JPH0883408A - Thin film magnetic head - Google Patents

Abstract

PURPOSE: To improve the line recording density by making it possible to change gap length at the time of recording and gap length at the time of reproducing. CONSTITUTION: This thin film magnetic head is composed of an opened loop magnetic circuit on which magnetic cores by are formed by a lower magnetic pole 1 and an upper magnetic core 2 and which has a magnetic cap 3 by nonmagnetic films on the side of the surface to face recording media and a coil 4 which consists of conductors intersecting with the magnetic circuit by passing the spacing between the upper magnetic pole 2 and the lower magnetic pole 1. At least one of the magnetic poles are formed by a laminated structrure consisting of a high-permeability magnetic film 5, a high-saturation magnetic flux density magnetic film 6 and a low-saturation magnetic flux density magnetic film 7 in this order. The low-saturation magnetic flux density magnetic film 7 is arranged on the magnetic gap 3 side. The low-saturation magnetic flux density magnetic film 7 is satd. by the magnetic field generated at the time of recording and the magnetic permeability thereof exhibits a value similar to the magnetic permeability of air. A reproducing gap length is determined by the magnetic gap 3 consisting of the nonmagnetic films at the time of reproducing and the excellent reproducing characteristics with less gap loss by the narrow gap are exhibited. The recording density is, therefore, improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic pole structure of a thin film magnetic head mounted in a magnetic storage device.

[0002]

2. Description of the Related Art In order to improve the recording density, it is necessary to increase the coercive force of the magnetic recording medium and narrow the gap of the magnetic head in accordance with the recording wavelength. However, in order to magnetize the high coercive force medium, it is necessary to generate a strong magnetic field,
In a narrow gap head, the magnetic saturation of the magnetic film in contact with the gap determines the upper limit of the magnetic field that can be generated, so that sufficient recording cannot be performed.

Therefore, there is a thin film magnetic head in which a magnetic film having a high saturation magnetic flux density is provided on the upper side of the lower magnetic film and the lower side of the upper magnetic film, as described in JP-A-57-24015. An example of this head structure is shown in FIGS. A high saturation magnetic flux density material for suppressing head saturation is arranged in the gap.

[0004]

In the above prior art, a magnetic film having a high saturation magnetic flux density is used above the lower magnetic film and below the upper magnetic film as a means for improving the recording density. It is difficult to magnetize a high coercive force medium of 1800 oe or more, which corresponds to the further improvement of the recording density.

That is, a narrow gap of about 0.3 μm is required for reproduction and a wide cap of about 0.4 μm is required for recording, and it is extremely difficult to satisfy both of these requirements with a head that also serves for recording and reproduction. It has become difficult.

Further, since the material having a high saturation magnetic flux density has a low magnetic permeability, the magnetic gap at the tip of the gap appears to be widened, and the reproduction efficiency is lowered due to the increase in the magnetic resistance due to the low magnetic permeability, so that the reproduction output is low. There was a problem of becoming.

It is an object of the present invention to provide a magnetic head which is capable of easily magnetizing a high coercive force medium and having excellent reproducing characteristics, with the object of improving the recording density.

[0008]

According to the present invention, as shown in FIG. 1, a magnetic core is formed by a lower magnetic pole 1 and an upper magnetic pole 2, and a magnetic gap 3 is formed by a non-magnetic film on the side facing a recording medium. In a thin-film magnetic head composed of an open loop magnetic circuit having a coil, and a coil 4 made of a conductor passing through the upper magnetic pole and the lower magnetic pole and interlinking the magnetic circuit, at least one magnetic pole is The high permeability magnetic film 5, the high saturation magnetic flux density magnetic film 6 and the low saturation magnetic flux density magnetic film 7 are formed in this order in a laminated structure, and the low saturation magnetic flux density magnetic film side is arranged on the magnetic gap side.

[0009]

In the thin film magnetic head, at least one of the magnetic poles is formed by laminating the high permeability magnetic film 5, the high saturation magnetic flux density magnetic film 6 and the low saturation magnetic flux density magnetic film 7 in this order. The film is arranged on the magnetic gap side. The magnetic field generated at the time of recording saturates the low saturation magnetic flux density magnetism, and its magnetic permeability has a value similar to that of air. That is, the recording gap length is effectively expanded and a strong magnetic field can be generated. This effective recording gap length is a value obtained by adding the magnetic gap 3 made of a non-magnetic film and the low saturation magnetic flux density magnetic film 7. Further, since the high saturation magnetic flux density magnetic film 6 does not reach saturation, a strong and steep magnetic field distribution can be obtained.

Further, during reproduction, the reproduction gap length is determined by the magnetic gap 3 formed by the non-magnetic film and exhibits excellent reproduction characteristics with a small gap loss due to the narrow gap. Therefore, the recording density can be improved.

Further, by making the low saturation magnetic flux density film have a high magnetic permeability, it is possible to prevent the reproduction efficiency from being lowered because the high saturation magnetic flux density magnetic film has a low magnetic permeability.

[0012]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a thin film magnetic head according to the present invention.

As shown in FIG. 1, the thin film magnetic head has a magnetic core formed of a lower magnetic pole 1 and an upper magnetic pole 2, and has an open loop shape having a magnetic gap 3 made of a non-magnetic film on the side facing the recording medium. A magnetic circuit and a coil 4 made of a conductor passing through between the upper magnetic pole and the lower magnetic pole and interlinking the magnetic circuit. The upper magnetic pole has a high permeability magnetic film 5 and a high saturation magnetic flux density magnetic film. 6 and the low saturation magnetic flux density magnetic film 7 are formed in this order by a laminated structure, and the low saturation magnetic flux density magnetic film side is arranged on the magnetic gap side.

FIG. 4 shows the calculation results of the magnetic field distribution in the magnetic saturation region and the tip of the head of the first embodiment. The high magnetic permeability magnetic film 5 of the upper magnetic pole is NiFe (Bs = 1T, magnetic permeability :: 1000, film thickness 3 μm) and the high saturation magnetic flux density magnetic film 6 is CoFeNi (Bs = 1.7T, magnetic permeability: 500,
The film thickness 0.7 μm) and the low saturation magnetic flux density magnetic film 7) are NiF.
e (Bs = 1T, magnetic permeability: 1000, film thickness 0.1 μm)
A laminated structure was formed in order.

The low saturation magnetic flux density magnetic film 7 is completely saturated. Further, the high saturation magnetic flux density magnetic film 6 is not saturated. FIG. 5 compares the calculation results of the magnetic field distribution of the conventional head of the type of FIG. 3 and the head of the present invention shown in FIG. Although the gap length of the head of the present invention is 0.3 μm, it shows a magnetic field distribution almost equal to that of the conventional head having a gap length of 0.4 μm.

Thus, the high saturation magnetic flux density magnetic film and the low saturation magnetic flux density magnetic film are effective even if the same magnetic film is used.

FIG. 6 compares the writing ability of the conventional head with that of the present invention by an experiment.

The shapes of the compared products are the same as the above calculation.

In the conventional head, when the gap length is set to 0.3 μm, compared with the case where the gap length is 0.4 μm, the over-width is over.
The write performance is reduced by about 3 dB. The head of the present invention has a gap length of 0.3 μm and exhibits the same performance as the conventional head gap length of 0.4 μm.

Further, the examination result of reproduction will be shown.

FIG. 7 shows the definition of a solitary wave reproduction waveform. The half width of the waveform is PW50 and the amplitude is V0.

FIG. 8 shows the calculation result of the relationship between the reproduction gap length and the half width. In the case of self-recording / reproducing, it can be seen that when the gap length is narrowed, the half width becomes narrower, which is suitable for high density recording. Also, when the recording gap length is fixed at 0.4 μm, the values are almost the same, which indicates that the reproducing characteristic is determined by the reproducing gap length.

9 and 10 show the experimental results of the relationship between the gap length, the half width and the output.

The head of the present invention has a narrower half-width and a larger output than the conventional head having a gap length of 0.3 μm, and has a low saturation magnetic flux density and a high magnetic permeability. That is, the head of the present invention operates as a head of 0.4 μm at the time of recording and 0.3 μm at the time of reproducing, and because the magnetic film in contact with the gap film has a high magnetic permeability, the waveform is steeper and has a higher output than the conventional head. You can see that you can get

Further, since the crystal structures of the respective magnetic films are similar, CoFeNi on NiFe having a good underlying film quality grows epitaxially, and NiFe on it also grows similarly, so that it has a crystal structure. Moreover, it is also magnetically very stable, and noise such as wiggle or popcorn noise does not occur. In the two-layer structure seen in the conventional example, the underlayer is a high saturation magnetic flux density magnetic film, and generally the magnetic anisotropy is strong, so that the film quality is deteriorated and the reproduction output is decreased. Therefore, this structure is excellent in terms of magnetic recording and crystal structure.

These magnetic films have the same effect by the sputtering method and the plating method. Particularly, when the magnetic film of the conventional head is formed by the plating method, if the low saturation magnetic flux density material is used as the plating underlayer film of the high saturation magnetic flux density material, a great effect can be obtained without making a large change in the process.

11, FIG. 12, FIG. 13, FIG. 13, and FIG.
4, FIG. 15 and FIG. 16 are other embodiments of the present invention.

FIG. 11 shows that the lower core has the same structure as the upper core.
A layer structure was adopted.

In FIG. 12, the lower core is a high saturation magnetic flux density magnetic film 6.

In FIG. 13, the lower core has a two-layer structure of a high magnetic permeability magnetic film 5 and a high saturation magnetic flux density magnetic film 6.

In FIGS. 14, 15 and 16, the length of the high saturation magnetic flux density magnetic film 6 is made equal to the gap depth to facilitate saturation in the gap.

[0032]

According to the present invention, the gap length at the time of recording and the gap length at the time of reproducing can be changed, a magnetic field strength sufficient for recording a high coercive force medium can be obtained, and the linear recording density can be improved. I can. From these facts, by using the magnetic head of the present invention, it is possible to improve the recording density in the high coercive force medium. Further, noise due to the magnetic domain structure can be suppressed, and a highly reliable head can be supplied.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional magnetic head structure.

FIG. 3 is a sectional view showing a conventional magnetic head structure.

FIG. 4 is a magnetic saturation region at the tip of a thin film magnetic head.

FIG. 5 is a magnetic field distribution diagram of the thin film magnetic head.

FIG. 6 is a graph showing the relationship between gap length and overwrite.

FIG. 7 is a waveform diagram illustrating an isolated waveform.

FIG. 8 is a graph showing the relationship between the reproduction gap length and the half-width of the isolated waveform.

FIG. 9 is a graph showing the relationship between the gap length and the half width.

FIG. 10 is a graph showing the relationship between the gap length and the output voltage of an isolated waveform.

FIG. 11 is a sectional view showing another embodiment of the present invention.

FIG. 12 is a sectional view showing another embodiment of the present invention.

FIG. 13 is a sectional view showing another embodiment of the present invention.

FIG. 14 is a sectional view showing another embodiment of the present invention.

FIG. 15 is a sectional view showing another embodiment of the present invention.

FIG. 16 is a sectional view showing another embodiment of the present invention.

[Description of symbols] 1 lower magnetic pole 2 upper magnetic pole 3 magnetic gap 4 coil 5 high permeability magnetic film 6 high saturation magnetic flux density magnetic film 7 low saturation magnetic flux density magnetic film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masayoshi Kagawa 2880 Kokuzu, Odawara, Kanagawa Stock Company Hitachi Storage Systems Division (72) Inventor Makoto Saito 2880, Kozu, Odawara, Kanagawa Hitachi Storage Co., Ltd. System Division

Claims (11)

[Claims] 1. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on a surface facing a recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. And a low saturation magnetic flux density magnetic film side is arranged on the magnetic gap side. 2. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the surface facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. In a thin film magnetic head having a low saturation magnetic flux density magnetic film side disposed on the magnetic gap side, the saturation magnetic flux density of the high magnetic permeability magnetic film is Bs1 and the saturation magnetic flux density of the high saturation magnetic flux density magnetic film is Where Bs2 is the saturation magnetic flux density of the magnetic film and Bs3 is the saturation magnetic flux density of the magnetic film, the following relational expression holds. Bs1 <Bs2, Bs3 <Bs2 3. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the surface facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least the magnetic pole on the side that determines the gap depth is a high permeability magnetic film and a high saturation magnetic flux density magnetic film. A thin film magnetic head characterized in that a low saturation magnetic flux density magnetic film is formed in this order by a laminated structure, and the low saturation magnetic flux density magnetic film side is arranged on the magnetic gap side. 4. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the side facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. And a low saturation magnetic flux density magnetic film made of the same magnetic material. 5. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the side facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. A thin-film magnetic head characterized in that the composition of each magnetic film is based on NiFe. 6. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the side facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. And a high saturation magnetic flux density magnetic film grows on the low saturation magnetic flux density magnetic film according to the crystal of the low saturation magnetic flux density magnetic film. 7. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the side facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. In a thin-film magnetic head formed by a laminated structure of, the low saturation magnetic flux density magnetic film side is disposed on the magnetic gap side, the high magnetic permeability magnetic film has a film thickness t1, and the high saturation magnetic flux density magnetic film has a film thickness t2. The following relational expression holds when the film thickness of the low saturation magnetic flux density magnetic film is t3. t1>t2> t3 8. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the surface facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. In a thin film magnetic head having a low saturation magnetic flux density magnetic film side disposed on the magnetic gap side, the saturation magnetic flux density of the high magnetic permeability magnetic film is Bs1, film thickness t1, high saturation magnetic flux density magnetic film. The following relational expression holds when the saturation magnetic flux density is Bs2, the film thickness is t2, and the saturation magnetic flux density of the magnetic film is Bs3, and the film thickness is t3. Bs * t2> Bs * t3 9. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on the side facing the recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor that passes through the magnetic circuit and crosses the magnetic circuit, at least one magnetic pole has a high permeability magnetic film, a high saturation magnetic flux density magnetic film, and a low saturation magnetic flux density magnetic film. 1. The low saturation magnetic flux density magnetic film side is arranged on the magnetic gap side, the magnetic permeability of the high magnetic permeability magnetic film is 1000 or more, and the saturated magnetic flux density of the high magnetic flux density magnetic film is 1. A thin film magnetic head having a saturated magnetic flux density of 3 T or more and a saturation magnetic flux density of a magnetic film of 1 T or less. 10. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on a surface facing a recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density, a low magnetic permeability magnetic film, and a low saturation magnetic flux. A thin film magnetic head characterized in that a high density magnetic film and a high permeability magnetic film are formed in this order in a laminated structure, and the low saturation magnetic flux density high permeability magnetic film side is arranged on the magnetic gap side. 11. An open-loop magnetic circuit in which a magnetic core is formed by a lower magnetic pole and an upper magnetic pole, and a magnetic gap is formed by a nonmagnetic film on a surface facing a recording medium, and the upper magnetic pole and the lower magnetic pole. In a thin film magnetic head composed of a coil made of a conductor passing through the magnetic circuit and interlinking the magnetic circuit, at least one magnetic pole has a high magnetic permeability magnetic film, a high saturation magnetic flux density, a low magnetic permeability magnetic film, and a low saturation magnetic flux. A high-permeability magnetic film is formed in a laminated structure in this order, and the low saturation magnetic flux density high-permeability magnetic film side is disposed on the magnetic gap side. The saturated magnetic flux density of the low-permeability magnetic film is 1.3 T or more, the magnetic permeability is 1000 or less,
Low saturation magnetic flux density High magnetic permeability A thin film magnetic head having a saturated magnetic flux density of 1 T or less and a magnetic permeability of 1000 or more.