a large reproduction output can be obtained without depending on the relative speed with respect to the magnetic medium, but since it is exclusively for reproduction, it is combined with a recording head for use as a recording / reproducing head. Must be configured.

FIG. 8 schematically shows a known composite type thin film magnetic head in which an MR head and an inductive head for recording are combined from the bottom side facing the magnetic medium.

In the figure, reference numeral 80 denotes a reproducing MR head portion, and 81 denotes a recording inductive head portion provided behind (upper) the MR head portion 80.

In this specification, "before", "after",
“Lateral” refers to the front and back and the side toward the traveling direction of the magnetic head relative to the magnetic medium (see the arrow in the figure).

The MR head portion 80 has an insulating base film 83, a shield layer 84, a gap insulating film 85, an MR element 86, a lead 87, a gap insulating film 88, and a shield layer 89 on the rear end surface of the slider 82. It is formed by sequentially stacking.

A lower (front) magnetic layer 90 and an upper (rear) magnetic layer 91 are formed on the inductive head portion 81. The distance between the lower magnetic layer 90 and the upper magnetic layer 91, that is, the gap length G ₀ is generally G ₀ ≈0.8 μm.
It is set to a degree. The width of the bottom surface of the lower magnetic layer 90 is set larger than the width of the bottom surface of the upper magnetic layer 91. This is because the bottom surfaces of the lower magnetic layer 90 and the upper magnetic layer 91 are arranged in the width direction due to manufacturing reasons. This is done to prevent the track width from changing due to the deviation and to uniquely determine the track width by the width on the side of the upper magnetic layer 91.

[0009]

According to the analysis of the inventors of the present application, according to the conventional composite type thin film magnetic head of this type, the following distortion (base line
It was found that transition noise = BLT noise) occurred. FIG. 9 is a diagram for explaining this reproduced waveform distortion, and FIG. 10 is an actual reproduced waveform diagram obtained by the conventional composite type thin film magnetic head having the structure shown in FIG.

In FIG. 9, reference numeral 92 is a track formed on the magnetic medium by the recording operation of the inductive head portion 81, 93 is a magnetization reversal position on the track 92, and 94 is a magnetization direction. When the MR head section 80 reproduces this track 92, ideally, a pulse-shaped reproduction waveform 96 that sharply rises from the ground level 95 at the magnetization reversal position 93 should be obtained. However, when recording / reproducing is performed by the conventional composite type thin film magnetic head, the reproduced waveform 97 has base line shifts 97a and 97b, and a step 97c appears in front of the main pulse 97d, resulting in a disturbed waveform. turn into. This disturbance of the reproduced waveform is also found from the actually measured waveform chart of FIG.

Since such a waveform disturbance is superposed on the next main pulse, the pulse amplitude is finally changed and the pulse position is changed, resulting in a deterioration of the error rate.

Therefore, the present invention provides a composite type thin film magnetic head capable of reducing the distortion of an isolated reproduction waveform.

[0013]

According to the present invention, there is provided a composite type thin film magnetic head having a novel construction in which an inductive head portion for recording and an MR head portion for reproducing are combined. In this composite thin film magnetic head, the inductive head portion is formed by laminating on the MR head portion, and the core of the inductive head portion has a lower magnetic layer (front magnetic layer) whose tip faces the magnetic medium to be recorded. ) And an upper magnetic layer (rear magnetic layer). The gap length between the tips of the lower magnetic layer and the upper magnetic layer is set to less than 0.7 μm.

It is preferable that the tips of the lower magnetic layer and the upper magnetic layer have rectangular shapes.

The lateral length (width) of the lower magnetic layer may be greater than or equal to the lateral length (width) of the upper magnetic layer.

[0016]

The gap length between the lower magnetic layer and the upper magnetic layer is set to 0.
By significantly reducing the length to less than 7 μm, the magnetic flux easily passes through the gap portion, and the fringing magnetic field generated on the side of the inductive head portion during recording is reduced. As a result, as will be described later, the waveform distortion of the reproduced waveform (base line transition noise = BLT noise) is significantly reduced.

[0017]

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

FIG. 2 is a perspective view showing a flying type magnetic head unit provided with a composite type thin film magnetic head as one embodiment of the present invention.

As shown in the figure, the flying type magnetic head unit of this embodiment has a slider 20 and two composite type thin film magnetic heads 21 provided on the rear end face thereof and a protective film 2 thereof.
It is mainly composed of 2 and. The slider 20 is formed by sputtering a ceramic structure 23 made of a ceramic material such as Al ₂ O ₃ —TiC and an electrically insulating material such as Al ₂ O ₃ or SiO _{2 on} the rear end surface of the ceramic structure 23. And the ground film 24.

The composite type thin film magnetic head 21 is a thin film element formed on the base film 24, and these heads 21 have four electrodes 25 formed so as to be exposed on the surface of the protective film 22 and four leads 26. Are connected to each other.

The protective film 22 is formed by sputtering Al ₂ O ₃ or SiO ₂ or the like, a composite type thin film magnetic head 2
1, the base film 24, and the leads 26 are formed so as to cover the entire surfaces.

FIG. 3 is a partial cross-sectional view taken along the line AA of FIG. 2 to show the structure of the composite type thin film magnetic head 21 in more detail.

On the base film 24 formed on the rear end face of the above-mentioned ceramic structure 23, Ni-containing permalloy or the like is formed.
A shield layer (lower shield layer) 30 is formed by plating an Fe alloy or the like.

The MR element 31 is formed on the shield layer 30.
Are formed so as to be sandwiched between the gap insulating films 32.
That is, the MR element 31 is formed by sputtering and patterning a Ni—Fe alloy such as permalloy on the lower gap insulating film formed by sputtering Al ₂ O ₃ or the like on the shield layer 30. Leads 26 (FIG. 2) made of Cu or the like are formed on the MR element 31 by plating or the like. In addition, a shunt layer for applying a bias to the MR element, a soft film bias layer, and the like are provided as needed by sputtering or the like. MR element 31, lead 2
6 and the upper gap insulating film is formed on the lower gap insulating film by sputtering Al ₂ O ₃ or the like, whereby the gap insulating film 32 is formed.

A shield layer (upper shield layer) 33 is formed on the gap insulating film 32 by plating a Ni-Fe alloy such as permalloy.

The shield layer 30, the MR element 31, the leads 26, the gap insulating film 32, and the shield layer 33 constitute a reproducing MR head portion. Shield layer 33
An insulating film 34 is formed on the upper surface by sputtering Al ₂ O ₃ or the like.

On the insulating film 34, Ni-such as Permalloy is formed.
A lower magnetic layer (front magnetic layer) 35 is formed by plating an Fe alloy, and Al ₂ O ₃ or S is formed on the lower magnetic layer 35.
A coil conductor 37 made of Cu, Au, or the like is provided so as to be sandwiched by an insulating film 36 of iO ₂ or the like, and a Ni—Fe alloy such as permalloy is plated on the coil conductor 37 to form an upper magnetic layer (rear magnetic layer). 38 is formed.

The lower magnetic layer 35 and the upper magnetic layer 38 are coupled to each other at a portion 38a on the side opposite to the surface 39 facing the magnetic medium, thereby forming the core of the inductive head portion for recording. . The coil conductor 37 is formed so as to be spirally wound around the coupling portion 38a of the lower magnetic layer 35 and the upper magnetic layer 38.

The protective film 22 described above is formed on the upper magnetic layer 38.

It is obvious that the lower magnetic layer 35 may be configured so that it also serves as the shield layer 33. In this case, as a matter of course, the insulating film 34
Is omitted.

FIG. 1 shows the composite type thin film magnetic head 21 according to this embodiment on the bottom surface side (surface 39 in FIG. 3) facing the magnetic medium.
Side).

In the figure, reference numeral 10 is a reproducing MR head portion, and 11 is a recording inductive head portion provided behind the MR head portion 10.

As described above, the MR head portion 10 includes the ceramic structure 23, the base film 24, the lower shield layer 30,
Lower gap insulating film 32a, MR element 31, lead 2
6, the upper gap insulating film 32b, and the upper shield layer 3
3 are sequentially laminated and formed, and the inductive head unit 11 has a lower magnetic layer 35 and an upper magnetic layer 38.

In this embodiment, these lower magnetic layer 3
5 and the bottom surfaces of the upper magnetic layer 38 facing the magnetic medium are both rectangular, and the lateral length (width) of the lower magnetic layer 35 is larger than the lateral length (width) of the upper magnetic layer 38. It is set. Moreover, the distance between the lower magnetic layer 35 and the upper magnetic layer 38, that is, the gap length G ₁ is G ₁ <0.7 μ.
m, preferably G ₁ <0.5 μm, which is a fairly small value.

As described above, by greatly reducing the gap length between the lower magnetic layer 35 and the upper magnetic layer 38,
The fringing magnetic field generated during recording can be greatly reduced.

The present inventors have found that the waveform distortion (base line transition noise = BLT noise) is significantly reduced by reducing the fringing magnetic field. This point will be described in detail below.

FIG. 4 is a diagram for explaining the magnetic field generated by the conventional inductive head and the magnetic poles recorded on the magnetic medium by the magnetic field. FIG. 5 shows that the inductive head further travels relatively and the recording current is increased. It is a figure explaining the magnetic field which this head produces | generates when it inverts, the magnetic pole recorded on a magnetic medium by this, and the reproduction | regeneration waveform when this track is read by the MR head.

As is clear from FIG. 4, in the conventional inductive head, the gap 40 is formed during recording.
In addition to the original magnetic field 41 generated in the above step, a large amount of magnetic field (fringing magnetic field) 42 is generated from the side portions on both sides of the upper magnetic layer 91. By this magnetic field 42, the track 4 on the magnetic medium is
The outer portions of both edges of 3 are magnetized obliquely in the direction shown, forming track side poles 44 of the same polarity on both sides of the track.

It is assumed that the inductive head further travels relatively and the recording current is reversed at the position shown in FIG. As a result, the magnetization direction is reversed, and the vicinity of the position of the front surface 91a of the upper magnetic layer 91 at that time becomes the magnetization reversal position (bit position) 45 on the track 43, and the original magnetic pole 46 is formed on this track 43. At this time, at the same time, the strong fringing magnetic fields 47 toward both sides of the upper magnetic layer 91 cause the outer portions of both edges of the track 43 to be obliquely magnetized in the direction opposite to the front direction, which is opposite to that of the track / side magnetic pole 44. A polar track side pole 48 is formed. In the figure, reference numeral 50 denotes an inversion region of the track-side magnetic pole, and the length of the inversion region 50 in the track direction is substantially equal to the length of the upper magnetic layer 91 in the front-rear direction (track length).

When the track 43 thus recorded is read by the MR head, its reproduction waveform 49
, The base line shifts 49a and 49b occur under the influence of the track side magnetic pole 44 and its inversion track side magnetic pole 48, and the step 49c increases the length of the inversion region 50 to the main pulse 49d at the magnetization inversion position 45. This is caused by an amount corresponding to the length, and the waveform is disturbed (baseline transition noise = BL
(T noise) occurs.

It should be noted that such a disturbance in the reproduced waveform is peculiar when a recording inductive head and a reproducing MR head are used in combination. That is, what is recorded by the inductive head is M which is sensitive to the magnetic potential.
It occurs only when read with the R head,
Even if this is read by an inductive head that is sensitive to the magnetic differentiation, this kind of disturbance in the reproduced waveform hardly appears.

On the other hand, with the configuration according to the present embodiment, the generation of fringing magnetic field is significantly reduced, and the reproduced waveform is disturbed (base line transition noise =
BLT noise) can be prevented, and as a result, the peak shift of the reproduced waveform can be reduced and the error rate can be improved. This point will be described in detail below.

FIG. 6 is a diagram for explaining the magnetic field generated by the inductive head of this embodiment and the magnetic poles recorded on the magnetic medium by the magnetic field. FIG. 7 shows the inductive head traveling further relative to recording. FIG. 3 is a diagram for explaining a magnetic field generated by this head when a current is reversed, a magnetic pole recorded on a magnetic medium by this head, and a reproduction waveform when this track is read by an MR head.

In this embodiment, the gap length between the lower magnetic layer 35 and the upper magnetic layer 38 is set so that G ₁ is G ₁ <0.5 μm, which is a very small value. For this reason, the magnetic resistance in the gap 60 becomes relatively smaller than the magnetic resistance of the fringing portion passing through the side of the upper magnetic layer 38, and the magnetic flux easily passes through the gap 60. Therefore, as shown in FIG. 6, the magnetic field (fringing magnetic field) 62 from the side of the upper magnetic layer 38 to the rear end of the lower magnetic layer 35 is relatively relative to the original magnetic field 61 generated in the gap 60. The magnetic field 62 drastically reduces the track formed on the outer side of the edge of the track 63 on the magnetic medium.
The side pole 64 becomes very weak.

It is assumed that the inductive head further travels relatively and the recording current is reversed at the position shown in FIG. As a result, the magnetization direction is reversed, and the vicinity of the position of the front surface 38a of the upper magnetic layer 38 at that time becomes the magnetization reversal position (bit position) 65 on the track 63, and the original magnetic pole 66 is formed on this track 63, and at the same time the lower magnetic A fringing magnetic field 67 is generated from the rear end of the layer 35 to the side of the upper magnetic layer 38, and this fringing magnetic field 67 is also considerably reduced from the original magnetic flux on the track 63 for the same reason as described above. It will be what you did. Therefore, the reverse polarity track-side magnetic poles 68 formed on the outer side of the edge of the track 63 are also very weak. In other words, truck 6
The magnetic pole 66 on 3 is much stronger than the track side magnetic pole 68. In the figure, reference numeral 70 denotes an inversion region of the track / side magnetic pole.
The length in the track direction of 0 is almost equal to the length in the front-rear direction (track direction length) of the lower magnetic layer 38.

When the track 63 thus recorded is read by the MR head, its reproduced waveform 69
, The track side magnetic poles 64 and 68 formed on both sides of the track are very weak, so that the baseline shift hardly occurs as shown in the portions 69a and 69b. Further, since the reverse polarity track-side magnetic pole 68 in the inversion region is also small, the level of the step 69c generated prior to the main pulse 69d becomes small. As a result, the distortion of the isolated reproduction waveform (base line transition noise = BLT noise) can be significantly reduced.

In the embodiments described above, the lengths of the bottom magnetic layer and the bottom magnetic layer facing the magnetic medium in the track width direction are set to be longer in the lower magnetic layer than in the upper magnetic layer. However, in the present invention, this is not an essential requirement, and both may be approximately equal, and the upper magnetic layer may be longer.

The bottom shapes of the lower magnetic layer and the upper magnetic layer do not necessarily have to be rectangular, but may be any other shape.

In the above-mentioned embodiments, the shape and pattern of the bottom surface of the lower magnetic layer and / or the upper magnetic layer facing the magnetic medium are described, but in the present invention, the shape of the lower magnetic layer and / or the upper magnetic layer. It suffices that the pattern of at least the tip facing the magnetic medium is the above-described pattern. Therefore, the cross section of the above-described pattern may be formed over the entire length of the magnetic layer, or the pattern from the bottom facing the magnetic medium to a predetermined position may be used. The cross section of the pattern as described above may be used.

The present invention is not limited to the above-mentioned embodiments, but may have any structure as long as the gap length of the tips of the lower magnetic layer and the upper magnetic layer facing the magnetic medium is less than 0.7 μm. It may be.

Although the magnetic head has been described above, if the magnetic medium is constructed so as not to be magnetized in the direction orthogonal to the track direction (orientated in the track direction), generation of the fringing magnetic field itself can be significantly suppressed. .

[0052]

As described in detail above, according to the present invention, the gap length between the tips of the lower magnetic layer and the upper magnetic layer forming the core of the inductive head portion is set to less than 0.7 μm. The fringing magnetic field generated at the time of recording is relatively reduced with respect to the original magnetic field on the track. As a result, the waveform distortion (base
The line transition noise = BLT noise) is significantly reduced, the peak shift of the reproduced waveform can be reduced, and the error rate can be improved.

[Brief description of drawings]

FIG. 1 is a bottom view schematically showing a composite type thin film magnetic head in the embodiment of FIG. 2 from the bottom side facing a magnetic medium.

FIG. 2 is a perspective view showing a flying type magnetic head unit including a composite type thin film magnetic head as one embodiment of the present invention.

FIG. 3 is a partial cross-sectional view taken along the line AA of FIG.

FIG. 4 is a diagram illustrating a magnetic field generated by a conventional inductive head and magnetic poles recorded on a magnetic medium by the magnetic field.

5 is a magnetic field generated by the inductive head of FIG. 4 when the recording current is further reversed and the recording current is reversed, the magnetic pole recorded on the magnetic medium by the head and the track are read by the MR head. It is a figure explaining the reproduction | regeneration waveform in the case.

FIG. 6 is a diagram illustrating a magnetic field generated by the inductive head and the magnetic pole recorded on the magnetic medium by the magnetic field in the embodiment of FIG.

FIG. 7 is a diagram showing a magnetic field generated by the inductive head of FIG. 6 when the recording current is further driven and the recording current is reversed, the magnetic pole recorded on the magnetic medium by the magnetic field, and the track are read by the MR head. It is a figure explaining the reproduction | regeneration waveform in the case.

FIG. 8 is a bottom view schematically showing a conventional composite type thin film magnetic head from the bottom side facing a magnetic medium.

FIG. 9 is a diagram for explaining reproduction waveform distortion by a conventional composite type thin film magnetic head.

FIG. 10 is an actual reproduction waveform diagram by a conventional composite type thin film magnetic head.

[Explanation of symbols]

 10 MR Head Part 11 Inductive Head Part 23 Ceramic Structure 24 Underlayer Film 26 Lead 30 Lower Shield Layer 33 Upper Shield Layer 31 MR Element 32a Lower Gap Insulation Film 32b Upper Gap Insulation Film 35 Lower Magnetic Layer 38 Upper Magnetic Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazumasa Fukuda 1-13-1 Nihonbashi, Chuo-ku, Tokyo Tea Decay Co., Ltd. (72) Inventor Noboru Yamanaka 1-13-1 Nihonbashi, Chuo-ku, Tokyo DC Inc.

Claims (3)

[Claims] 1. A magnetoresistive head portion for reproduction and an inductive head portion for recording formed by laminating on the magnetoresistive head portion, wherein a core of the inductive head portion is to be recorded. What is claimed is: 1. A composite thin-film magnetic head comprising a lower magnetic layer and an upper magnetic layer whose tips face a magnetic medium, wherein a gap length between the tips of the lower magnetic layer and the upper magnetic layer is less than 0.7 μm. A composite type thin film magnetic head characterized by being set. 2. The composite thin film magnetic head according to claim 1, wherein the tips of the lower magnetic layer and the upper magnetic layer have a rectangular shape. 3. The composite thin film magnetic head according to claim 1, wherein the lateral length of the lower magnetic layer is equal to or greater than the lateral length of the upper magnetic layer.