JPH05298649A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To increase the coercive force and saturation magnetic flux density of the magnetic recording layer of a magnetic recording medium, to control the effect of self-demagnetization in the magnetic recording layer at the time of high density recording and to increase recording density and reproduction output. CONSTITUTION:When a magnetic recording layer 31 is formed on a nonmagnetic substrate 11 with an underlayer 12 in-between to obtain a magnetic recording medium, the magnetic recording layer 31 is composed of a first magnetic film 32 having high coercive force, a second magnetic film 33 having high saturation magnetic flux density and a third magnetic film 34 having high coercive force laminated on the underlayer 12 in order.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal magnetic recording type magnetic recording medium used in a magnetic disk device, and more particularly to a magnetic recording medium suitable for high density recording.

In recent years, due to an increase in the amount of information processing in a computer system, the capacity and size of a magnetic disk device have been increased, and high density recording has been demanded. Along with this, a magnetic recording medium of a horizontal magnetic recording system (hereinafter, abbreviated as a horizontal magnetic recording medium) having magnetic anisotropy in a horizontal plane of a magnetic recording layer which is generally widely used is also recorded at high density. In this horizontal magnetic recording medium, as the recording density becomes higher, the region of the magnetic recording layer that is magnetized continuously in the horizontal direction repels the adjacent magnetized region and weakens the magnetization of each other, so-called self-demagnetization effect. Becomes noticeable, the limit for high-density recording occurs, and the reproduction output also tends to decrease.

For this reason, there is a need for a medium structure that suppresses the effect of such self-demagnetization and increases the recording density and the reproduction output.

[0004]

2. Description of the Related Art Conventionally, as a horizontal magnetic recording medium capable of suppressing the influence of self-demagnetization caused by high density recording, FIG.
As shown in (a), on a non-magnetic substrate 11 made of an aluminum disc or the like that has been surface-treated by NiP plating or the like, a magnetic layer is formed in a horizontal plane via an underlayer 12 made of a Cr film having a thickness of about 0.3 μm. A magnetic recording layer 13 having a high coercive force and made of a 0.1 μm-thick Co-Cr film having anisotropy is laminated, and the surface of the magnetic recording layer 13 is covered with a lubrication protective film 14 if necessary. ing.

By providing an underlayer 12 of Cr or the like between the non-magnetic substrate 11 and the magnetic recording layer 13, a magnetic anisotropy is imparted in the in-plane horizontal direction of the magnetic recording layer 13. You can

[0006]

In the conventional horizontal magnetic recording medium described above, since the magnetic recording layer 13 has a high coercive force, a region which is magnetized continuously in the horizontal direction of the magnetic recording layer in high density recording is formed. The effect of so-called self-demagnetization, which repels the adjacent magnetic regions and weakens the mutual magnetization, is suppressed, but on the other hand, the thickness of the magnetic recording layer 13 is thin and the saturation magnetic flux density Bs is low. There is a problem that the output decreases.

Therefore, as shown in FIG. 2 (b), a 0.1 μm film having a magnetic anisotropy in the horizontal plane is formed on the non-magnetic substrate 11 via an underlayer 12 made of a Cr film having a film thickness of about 0.3 μm. Thick
A high saturation magnetic flux density magnetic recording layer 23 made of a Co-Cr film is laminated, and a lubricating protective film is formed on the surface of the magnetic recording layer 23 as needed.
When the medium structure in which 14 is covered is adopted, the reproduction output is increased, but since the magnetic recording layer 23 has a low coercive force Hc, it is easily affected by the self-demagnetization, and the magnetization bit of the recording track expands to increase the recording density. There was a problem that

Thus, the coercive force Hc and the saturation magnetic flux density Bs of the magnetic recording layer are the saturation magnetic flux density when the coercive force Hc is increased.
There is a contradictory relationship that Bs becomes low and coercive force Hc becomes low when saturation magnetic flux density Bs is increased, and it is difficult to find a film forming condition that simultaneously increases coercive force and saturation magnetic flux density when forming the magnetic recording layer. there were.

In view of the above-mentioned conventional problems, the present invention improves both the coercive force and the saturation magnetic flux density of the magnetic recording layer and suppresses the effect of self-demagnetization in the layer in high density recording to improve the recording density. Another object of the present invention is to provide a novel magnetic recording medium with improved reproduction output.

[0010]

In order to achieve the above-mentioned object, the present invention provides a magnetic recording medium comprising a non-magnetic substrate and a magnetic recording layer provided on the non-magnetic substrate via an under layer. The first magnetic film having a high coercive force, the second magnetic film having a high saturation magnetic flux density, and the third magnetic film having a high coercive force are laminated from the side.

Further, the thickness of the second magnetic film having a high saturation magnetic flux density which constitutes the magnetic recording layer is made thicker than the thickness of the first magnetic film and the third magnetic film having a high coercive force.

[0012]

According to the present invention, the first magnetic film having a thin film thickness and the high coercive force is formed on the non-magnetic substrate through the underlayer made of the Cr film.
A second magnetic film having a high saturation magnetic flux density, which is thicker than the first magnetic film, is formed on the magnetic film, and a third magnetic film having a high coercive force, which is thin, is formed on the second magnetic film, like the first magnetic film. By providing a magnetic recording layer having a film structure in which magnetic films are laminated, it is possible to realize a magnetic recording layer having a high coercive force and a high saturation magnetic flux density as a whole.

Therefore, the influence of self-demagnetization at the time of high-density recording in the thin and high coercive force first magnetic film and the third magnetic film is suppressed, and the first and third magnetic films are used. The spread of the recording magnetization bid in the second magnetic film having a high film thickness and a high saturation magnetic flux density is suppressed, and the recording density is improved.

Further, since the saturation magnetic flux density of the thick second magnetic film occupying most of the thickness of the magnetic recording layer is high, a high reproduction output can be obtained.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a magnetic recording medium according to the present invention.

In the figure, reference numeral 11 denotes a non-magnetic substrate made of an aluminum disk having a support hole at the center and surface-treated by NiP plating or the like.
A thin first magnetic film 32 having a high coercive force and a Co-Cr film having a thickness of 0.03 μm and having magnetic anisotropy in a horizontal plane through an underlayer 12 made of a Cr film having a thickness of about μm. , A second thick film having a high saturation magnetic flux density and made of a 0.05 μm thick Co-Cr film having magnetic anisotropy in the horizontal plane on the first magnetic film 32.
A magnetic film 33 and the first magnetic film on the second magnetic film 33.
Thin third magnetic film with high coercive force consisting of 0.03-μm thick Co-Cr film having magnetic anisotropy in horizontal plane similar to 32
The magnetic recording layer 31 having a film structure in which 34 layers are stacked is provided.

If necessary, the surface of the third magnetic film 34, that is, the surface of the magnetic recording layer 31 having the film structure is covered with a lubricating protective film 14. By using the magnetic recording medium having such a structure, the coercive force Hc and the saturation magnetic flux density Bs as a whole of the magnetic recording layer 31 having the film structure are increased, and the self-demagnetization during high-density recording in the layer is suppressed. The influence can be suppressed and the recording density and the reproduction output can be increased.

In order to form the first magnetic film 32 and the third magnetic film 34 of the Co--Cr film having a high coercive force and a small film thickness, for example, when the sputtering method is used, the substrate temperature is raised. Alternatively, it can be realized by applying sputter film forming conditions such as lowering the sputtering gas pressure, or by using a Co—Cr film or the like containing Pt in an amount of several wt%.

Further, the formation of the second magnetic film 33 having a high saturation magnetic flux density and having a large thickness can be realized by using a Co-Cr film having a high Co content, or the like. .. In the present embodiment, an example in which a Co-Cr film is used for the magnetic recording layer constituted by the three-layer film of the first, second and third magnetic films has been described, but the present invention is not limited to this example. For example, a Co-Ni film or the like can be used.

Table 1 shows a magnetic recording medium having a three-layer magnetic recording layer of the present invention (Example), a magnetic recording medium having a conventional magnetic recording layer having a high coercive force (Conventional Example 1), and a conventional high saturation. Magnetic properties such as coercive force Hc and saturation magnetic flux density Bs with a magnetic recording medium having a magnetic recording layer of magnetic flux density (conventional example 2) are shown.

[0021]

[Table 1]

As is clear from Table 1, the conventional example 1
In this magnetic recording medium, since the coercive force Hc of the magnetic recording layer is as high as 1800 Oe, the effect of self-demagnetization during high-density recording in that layer is suppressed and the recording density is increased, but the saturation magnetic flux density Bs is Since it is as low as 9kGauss, the reproduction output decreases.

Further, in the magnetic recording medium of Conventional Example 2, the saturation magnetic flux density Bs is 16 kGauss, which is higher than that in the magnetic recording medium of Conventional Example 1, so that the reproduction output is increased, but the coercive force Hc is 1000 Oe. Since it is low, the influence of self-demagnetization during high-density recording in the layer becomes remarkable, and the recording density decreases.

In contrast to the conventional examples 1 and 2, in the magnetic recording medium of the present example, the coercive force Hc of the first magnetic film 32 and the third magnetic film 34 forming the magnetic recording layer 31 is as high as 1800 Oe. For,
Since the influence of self-demagnetization in the film is suppressed, high density recording can be realized.

The saturation magnetic flux density Bs of the second magnetic film 33 is 16
Since it is higher than kGauss and the first magnetic film 32 and the third magnetic film 34, it is possible to improve the recording / reproducing characteristics such that the decrease in reproduction output is eliminated and a high output is obtained.

Furthermore, in the above embodiments, an example in which the magnetic recording layer has a three-layer film structure has been described, but the present invention is not limited to such a three-layer film structure. The surface is covered with a thin magnetic film of high coercive force,
And a range satisfying the basic condition that a high coercive force magnetic film having a thickness smaller than the film thickness of the high saturation magnetic flux density magnetic film is provided on the front and back surfaces of the thick film of the high saturation magnetic flux density magnetic film. Thus, a magnetic recording layer having a high coercive force and a high saturation magnetic flux density can be realized even when various combinations of the high coercive force magnetic film and the high saturation magnetic flux density magnetic film are implemented.

[0027]

As is apparent from the above description, according to the magnetic recording medium of the present invention, a magnetic recording layer having a high coercive force and a high saturation magnetic flux density can be realized. High reproduction output is obtained, and recording / reproduction characteristics are improved, which greatly contributes to high reliability of not only the magnetic recording medium but also the magnetic disk device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a magnetic recording medium of the present invention.

FIG. 2 is a cross-sectional view of essential parts for explaining two examples of conventional magnetic recording media.

[Explanation of symbols]

 11 Nonmagnetic Substrate 12 Underlayer 14 Lubrication Protective Film 31 Magnetic Recording Layer 32 First Magnetic Film 33 Second Magnetic Film 34 Third Magnetic Film

Claims (2)

[Claims] 1. A magnetic recording medium comprising a magnetic recording layer (31) provided on a non-magnetic substrate (11) with an underlayer (12) interposed between the magnetic recording layer (31) and the underlayer. A magnetic recording medium having a film structure in which a first magnetic film (32) having a magnetic force, a second magnetic film (33) having a high saturation magnetic flux density, and a third magnetic film (34) having a high coercive force are laminated. 2. The first magnetic film (32) and the third magnetic film (34) having high coercive force, wherein the second magnetic film (33) having a high saturation magnetic flux density constituting the magnetic recording layer (31) has a film thickness of The magnetic recording medium according to claim 1, wherein the magnetic recording medium is thicker than the above.