JPS61182624A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To reproduce data at a stable high output level without modulation by providing a nonmagnetic base with numerous fine recessed and projected strips extending vertically with respect to the direction in which a head moves at recording and reproducing. CONSTITUTION:Numerous fine recessed strips vertical with respect to the recording and reproducing direction are formed at a degree of 1,000-10Angstrom on the nonmagnetic base 1, which is laminated with a soft magnetic film 1a and a vertical magnetic film 1b by a popular spatter device. Accordingly the head traveling direction is hard to be magnetized at recording and reproducing, and a stable high reproduced output can be attained with a high magnetic permeability and a far less modulation.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a perpendicular magnetic recording medium capable of high-density recording.

(Prior Art) A so-called two-layer media type perpendicular magnetic recording body in which a soft magnetic film and a perpendicular magnetic film are sequentially laminated on a non-magnetic base material surface is known.

(Problems to be Solved by the Invention) In the perpendicular magnetic recording body of the above type, during reproduction, the interaction between the soft magnetic film and the recording/reproducing head is particularly strong, and particularly during reproduction, the reproduction output is caused by the soft magnetic film. It is small in the direction of easy magnetization of the film and large in the direction of difficult magnetization. This is because the initial magnetic permeability of the soft magnetic film is small in the direction of easy magnetization and large in the direction of difficult magnetization. Therefore, for example, in the case of a disk-shaped perpendicular magnetic recording medium, when magnetic anisotropy occurs in the soft magnetic film, the initial magnetic permeability changes in the circumferential direction, that is, in the direction of movement of the head. will occur. In general, the magnetic anisotropy of a soft magnetic film is caused by various conditions at the time of production, and in particular, in an in-line sputtering device, for example, a non-magnetic disk substrate is placed on a tray in a stationary state, and the tray is moved. When applying a soft magnetic film to this by sputtering, depending on the sputtering conditions, anisotropy may occur parallel to the running direction or perpendicular to the running direction. As a result, the produced magnetic recording disk products had a problem in that they had large modulation during playback.

(Means for Solving the Problems) The present invention provides a perpendicular magnetic recording medium that solves the above problems and can be reproduced with stable high output without modulation. In a perpendicular magnetic recording body formed by sequentially laminating a magnetic film and a perpendicular magnetic film, there are countless fine irregularities on the surface of a non-magnetic base material extending in a direction perpendicular to the direction in which the head moves during recording and reproduction. It consists of provisions.

(Example) Next, examples of the present invention will be described.

The non-magnetic base material is non-magnetic aluminum or synthetic 1i1
It is made of 111 material, etc., and is the same as that used conventionally, and its shape is disc-shaped, tape-shaped, etc. mosquito)
On the surface of the non-magnetic base material, countless fine irregularities perpendicular to the recording and reproducing direction are formed by an appropriate means. Figure 1A shows a disk-shaped non-magnetic base material, a so-called disk substrate (1), in which countless grooves are formed in a direction perpendicular to the recording and reproducing direction indicated by the arrow, in other words, in the radial direction of the disk. Figure 1B shows a tape-shaped non-magnetic base material, the so-called tape substrate (1), in a direction perpendicular to the recording and reproducing direction indicated by the arrow, in other words, in a direction parallel to the width direction of the tape. groove (2)
This shows what was formed. The depth of the groove (i) is 1000
~10 people is good. In the case of a disk substrate, it is common to perform mirror finishing after forming a soft film such as NiP plating on it, but it is common practice to perform mirror finishing after forming a soft film such as NiP plating. can be done.

The grooves can be created, for example, by making scratches with a sand vapor of about 6000, or by puff polishing using a liquid in which a relatively coarse abrasive is suspended.

This can be achieved by methods such as The so-called two-layer film medium type perpendicular magnetic recording body of the present invention can be obtained by processing the base material a having a countless number of uneven stripes thus prepared using, for example, a conventional in-line sputtering apparatus in a conventional manner. Figure 2 shows the in-line sputtering device (4) in its manufacturing process, where (5) is its preparation chamber, (6) is its sputtering chamber, (7) is its unloading chamber, and (8) is its soft magnetic film forming chamber. (9) is a sputtering cathode for forming a perpendicular magnetic film, (1G is a tray, and ■ is a control valve connected to the partition chamber (5), the sputtering chamber (6), and the take-out chamber (7), respectively. Vacuum exhaust port, (+21 is for each chamber (ω(6) (7
) shows a bulkhead with opening valves at both outer ends.

Thus, in order to sequentially laminate the soft magnetic film and the perpendicularly magnetized film on the substrate a of the disk having the uneven stripes shown in FIG. , in the direction of the arrow to perform sputtering of soft magnetic material and sputtering of ferromagnetic material in the sputtering chamber (6), and as shown in the third figure, a soft magnetic film ( A perpendicular magnetic disk of the present invention having a perpendicular magnetic film (1a) and a perpendicular magnetic film (1b) is obtained.

Next, an experimental example will be explained.

The upper surface of a hollow disk-shaped M plate is plated with a former P amorphous layer to a thickness of 20 tones to form a disk substrate, and on this substrate surface,
This was immersed in water in which alumina abrasive was suspended, and polished radially from the center of the substrate using a puff cloth to form countless fine grooves extending radially.

The depth of the groove at this time was approximately 200 people. The substrate having the grooves created in this way was placed in an in-line sputtering apparatus shown in the second figure, and a 0.5I
A soft magnetic film made of No-Permalloy with a thickness of J1 and 0.2
A perpendicular magnetic film made of Co-20at
A layered perpendicular magnetic recording disk was manufactured. On the other hand, for comparison, the same disk substrate was immediately subjected to in-line sputtering without undergoing the four-line forming process, and sputtered under the same conditions as above, and the two-layer medium type was prepared using the same material and the same thickness. A perpendicular magnetic recording disk was manufactured.

These two types of disk products are recorded and reproduced at a recording density of 1 BPI using a main pole excitation type perpendicular head.
The reproduction envelope was measured.

In addition, the initial magnetic permeability measured in the circumferential direction of both was determined. The results are shown in FIGS. 4 and 5. In the figure, θ is the position on the horizontal line in the direction corresponding to the tray movement direction, which is 06,
Using this as a base line, it represents the angular position on the circumference where the head will travel from now on, rotates once, and returns to the position on the horizontal line by 36
It is set to 0°. In each figure, ■ indicates the characteristic curve of the disc of the present invention, and C indicates the characteristic curve of the conventional disc.

From these graphs, it can be seen that conventional disks without grooves on the substrate have extremely large fluctuations in both reproduction output and initial magnetic permeability.
In contrast to the waving, in the disk of the present invention in which the substrate is grooved in a predetermined direction, there is almost no fluctuation in both the reproduction output and the initial magnetic permeability, and it is recognized that the reproduction output is stable and large as a whole.

As described above, according to the present invention, a perpendicular magnetic recording body is obtained in which a soft magnetic film and a perpendicular magnetic film are sequentially laminated on a base material surface having minute unevenness lines formed perpendicular to the running direction. During recording and reproduction, the head running direction is always in the direction of difficulty in magnetization, resulting in a high initial magnetic permeability and a stable high reproduction output with almost no modulation.

[Brief explanation of the drawing]

1A and 1B are plan views of a base material of a perpendicular magnetic recording medium according to an embodiment of the present invention, FIG. 2 is a partially cutaway plan view of an embodiment of the present invention, and FIG. The figure is a partially cutaway side view of an example of an apparatus for manufacturing the product of the present invention, and FIG. 4 is a diagram showing reproduction output characteristics comparing the product of the present invention and a conventional product.
FIG. 5 is a diagram showing similar initial permeability characteristics. (1)...Nonmagnetic base material (ri...concave strip a)
... Base material with uneven stripes (1a) ... Soft magnetic film (1
b)... Perpendicular magnetic film A... Product of the present invention (4
)--Sputtering equipment! ...Reproduction output of the present invention, initial magnetic permeability 11!12 Figure 2 Figure 3 Figure 5 (θ angle

Claims (1)

[Claims] 1. In a perpendicular magnetic recording body in which a soft magnetic film and a perpendicular magnetic film are sequentially laminated on a surface of a non-magnetic base material, on the surface of the non-magnetic base material, during recording and reproduction, A perpendicular magnetic recording medium consisting of countless fine irregularities extending in a direction perpendicular to the direction in which the head moves. 2. The perpendicular magnetic recording body according to claim (1), wherein the depth of the uneven stripes is about 1000 to 10 Å.