JPS6376111A - Magnetic recording medium - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to magnetic recording media, and particularly to magnetic recording media on which a magnetic film is deposited by sputtering, plating, vapor deposition, etc., to reduce media noise. The present invention relates to a magnetic recording medium suitable for improving m-magnetic conversion characteristics.

[Conventional technology]

In place of the coating-type magnetic recording media that has been mainly used in the past, "Nikkei New Materials 12-21985
pp. 24-35'', it is formed by a sputtering method, a plating method, a vapor deposition method, etc.

So-called thin film media have been developed and some are in practical use. Compared to coated media, these thin film media can have a magnetic film thickness of approximately 1710 mm, and can form a continuous film, making it easy to increase coercive force and high residual magnetic flux density, making it possible to increase recording density in a Tobioka way. It is known that it can be improved. The magnetic film materials for these thin film media include CO-based alloys (
Co-Ni (cobalt-nickel), Co-Cr (cobalt-chromium).

Co-N1-P (cobalt-nickel-phosphorus), Co-
Ni-○ (cobalt-nickel-oxygen), Co-N1-
N (cobalt-nickel to nitrogen), G o-N
i-Cr (cobalt-nickel-chromium), etc.) are commonly used.

FIG. 2 shows the dependence of medium noise on recording density in a comparison between a thin film medium and a coated medium, with the horizontal axis showing the recording density and the vertical axis showing the medium noise at each recording density.

As already reported from this figure (R, A, Bau
gh, E, S, Murdock and B, R,
Natrajam; IEEE Trans;
MAG19. pp, 1722-1724, 5ept,
1983), the noise of coated media decreases as the recording density increases, but the noise of Co-based alloy thin film media increases as the recording density increases;
It shows a tendency to decrease after reaching a peak (before and after PCI).

In addition, the value of medium noise is 2 to 3 times larger than that of coated media at high recording density (around 20 KPCI).

[Problem that the invention seeks to solve]

In the prior art described above, the Co-based alloy thin film medium has the possibility of achieving high recording density;

As shown in FIG. 2, there is a problem in that the medium noise is greater than that of coated media.

The purpose of the present invention is to improve such conventional problems and to
An object of the present invention is to provide a magnetic recording medium in which medium noise is reduced during high recording density of an o-based alloy thin film medium.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a magnetic recording medium on which a magnetic film is deposited by sputtering, plating, vapor deposition, etc., and the magnetic film is Co-based. In a magnetic recording medium made of an alloy material, the coercive force squareness ratio S+ of the magnetic film is 0.
．． The characteristic is that it is specified in the range of 68 to 0.8.

[Effect]

The B-8 curve shown in FIG. 3 is generally used as a means of expressing the magnetic characteristics of a magnetic recording medium. Furthermore, as a value representing the electromagnetic conversion characteristics of the medium, the value of b/a in Fig. 3 is generally used as the coercive force squareness ratio S'' (hereinafter referred to as S+). Conventionally, this S+ is the larger one. was considered to be in good condition as a disc.

FIG. 4 shows the relationship between the medium noise and S+ of the medium created using the above-mentioned S+ as a parameter. As seen in Figure 4, the media noise shows a strong dependence on S+, with S''=0
．． There is a tendency for a rapid increase in values of 8 or higher. This tendency is more noticeable at high recording density (20 KPCI).

FIG. 5 shows a schematic diagram of the magnetic domain structure of a Co-based alloy thin film medium.

As shown in Figure 5, in a Co-based alloy thin film medium, the magnetization reversal portion becomes a sawtooth magnetic domain due to magnetic coupling between crystal grains (Mitsuko Matsumoto, Magnetic Recording Kyoritsu Publishing PP, 157-15
8). The fact that the magnetization reversal portion becomes sawtooth and prevents a sharp change in the magnetic field is the main cause of medium noise in the Co-based alloy thin film medium.

The size of this sawtooth magnetic domain is proportional to the residual magnetic flux density Br and inversely proportional to the coercive force Hc.

In the present invention, S+ determined from Br and HcO values
By specifying the value of , noise is reduced.

〔Example〕

An embodiment of the present invention will now be described in detail with reference to the drawings.

FIG. 6 shows a general configuration of a Go alloy thin film medium.

This shows the composition of the Co-Ni sputtering medium.

The manufacturing process of such a general sputtering medium will be described below.

First, Ni-PM of approximately the lo group size is formed on an aluminum alloy (AQ-Mg) substrate by electroless plating. Next, we increase the horizontal magnetocrystalline anisotropy of the magnetic film to increase the coercive force H.
Approximately 2,000 carbon atoms are applied by sputtering to improve
Form an r layer. On the formed Cr layer, a Co--Ni film (layer), which will become a magnetic film, is formed to a thickness of about 600 nm by sputtering. Thereafter, an 0 layer, which is a coating layer for protecting these formed films, is formed by sputtering to a thickness of about 400 layers. A Co--Ni thin film medium is manufactured by the above process.

As an example of the present invention, an example of the experimental results using the composition of the magnetic film (Co-N i ) in the film configuration shown in FIG. 6 and the film forming conditions (argon gas pressure, input power) as parameters is shown in FIG. show. Note that this experiment was conducted using a DC magnetron sputtering device.

As shown in FIG. 7, S+ can be easily controlled.

FIG. 1 is a diagram showing the relationship between the coercive force squareness ratio of a magnetic film and the medium noise ratio in a thin film medium showing an embodiment of the present invention. This is the signal-to-medium noise ratio (hereinafter referred to as
It shows the relationship between S/N) and S+. Here, the recording density is 10.15°20 KPCI.

As seen in FIG. 1, the S/N ratio is 0.7 to 0.
The maximum value is between 75 and 75. In the present invention.

In order to obtain a high S/N, the value of S''' is specified between 0.68 and 0.8, taking into account the manageable width.

Note that the present invention specifies the coercive force squareness ratio S1, and is disclosed in the Examples. Membrane configuration 9 composition.

TFJ White is not limited to the film forming conditions.

As described above, in this embodiment, by specifying the S+ value, it is possible to reduce the medium noise to about 1/3 and improve the S/N by about 5 dB.6 [Effects of the Invention] As explained above. As described above, according to the present invention, the medium noise at high recording density of the Go-based alloy thin film medium is reduced.

[Brief explanation of the drawing]

Figure 1 shows the coercive force squareness ratio and S/H of an embodiment of the present invention.
Figure 2 is a diagram showing the recording density dependence of media noise, Figure 3 is a diagram showing the media magnetization curve, Figure 4 is a diagram showing the relationship between coercive force squareness ratio and media noise, Figure 5 is Go
FIG. 6 is a diagram showing an example of the film structure of a Go-based alloy thin film medium, and FIG. 7 is a diagram showing an example of experimental results in an example of the present invention. Fig. 1 Coercive force squareness ratio S” (Co-based alloy thin film body) Fig. 2 Recording density (KFO process) Fig. 3 Fig. 4 Coercive force squareness ratio S* Fig. 6 Fig. 7

Claims (1)

[Claims] 1. In a magnetic recording medium in which a magnetic film is deposited by a sputtering method, a plating method, a vapor deposition method, etc., and the magnetic film is made of a Co-based alloy material, the coercive force squareness ratio S^+ of the magnetic film is 1. A magnetic recording medium characterized by specifying a range of 0.68 to 0.8.