JPH04368611A - Intrasurface magnetic recording medium and magnetic memory device - Google Patents

Abstract

PURPOSE:To provide the intrasurface magnetic recording medium which can improve S/N as a whole of the magnetic memory device and the magnetic memory device by decreasing medium noises without lowering the reproduced signal output at the time of recording and reproducing. CONSTITUTION:A Co-Cr-Pt-Si magnetic film 3a and a Co-Cr-Pt magnetic film 3b are successively laminated via a nonmagnetic substrate film 2 on a nonmagnetic substrate 1. The medium S/N is then greatly increased without decreasing the reproduced signal output.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to magnetic disks, magnetic tapes, magnetic cards, and other longitudinal magnetic recording media for information recording, particularly to longitudinal magnetic recording media suitable for high-density information recording, and magnetic recording media using the same. Regarding storage devices.

0002

[Background Art] As the areal recording density of magnetic storage devices increases, the volume per recording bit formed on the magnetic recording medium becomes smaller, and the strength of the magnetic field leaking from the recording bits to the surface of the magnetic recording medium decreases proportionally. Become. Therefore,
When recording and reproducing a conventional longitudinal magnetic recording medium having an in-plane magnetic film at high density using a conventional magnetic head such as an MIG type or a thin-film type, a sufficient reproduced signal output cannot be obtained.

Therefore, it is clear that magnetic heads with high reproduction sensitivity using magnetoresistive elements or the like will be used in the future.

However, when using a highly sensitive magnetic head,
Not only the reproduced signal output but also the noise during reproduction caused by the magnetic recording medium (hereinafter referred to as "medium noise") is detected to a large extent.

[0005] Therefore, a longitudinal magnetic recording medium is required to have a high ratio of both reproduction signal output and medium noise (hereinafter referred to as medium S/N) during recording and reproduction.

Conventionally, in order to increase the medium S/N of Co-based alloy magnetic film media such as Co-Cr-Pt, magnetic interactions between crystal grains have been reduced by adding various non-magnetic elements such as Si. However, a method of lowering the medium noise and increasing the medium S/N has been proposed in Japanese Patent Application No. 1-231561.

[0007]

[Problems to be Solved by the Invention] However, although the above-mentioned conventional technology increases the medium S/N, when this technology is applied to a magnetic storage device having a magnetic head equipped with a magnetoresistive element, the following problems occur. There was a problem.

That is, in general, magnetic storage devices have high S
/N, it is necessary to reduce the media noise to the same level or less than the noise generated from the magnetic head and amplifier circuit system. In order to reduce the medium noise to the level required by the magnetic storage device used, it is necessary to add a correspondingly large amount of non-magnetic elements. As a result, the residual magnetization of the Co alloy magnetic film becomes small, resulting in a problem of insufficient reproduction signal output during recording and reproduction.

It is an object of the present invention to improve the S/N as a magnetic storage device by further increasing the reproduction signal output for conventionally developed longitudinal magnetic recording media with a high medium S/N.
An object of the present invention is to provide a longitudinal magnetic recording medium that can improve /N.

0010

[Means for Solving the Problems] The above object is to provide Co-Cr-Pt-Si on a non-magnetic substrate through a non-magnetic base film.
This can be achieved by forming a magnetic film and further forming a Co-Cr-Pt magnetic film thereon.

At this time, the residual magnetization of the Co-Cr-Pt-Si magnetic film is 250 emu/cc or more and 450 emu/cc.
It is desirable that the residual magnetization of the Co-Cr-Pt magnetic film is 700 emu/cc or more and 800 emu/cc or less.

Further, it is preferable that the ratio of the thickness of the Co--Cr--Pt--Si magnetic film to the thickness of the Co--Cr--Pt magnetic film is 1:1.

Furthermore, the above object can be achieved by a magnetic storage device that reproduces recorded information on this longitudinal magnetic recording medium with a magnetic head equipped with a magnetoresistive effect element.

[0014]

[Operation] Co-C is formed on a non-magnetic substrate through a non-magnetic base film.
In a conventional longitudinal magnetic recording medium formed with an r-Pt-Si magnetic film, the medium S/N improves as the amount of Si added increases, but on the other hand, the reproduced signal output gradually decreases. Figure 2 shows a conventional Co-Cr with residual magnetization of 750 emu/cc.
This figure shows how the medium S/N changes due to a decrease in residual magnetization when Si is added to a -Pt-Si magnetic film. The recording and reproducing conditions at this time are as shown in [Evaluation] below. In addition, the medium S/N has a residual magnetization of 750 emu/c.
The value at c was taken as the reference (0). From this figure, medium S
In order to increase /N, the residual magnetization of Co-Cr-Pt-Si is preferably set to 250 emu/cc or more and 450 emu/cc or less, and becomes smaller than 750 emu/cc. Therefore, the reproduced signal output decreases. The same effect can be obtained even if the Co--Cr--Pt--Si magnetic film used here has a remanent magnetization in the conventionally well-known range of 700 emu/cc or more and 800 emu/cc or less. Next, the present inventors discovered the above Co-Cr-Pt
It has been found that by forming a laminated film in which the upper layer of the -Si magnetic film is replaced with a Co-Cr-Pt magnetic film, the reproduced signal output can be increased while maintaining a high medium S/N ratio. Co
-12.5at%Cr-8.0at%Pt/Co-14
．． 4at%Cr-7.6at%Pt-3.5at%S
i The total thickness of the laminated film is fixed at 30 nm, and the upper layer of the laminated film is made of Co-12.5at%Cr-8.0at.
%Pt By changing the film thickness of the magnetic film from 0 to the total film thickness of the magnetic film,
FIG. 3 shows the results of evaluating the playback signal output and medium S/N under the recording and playback conditions shown in [Evaluation] below for a medium manufactured according to the film forming conditions described in Example 1 below. Here, the horizontal axis is the ratio of the thickness of the Co--Cr--Pt magnetic film in the upper layer to the total thickness of the magnetic film. Regarding the reproduction signal output, the vertical axis is set to the reference (0) when the horizontal axis value is 0. Regarding the medium S/N, a value of 1.0 on the horizontal axis was used as a reference (0). At this time, the total thickness of the magnetic film is 1
A similar tendency was confirmed in the range of 0 nm to 50 nm. From this figure, it can be seen that when the value on the horizontal axis is 0 to 0.5, the reproduced signal output can be increased while maintaining the medium S/N high. In particular, the Co-
Cr-Pt magnetic film thickness and lower layer Co-Cr-Pt-S
When the ratio of i to the magnetic film thickness is around 1, the improvement in the reproduced signal output while maintaining the medium S/N high is highest and desirable.

[0015]

EXAMPLES Example 1 Example 1 will be described with reference to FIG. 1 showing a cross-sectional view of a longitudinal magnetic recording medium of the present invention. Using an in-line DC magnetron sputtering device, first, a piece of tempered glass with a diameter of 95 mm and a thickness of 1.27 mm was prepared.
A chromium base film 2 with a thickness of 150 nm is formed on both sides of a disc-shaped nonmagnetic substrate 1. Next, Co-14.4at%Cr
- Thickness 1 consisting of 7.6 at% Pt - 3.5 at% Si
5 nm first magnetic film 3a, Co-12.5 at% Cr
A 15 nm thick second magnetic film 3b made of -8.0 at% Pt and a 10 nm thick carbon protective film 4 are sequentially formed to produce a magnetic disk. As for the film forming conditions, the substrate temperature was kept constant at 150°C, the argon gas pressure was 3.7 Pa when forming the chromium base film, 2.0 Pa when forming the first magnetic film and the second magnetic film, and the argon gas pressure was 2.0 Pa when forming the first magnetic film and the second magnetic film. The pressure is set to 1.3 Pa when forming the protective film. All target input power densities are maintained at 50 kW/m2.

Comparative Example 1 Another magnetic disk for comparison was prepared in the same manner as in Example 1 except that the first magnetic film 3b was omitted and the second magnetic film 3a had a thickness of 30 nm.

Example 2 Using an in-line type DC magnetron sputtering device, first, a chromium base film 2 with a thickness of 125 nm was coated on both sides of a disc-shaped nonmagnetic substrate 1 made of tempered glass and having a diameter of 95 mm and a thickness of 1.27 mm. After forming C
o-15.5at%Cr-7.5at%Pt-3.0a
16 nm thick first magnetic film 3a made of t%Si, C
A 14 nm thick second magnetic film 3b made of o-12.0 at% Cr-7.5 at% Pt and a 10 nm thick carbon protective film 4 are sequentially formed to produce a magnetic disk. As for the film forming conditions, the substrate temperature was kept constant at 100°C, and the argon gas pressure was 3.7 Pa during the formation of the chromium base film.
Both at the time of forming the first magnetic film and the second magnetic film 2.
0 Pa, and 1.3 Pa at the time of forming the carbon protective film. All target input power densities are maintained at 50 kW/m2.

Comparative Example 2 Another magnetic disk for comparison was prepared in the same manner as in Example 2, except that the first magnetic film 3b was omitted and the second magnetic film 3a had a thickness of 30 nm.

[Evaluation] Regarding the magnetic disks of Example 1 and Comparative Example 1, and Example 2 and Comparative Example 2, reproduction signal output, medium noise, and medium S
/N measurement results are shown in Tables 1 and 2, respectively. Each measurement was carried out using a thin film magnetic head with a gap length of 0.2 μm and a head flying height of 0.1 μm. The reproduced signal output is when recording at a linear recording density of 1 kFCI, and the medium noise is the noise signal generated from the medium when recording at a linear recording density of 75 kFCI. This is the result of integration over the corresponding frequency band. Reproduction signal output and medium S in Tables 1 and 2
The measured values of /N are based on each measured value in Comparative Example 1.

[0020]

[Table 1]

[0021]

[Table 2]

As is clear from Tables 1 and 2, in Examples 1 and 2 of the present invention, the magnetic film was
Compared to Comparative Examples 1 and 2 in which a single layer of o-Cr-Pt-Si magnetic film was used, the reproduction signal output can be improved by +2.5 dB or more with the medium S/N being the same or higher.

As is clear from the above description, Co--Cr--Pt--S is deposited on a non-magnetic substrate via a non-magnetic base film.
In a longitudinal magnetic recording medium in which an i magnetic film and a Co-Cr-Pt magnetic film are sequentially laminated, the medium S/N ratio can be significantly improved and the reproduced signal output can be improved.

[0024] Furthermore, the above description is based on the magnetic films constituting the magnetic recording medium, such as Co-Cr-Pt-Si magnetic films and C
The case where o-Cr-Pt magnetic films were sequentially laminated was investigated, but as a combination of this lamination, the lower layer Co-Cr-P
Instead of t-Si magnetic film, Co-Cr-Ta magnetic film or C
A similar effect can be expected when an o-Cr magnetic film or the like is used.

[0025]

Effects of the Invention The longitudinal magnetic recording medium of the present invention has a medium S/
It is possible to significantly improve N and improve reproduction signal output, and it can be widely used as a recording medium for magnetic disk devices, magnetic tape devices, flexible disk devices, and other magnetic storage devices.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a longitudinal magnetic recording medium of the present invention.

FIG. 2 is a diagram showing the effects of the longitudinal magnetic recording medium of the present invention.

FIG. 3 is a diagram showing the effects of the longitudinal magnetic recording medium of the present invention.

[Explanation of symbols]

1: Nonmagnetic substrate, 2: Nonmagnetic base film, 3a: First magnetic film, 3b: Second magnetic film, 4: Protective film.

Claims (4)

[Claims] 1. A non-magnetic substrate, a first magnetic film made of a Co-Cr-Pt-Si alloy formed on the non-magnetic substrate via a non-magnetic base film, and on the first magnetic film. 1. A longitudinal magnetic recording medium comprising a second magnetic film made of a Co-Cr-Pt alloy. 2. The residual magnetization of the first magnetic film is 250em.
u/cc or more and 450 emu/cc or less, and the second
The residual magnetization of the magnetic film is 700emu/cc or more and 800emu/cc or more.
2. The longitudinal magnetic recording medium according to claim 1, wherein the longitudinal magnetic recording medium is less than or equal to u/cc. 3. The longitudinal magnetic recording medium according to claim 1, wherein the ratio of the thicknesses of the first magnetic film and the second magnetic film is 1:1. 4. A magnetic head equipped with the longitudinal magnetic recording medium according to any one of claims 1 to 3 and a magnetoresistive element for reproducing information recorded on the longitudinal magnetic recording medium. magnetic storage device.