JPS60113317A - Composite type vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve efficiency of recording by paying attention to a magnetic film of high magnetic permeability that acts as a part of an auxiliary magnetic pole exciting type head and specifying the permeability of this magnetic film of high magnetic permeability. CONSTITUTION:A composite type vertical magnetic medium 14 is constituted by piling up a magnetic film of high magnetic permeability 12 and a vertical magnetizing film 13 successively on a substrate 11 made of non-magnetic material. A main magnetic pole 15 made of the magnetic film of high magnetic permeability 12 and an auxiliary magnetic pole 17 made of wound ferrite are placed opposite to the recording medium 14, and record by vertical magnetic recording is reproduced. The magnetic permeability of the magnetic film of high magnetic permeability 12 is made 750-2,000.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a perpendicular magnetic recording medium, particularly a perpendicular magnetic recording medium used in combination with an auxiliary pole excitation type head comprising a main pole made of a high permeability magnetic thin film and an auxiliary pole having a wire wound thereon. The present invention relates to a composite perpendicular magnetic recording medium comprising a perpendicularly magnetized film made of a magnetic material whose axis of easy magnetization exists in a direction perpendicular to the film surface, and a high magnetic permeability magnetic film.

BACKGROUND OF THE INVENTION Various types of perpendicular magnetic recording media and perpendicular magnetization heads have been proposed for use in perpendicular magnetic recording. Among them, as shown in FIG. 1, a substrate 1 made of a non-magnetic material
permalloy (78%) J i l 22%Fe) on top
A high permeability magnetic film 2 made of a high permeability material such as G is coated, and a perpendicular magnetization film made of a magnetic material such as co-ar whose axis of easy magnetization is perpendicular to the film surface is deposited on top of G. 8
A composite perpendicular magnetic recording medium 4 with a wire attached thereto, a main magnetic pole 5 made of a thin film of high permeability magnetic material, and an auxiliary magnetic pole 7 with a wire 6 attached thereto.
It is said that the combination with the auxiliary magnetic pole excitation type head 8 having the above is the most advantageous from the viewpoint of high-density recording and reproduction.

In a recording and reproducing system using such a composite perpendicular magnetic recording medium and an auxiliary pole excitation type head 8, a magnetic field is generated from the auxiliary pole 7 by passing a signal current through the winding 6, and this magnetic field causes the main pole 5 to is magnetized, and the perpendicular magnetization film 3 is magnetized perpendicularly by the strong magnetic field of this main pole.

In such an auxiliary pole excitation type head 8, the interaction between the main pole 5 and the perpendicular magnetization film 8 is strong, and the magnetic flux from the main pole 5 is distributed so as to be absorbed into the perpendicular magnetization film 8, and the tip of the main pole 5 is Only the vertical magnetic field will be significantly strengthened. Further, since the spread of this perpendicular magnetic field is limited by the thickness of the main magnetic pole 5, a sharp perpendicular magnetic field is always applied to the perpendicular magnetization film 8 almost regardless of the recording level. Another advantage is that a perpendicular magnetic field can be applied correctly to the film surface of the perpendicularly magnetized film 8 almost regardless of the accuracy of the central axes of the main pole 5 and the auxiliary magnet 8ii7.

On the other hand, since the composite perpendicular magnetic recording medium 4 has a high magnetic permeability magnetic film 2 that acts as a backing layer, magnetic recording is performed using a single-layer film in which only a G perpendicularly magnetized film is formed on a substrate made of a non-magnetic material. It is known that both the recording sensitivity and the reproduction sensitivity are improved by about 10 times compared to the medium. Iwasaki and Tanabe said, “1!
In the Journal of the Communication Society of Japan (0), we report the results of analyzing the magnetic flux diagram between a composite perpendicular magnetic recording medium and an auxiliary pole-excited head using the finite element method.
Accordingly, at the center position of the perpendicularly magnetized film made of QO-Or, a perpendicular W magnetic field that is about 10 times stronger than that of a single-layer film recording medium is obtained. That is, it is known that a high permeability magnetic film has a strong interaction with the main magnetic pole and exhibits a strong magnetic concentration effect. In other words, a function equivalent to that of the auxiliary magnetic pole coming close to the back surface of the QO-Or film occurs, and the 'co-ar film comes to function as a part of the head. Furthermore, in the residual magnetization state, it cancels the magnetization on the back surface of the perpendicularly magnetized layer to form a closed magnetic path, forming a so-called horseshoe-shaped magnetization mode, and has the role of keeping the perpendicular magnetization in the perpendicularly magnetized film stable. In this way, it is possible to realize ultra-high density recording by combining a composite perpendicular magnetic recording medium and an auxiliary magnetic pole excitation type head.

However, in the combination of a composite perpendicular magnetic recording medium and an auxiliary pole excitation type head, the relationship between the medium constant of the recording medium and the recording performance has not been studied much in the past. "In the June 1988 Television Society Technical Bulletin, Ohmukai, Iwasaki et al. reported on the relationship between the thickness of a high permeability magnetic film and recording sensitivity and reproduction output, but there is little else. Therefore, optimal recording efficiency could not be obtained with conventional composite perpendicular recording media.

OBJECTS OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to focus on a high permeability magnetic film that acts as a part of an auxiliary magnetic pole excitation type head,
By elucidating the relationship between the magnetic permeability μ of this high magnetic permeability magnetic film and the recording sensitivity, it is an object of the present invention to provide a composite perpendicular recording medium that can significantly improve recording efficiency. Overview The present invention provides a composite magnetic recording medium comprising a perpendicularly magnetized film made of a magnetic material whose axis of easy magnetization exists in a direction perpendicular to the film surface, and a high magnetic permeability magnetic film, and a magnetic recording medium that is opposite to the perpendicularly magnetized film. A recording and reproducing system using perpendicular magnetic recording, which combines a main magnetic pole made of a high magnetic permeability magnetic thin film and an auxiliary pole excitation type head comprising a wound auxiliary magnetic pole facing the high permeability magnetic film. In a composite perpendicular magnetic recording medium used for υA,
The high magnetic permeability magnetic film has a magnetic permeability of 750 to 2000.

Example The present invention will be explained in detail below.

FIG. 2 shows a combination of a composite perpendicular magnetic recording medium and an auxiliary pole excitation head according to the present invention, in which a high permeability magnetic film 12 and a perpendicular magnetic film are placed on a substrate 11 made of a non-magnetic material. 18 are sequentially deposited to form a composite perpendicular magnetic recording medium 14.b Opposing this recording medium 14 are a main magnetic pole 15 made of a high magnetic permeability magnetic thin film, and an auxiliary magnetic pole made of ferrite having a winding 16 applied thereto. 1.7 to face each other for recording and reproduction by perpendicular magnetic recording. In such a system, considering the axis a-a' passing through the centers of the main magnetic pole 15 and the auxiliary magnetic pole 16, and noting that the gold thread is symmetrical with respect to this axis, the magnetic permeability μ of the high magnetic permeability magnetic film 12 is The relationship between this and recording efficiency was determined by model calculation using the finite element method. This basic formula uses the two-dimensional static magnetic field equation. Here, A: Two components of magnetic potential (wb/m) C: Magnetic resistivity (m/m)
H) Jo: Forced current density (A/m') B: Magnetic flux density (T). Then, by changing the magnetic permeability μ of the high magnetic permeability magnetic film 12, which is included in the formula as the reciprocal of the magnetoresistivity ν, the key point of 975! The number of contacts @y, 1o4o was divided into rectangular meshes, and the magnetic flux density B in the perpendicularly magnetized film 13 was determined by the finite element method. The results are shown in FIG. In FIG. 8, the horizontal axis shows the magnetic permeability μ of the high permeability magnetic film 12, and the vertical axis shows the magnetic flux density B in the perpendicularly magnetized film 18 in arbitrary units. From this result, as the magnetic permeability μ of the high magnetic permeability magnetic film 12 is increased, the magnitude B of the magnetic flux density B gradually increases, reaching a maximum when the magnetic permeability μ is 750 to 2000, and then increasing the magnetic permeability μ further. Conversely, as it increases, the magnetic flux density B
was found to gradually become smaller. That is,
The dependence of recording sensitivity on magnetic permeability is that magnetic permeability μ is 750 to 200.
It becomes a chevron curve with a peak at 0. In the present invention, the applied force 5 corresponds to the magnetic permeability μ of the high magnetic permeability magnetic film 12 of 750 to 200.
Set to 0. On the other hand, the magnetic permeability μ of the high magnetic permeability magnetic film of a conventional composite perpendicular magnetic recording medium is usually 700 or less.

In one embodiment of the present invention, a composite perpendicular magnetic recording medium 14 includes a high permeability magnetic film 12 made of Fe--Ni permalloy and a high-permeability magnetic film 12 made of (3o-Or Perpendicular magnetization films 18 were sequentially deposited by high frequency sputtering.The main pole 15 was made of Oo-Zr-Nb with a thickness of 1 μm.
The auxiliary magnetic pole 17 is made of a ferrite block, and the winding 16 made of copper wire is attached to the auxiliary magnetic pole 17.
was wound with 50 tans. The thickness d of the perpendicularly magnetized film 18 made of Co - and r is 0.5 μm, and the saturation magnetization Ms is approximately 400 emu/. . and the coercive force H0 is approximately 7000
．． And so.

Further, the thickness d of the high magnetic permeability magnetic film 12 made of permalloy is 0.5 μm, and the initial magnetic permeability is 200 to 1800 μm.
changed between. This initial magnetic permeability μi was varied by adjusting the negative bias voltage applied to the substrate while permalloy was being deposited by high frequency sputtering.

As a result of actually measuring the #C sensitivity and reproduction sensitivity for various values of initial magnetic permeability μm, data as shown in FIGS. 4 and 5 were obtained, respectively. Here, the recording sensitivity is a current value Nl that provides 90% of the saturated reproduction output. The playback sensitivity is shown as the reciprocal of the playback output V.

EP The experimental results shown in FIGS. 4 and 5 also show that high recording sensitivity and reproduction sensitivity can be obtained by setting the magnetic permeability μ of the high magnetic permeability magnetic film 12 to 750 to 2000. Element method. It can be seen that the results of this analysis and the actual results are in good agreement.

Effects of the Invention As described above, according to the present invention, in a combination of a composite perpendicular magnetic recording medium comprising a perpendicular magnetization film and a high permeability magnetic film and an auxiliary pole excitation type head, a composite perpendicular The magnetic permeability μ of the high magnetic permeability magnetic film of the magnetic recording medium is 750 to 2.
By setting it to 000, recording efficiency can be maximized, high recording sensitivity and reproduction sensitivity can be obtained, and this has the advantage that ultra-high density perpendicular magnetic recording can be performed.

[Brief explanation of drawings]

FIG. 1 is a diagrammatic sectional view showing a combination of a conventional composite perpendicular magnetic recording medium and an auxiliary pole excitation type head, and FIG. 2 is a diagrammatic sectional view showing a combination of a conventional composite perpendicular magnetic recording medium and an auxiliary pole excitation type head. A diagrammatic cross-sectional view showing the combination, Figure 3 is a graph showing the relationship between the magnetic permeability of a high permeability magnetic film and the magnetic flux density in a perpendicularly magnetized film analyzed by the finite element method, Figures 4 and □ 5 The figures are graphs showing the relationship between the initial magnetic permeability of the high magnetic permeability magnetic film of the composite perpendicular magnetic recording medium of the present invention and the recording sensitivity and reproduction sensitivity, respectively. 11... Non-magnetic substrate 12... High magnetic permeability magnetic film 1
8... Perpendicular magnetization film 14... Composite perpendicular recording medium 15... Main magnetic pole 16... Winding 18... Auxiliary magnetic pole.

Claims (1)

[Claims] 1. A composite magnetic recording medium comprising a perpendicular magnetization film made of a magnetic material whose axis of easy magnetization exists in a direction perpendicular to the film surface, and a high permeability magnetic film, and a high permeability magnetic film opposite to the perpendicular magnetization film. A composite perpendicular head used in a recording/reproducing system using perpendicular magnetic recording, which combines a main pole made of a magnetic thin film with high magnetic permeability and an auxiliary pole excitation type head having an auxiliary pole facing the high permeability magnetic film and provided with a wire. A composite perpendicular magnetic recording medium, characterized in that the high magnetic permeability magnetic film has a magnetic permeability of 750 to 2000.