JPH02105309A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To record the short wavelength with high density by using a laminated matter of a metallic magnetic film of high magnetic permeability and an insulated film to form the greater part of a magnetic core and preparing a metallic magnetic film having saturated magnetic flux density lower than the magnetic core at the leading edge of a gap. CONSTITUTION:A laminated magnetic matter 1 of high permeability is used to form the greater part of a magnetic core. At the same time, a magnetic film 2 having the low saturated magnetic flux density is formed at the leading edge part of a gap 5. A thin film magnetic head of such a constitution has its magnetic core which is chiefly made of a laminated matter 4 containing a metallic magnetic film 1 having the high permeability and an insulated film 3. As a result, the high core efficiency is secured over a wide range of several tens of MHz. Furthermore a wide, intensive and deep magnetic field having the effectively large gap length is generated at the leading edge side of the gap 5 with saturation in a recording state owing to the film 2 prepared at the leading edge side of the gap 5. Then the leading edge side is not saturated either in a reproducing state owing to the low magnetic flux density flowing to the head. Thus the function of a narrow gap is secured and the highly effective reproduction is attained even with the short bit length.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head used for high density, high frequency recording in digital VTRs and large capacity FDDs.

[Prior art] In recent years, C0Zr-N has been used as a high-density, wide-band recording head.
Utilizing the high saturation magnetic flux density of alloy magnetic materials such as amorphous and sendust, we alternately stack films of alloy magnetic material and insulator films such as SiO□ to counteract the eddy current loss that is their drawback. However, a structure (thin film magnetic head) in which this is sandwiched between nonmagnetic substrates has been proposed. For example, the literature [IEICE Study Group Report MR86-28~31 N986) J
Figure 8 shows the head proposed in . In the figure (
4) is a laminate of an alloy magnetic film and an insulating film, (10) is a winding window, (5) is an operating gap, (22) is a low melting point glass, (23) is a crystallized glass layer, (24) is a non-magnetic substrate.

The thin-film magnetic head configured as described above has a multilayer structure (4
) is the track width, so it is easy to control the track width, and unlike ferrite heads and MIG heads, the track width is not controlled by machining, so the track width is extremely narrow, less than 10 μm. It can be easily formed. In addition, since the direction of film formation almost coincides with the track width direction, several layers can be stacked alternately with insulating layers at the optimum film thickness for the metal magnetic film used, so eddy currents can be sufficiently suppressed over a wide band. It can be used as a head for. Furthermore, since the magnetic material that forms the magnetic path is only as thick as the track width over the entire core, the herad inductance per number of coil turns is considerably smaller than in ferrite heads and MIG heads, where the entire core is almost entirely magnetic.
This is quite advantageous in terms of electromagnetic conversion characteristics.

[Problems to be Solved by the Invention] As described above, the thin film magnetic head has excellent characteristics as a high frequency and wide band head, but the metal magnetic film used is amorphous such as Co-Zr-Nb, etc. from the viewpoint of reproduction efficiency.
Alloy magnetic materials such as sendust and permalloy must be made of high magnetic permeability material, with a saturation magnetic flux density of 70
It is about 00 to 10,000 Gauss. For this reason,
If the shortest bit length is 0.3 μm or less, the gap length during playback will be 0.2 μm or less due to gap loss, and recording will be insufficient when recording on metal tape, which is a medium for high recording density. . Moreover, the override characteristics are also deteriorated for this reason.

This invention was made to solve the above-mentioned problems, and has a high frequency, a wide band, and a minimum bit length of 0.
The object is to obtain a magnetic head capable of ultra-high density recording of 3 μm or less.

[Means for Solving the Problems] A thin-film magnetic head according to the present invention has a magnetic core mostly composed of a laminated magnetic material with high magnetic permeability, and a magnetic film having a low saturation magnetic flux density at the leading edge of the gap. It is arranged.

[Effect]

In the thin film magnetic head according to the present invention, most of the magnetic core is composed of a laminate of a metal magnetic film having high magnetic permeability and an insulating film, so that high core efficiency can be ensured over a wide band of several tens of MHz. In addition, since a magnetic film with low saturation magnetic flux density is placed on the leading edge side of the gap, during recording, the leading edge side saturates, effectively widening the gap length, and generating a strong and deep magnetic field. Since the inflowing magnetic flux density is small, the leading edge side is not saturated and operates as a narrow gap, allowing efficient reproduction even with short bit lengths.

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a magnetic head according to an embodiment, and FIG. 2 is an enlarged view of its sliding surface. In Figures 1 and 2, (1) is a high permeability metal magnetic film such as sendust or Co-based amorphous, (2) is a low saturation magnetic flux density magnetic film such as garnet or ferrite, (3) is an insulator, (4) is a laminate of a high permeability metal magnetic film (1) and an insulating film (3);
(5) is a gap, (10) is a wire-wound window, and (12) is a welded glass.

As for the manufacturing method, as shown in FIG. 3, a laminated block (13) is formed as in the conventional thin film magnetic head, and a low saturation magnetic flux density magnetic film (2) is formed on the surface corresponding to the gap surface as shown in FIG. ) is formed into a film, then a narrow track groove (11) is formed, a winding groove (not shown) is formed, a gap material is applied to the gap surface, the blocks are butted, molded and cut to obtain a head chip. However, low saturation magnetic flux density magnetic film (
2) is formed on the leading edge side.

Next, the operation will be explained. In the case of reproduction, if the recording wavelength and head gap length are approximately the same, the following gear loss term becomes a dominant factor in the reproduction output.

loss term (“Magnetic Recording” by Mitsukoshi Matsumoto, p 118 (7, 49)
Formula Therefore, the gap length is less than or equal to % of the wavelength, % of the bit length
It is necessary that the following is true. For example, the shortest bit length is 0
．． If it is 3 μm, the gap length will be 0.2 μm or less.

Next, in the case of recording, while the magnetic core operates linearly, the recording current and head magnetic field are proportional to each other, but as the recording current increases to a certain extent, magnetic saturation occurs near the gap where the magnetic flux concentrates, and the magnetic field distribution is spreading. This situation can be seen in the fifth
The figure shows the flow of magnetic flux (Magnetic Recording by Mitsukoshi Matsumoto, p.
33). However, Fig. 5(a) is before saturation, Fig. 5(b)
) after saturation. In addition, this figure 5 shows the gap (5)
is enlarged to show its symmetrical half, and the y-axis is the gap (
5) perpendicularly to the sliding surface, and point O is the intersection of the y-axis and the sliding surface.

The spread of this magnetic field distribution (Figure 5(b)) is the media outlet end (
If this occurs at the trailing edge (hereinafter referred to as trailing edge), it will have an adverse effect as recording demagnetization. According to the present invention, since a magnetic material with a low saturation magnetic flux density is arranged at the leading edge, saturation occurs first on the leading edge side and a strong magnetic field can be generated with an effectively wide gap length. Since saturation is less likely to occur on the ring edge side, there is less recording demagnetization. Therefore, even if the gap length is 0.2 μm or less, a sufficient magnetic field necessary for recording can be generated, and self-recording and reproducing is possible.

In addition, the reproduction output largely depends on the magnetic permeability of the magnetic core, but in the case of the present invention, eddy current loss is sufficiently suppressed because a laminate of a metal magnetic film and an insulating film is used, and even at high frequencies of several tens of MHz, Since high magnetic permeability is ensured, a head with excellent high-frequency characteristics can be obtained.In the above embodiment, the magnetic core was composed of a laminate of a metal magnetic film and an insulating film, but when the track width is several μm, In this case, a single layer may be used since the eddy current loss is not so large even with a single layer of metal magnetic film.

Further, in the above embodiment, nothing is applied to the magnetic core on the trailing edge side, but as shown in the perspective view of FIG. 6 or the enlarged view of the sliding surface in FIG.
If a magnetic film (6) having a high saturation magnetic flux density such as e-3i is applied, an effect greater than that of the above embodiment can be obtained.

Further, in the above embodiment, the laminate is sandwiched between non-magnetic substrates, but it may be sandwiched between magnetic substrates such as Mn--Zn ferrite having high resistivity.

[Effects of the Invention] As described above, according to the present invention, most of the magnetic core is composed of a laminate of a metal magnetic film with high magnetic permeability and an insulating film, and a lower saturation magnetic flux is provided on the leading edge side of the gap. Because it uses a metal magnetic film with a high density, it can achieve a wide band of several tens of MHz and the shortest recording wavelength is 0.6, which was previously difficult.
There is an effect that high-density recording with a shortest bit length of 0.3 μm or less can be performed with sufficiently high efficiency.

[Brief explanation of the drawing]

1 is a perspective view of a thin film magnetic head according to an embodiment of the present invention, FIG. 2 is an enlarged view of the sliding surface of the thin film magnetic head of FIG. 1, and FIGS. 3 and 4 are shown in FIG. 1. FIG. 5 is a diagram showing the distribution of magnetic flux before and after saturation of the magnetic flux; FIG. 6 is a perspective view of a thin-film magnetic head according to another embodiment; FIG. 6 is an enlarged view of the sliding surface of the thin film magnetic head shown in FIG. 6, and FIG. 8 is a perspective view of the conventional thin film magnetic head. In the figure, (1) is a metal magnetic film with high magnetic permeability, (2) is a magnetic film with low saturation magnetic flux density, (3) is an insulating film, and (4) is (1).
The laminated body (5) in which (3) and (3) are stacked alternately has an operating gap,
(6) is a magnetic film with high saturation magnetic flux density, (10) is a wire-wound window,
(11) is a narrow track groove, (12) is a welded glass, (2)
2) is low melting point glass, (23) is crystallized glass, (24
) is a non-magnetic substrate. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa Diagram 4: Serious Waste Diagram Diagram Diagram Diagram

Claims (1)

[Claims] (1) Non-magnetic layered magnetic material or single-layer magnetic material with a width equivalent to or larger than the track width formed by alternately laminating thin films made of a metal magnetic material with high magnetic permeability and thin films made of an insulating material. A pair of magnetic core halves sandwiched between substrates or oxide magnetic substrates is formed with a magnetic film having a low saturation magnetic flux density on the gap forming surface on the medium inflow side (hereinafter referred to as the leading edge), and then the magnetic core halves are sandwiched between substrates or oxide magnetic substrates. A thin film magnetic head characterized by being bonded.