JPH03225619A - Perpendicular magnetic recording medium - Google Patents

Abstract

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

Description

Detailed Description of the Invention A1. Purpose of the Invention [Field of Industrial Application] The present invention relates to improving the electromagnetic conversion characteristics of perpendicular magnetic recording media used in floppy disks and other magnetic disks for high-quality still videos, etc. .

[Conventional technology]

In recent years, with the demand for higher density magnetic recording, research has become active on so-called continuous magnetic thin film media (hereinafter referred to as continuous media) in which the magnetic layer is formed only of magnetic materials. Continuous media fabricated by vacuum evaporation, sputtering, or plating methods have magnetic layers that are continuous thin films, so longitudinal recording is a matter of course, and dramatic improvements in recording density are expected, especially in perpendicular magnetic recording systems. cages, various magnetic tapes,
Further, application development to various product forms such as disk-shaped recording media is underway.

On the other hand, with the recent demand for smaller floppy disks and improvements in magnetic recording technology, video signals of still images can be recorded while rotating at a cycle of 1/60 seconds, which is the time required to display one screen of television signals. So-called 2
“Still video floppy disk (hereinafter referred to as SV FD)
) has appeared. The video signal recorded on this 2''S■ FD is in principle the same as that used in a VTR, and a color signal is recorded in a low frequency region and a luminance signal is recorded in a high frequency region.

However, S■, which is a still image, is a moving VTR.
Since higher image quality is required than that of a VTR, the recording band is set wider than that of a VTR, and the horizontal resolution is set to 2 that of a standard Beta VTR.
The standard S■ has 357 lines compared to 40 lines. Furthermore, there is a high demand for higher image quality for both VTRs and SVs, and the development of two-layer high bands is progressing, and ED Beta VTRs and high band S
■ has been commercialized.

However, while the horizontal resolution of the ED Beta VTR is 560 lines, the high band S■ has only about the same resolution of 520 lines. Therefore, in order to further improve the image quality, the use of perpendicular magnetic recording media in 2''Sv FDs is being considered.

[Problem to be solved by the invention]

When performing a high-quality Sv system on a perpendicular magnetic recording medium, when considering backward compatibility with the conventional standard S system and high band S system, major changes in the recording method such as digital recording are required. A method of improving image quality can be considered in which only the recording bands of color signals and luminance signals are further widened without performing this process. However, as for the recording characteristics of perpendicular magnetic recording media, although recording and reproduction can be performed up to extremely high recording densities, the reproduction output at low recording densities is low, so conventional S
If the video signal for V is recorded and played back as is, the color signal C
There was a drawback that backward compatibility was not achieved due to the lack of /N.

That is, the electromagnetic conversion characteristics of the conventional perpendicular magnetic recording medium are as shown in FIG.
is 3 MHz~ compared to commercially available metal coating medium characteristics 5.
The output below 4 MHz is small.

As a countermeasure to this problem, as shown in CoCr perpendicular magnetic recording medium characteristic 6, in which the initial orientation layer is made thicker, measures have been considered to improve the reproduction output in the low frequency region by making the initial orientation layer of the CoCr layer thicker. As a result, in the low frequency region,
Although the characteristics are almost the same as those of commercially available metal-coated media, the reproduction output in the high frequency range is lower than that of the conventional CoCr perpendicular magnetic recording medium 4, and the advantages as a perpendicular magnetic recording medium cannot be fully exploited. There was a drawback.

An object of the present invention is to provide a perpendicular magnetic recording medium that eliminates these drawbacks and improves reproduction output in the range from low frequencies to high frequencies.

Configuration of the Invention [Means for Solving the Problems] The present invention has the following features: 1. A CoCr alloy thin film of 50% is coated on a long polymer substrate.
CoCrTa is formed on the film to a thickness of 300 to 300 cm.
This is a perpendicular magnetic recording medium characterized by forming an alloy thin film.

[Effect]

As a result of extensive studies, the present inventor found that by increasing the thickness of the initial orientation layer of a CoCr perpendicular magnetic recording medium, the longitudinal recording component of the initial orientation layer increased and the reproduction output in the low frequency region increased. It was discovered that this deteriorated the vertical alignment of the film, reducing the reproduction output in the high frequency range. Therefore, by forming a CoCr film only for the initial alignment layer and using a CO-Cr-Ta alloy that is easy to vertically align as the vertical alignment layer formed thereon, the reproduction output can be improved from the low frequency range to the high frequency range. As a result of experiments assuming that a large perpendicular magnetic recording medium could be obtained, the desired result was obtained. A detailed explanation will be given below using examples.

〔Example〕

Below, the results of an experimental comparison between the embodiment of the perpendicular magnetic recording medium of the present invention and a conventional comparative example will be explained in detail with reference to the drawings.

(Comparative Example 1) A 0.2 μm thin CoCr alloy film was formed on a 30 μm thick polyimide base film used as a polymer substrate by magnetron sputtering, and a 50 μm thick fluorine-based liquid lubricant was further applied. A conventional CoCr perpendicular magnetic recording medium coated by a spin-coating method was prototyped.

The CoCr alloy target at this time was 18.5 (Cr:w
t%) was used.

(Comparative Example 2) In Comparative Example 1, CoCr alloy film thin film was replaced with CoCr alloy film.
A CrTa alloy thin film (hereinafter the alloy thin film is simply referred to as a film) was formed. At this time, the CoCrTa alloy target was (CO
: 14 wt%, Ta: 12 wt%).

(Example 1) As shown in the cross-sectional schematic diagram of FIG. A CoCrTa film 1 with a thickness of 50 mm is formed.
A fluorine-based liquid lubricant (not shown) was applied by a spin cord method.

(Example 2) In Example 1, the thickness of the CoCr film 2 was set to 50.

(Example 3) In Example 1, the thickness of the CoCr film 2 was set to 100.

(Example 4) In Example 1, the thickness of the CoCr film 2 was set to 200.

(Example 5) In Example 1, the thickness of the CoCr film 2 was set to 300.

(Example 6) In Example 1, the thickness of the CoCr film 2 was set to 400.

(Example 7) In Example 1, the thickness of the CoCr film 2 was set to 500.

A 2″ FD was prepared for the above comparative examples and examples,
The electromagnetic conversion characteristics were measured. The results are shown in FIG. Figure 2 shows commercially available metal coating media characteristics 5, comparative example 1 characteristics 8, comparative example 2 characteristics 7, example 1 characteristics 9, example 2 characteristics 10, example 3 characteristics 11, and example 4 characteristics 12. , Example 5
Characteristic 13, Example 6 Characteristic 14, and Example 7 Characteristic 15 are shown. The magnetic head at this time has a track width of 60
μm, metal-in-gap with a gap of 0.2 μm (M
IG) head was used.

From FIG. 2, the perpendicular magnetic recording medium using a CoCrTa film of comparative example 2 characteristic 7 has the lowest reproduction output in the low frequency region, followed by the conventional perpendicular magnetic recording medium using a CoCr film of comparative example 1 characteristic 8. It can be seen that the medium is small. As seen from characteristic 10 of Example 2 to characteristic 15 of Example 7, CoCr film 2
When the thickness is 50 angstroms or more, the reproduction output in the low frequency region becomes large and reaches a level equivalent to or higher than commercially available metal coating medium characteristic 5. On the other hand, in the high frequency region, as seen from characteristic 9 of Example 1 to characteristic 13 of Example 5, it can be seen that the reproduction output becomes large when the thickness of the CoCr film 2 is 300 angstroms or less.

That is, the thickness of the CoCr film 2 is set to 50 angstroms to 3
In Examples 2 to 5 (see Characteristics 10 to 13) where the thickness was 0.00 angstroms, the reproduction output could be increased from the low frequency region to the high frequency region compared to commercially available metal coating media (see Characteristic 5). .

The purpose of the present invention is to improve the perpendicular alignment by using a CoCrTa film as a perpendicular magnetic recording medium, and the composition ratio of CO, Cr, and Ta is not specified in the present invention. Not restricted.

Effects of the Invention [Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide a perpendicular magnetic recording medium that has high reproduction output from a low frequency region to a high frequency region.

Margin below

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a perpendicular magnetic recording medium showing an embodiment of the present invention. FIG. 2 is an electromagnetic conversion characteristic diagram of a comparative example and an example of the present invention. FIG. 3 is an electromagnetic conversion characteristic diagram of a conventional C0Cr perpendicular magnetic recording medium and a commercially available metal-coated medium. 1... CoCrTa film, 2... CoCr film, 3...
・Base film, 4.8...Characteristics of conventional CoCr perpendicular magnetic recording medium (characteristics of Comparative Example 1), 5...Characteristics of commercially available metal coating media, 6...CoC with thick initial alignment layer
r Perpendicular magnetic recording medium characteristics, 7... CoCrTa perpendicular magnetic recording medium (comparative example 2 characteristics), 9... Example 1 characteristics (
CoCr film (30 people), 10...Example 2 characteristics (CoC
R layer film 50 people), 11-...Example 3 characteristics (CoCr film 100 people), 12...Example 4 characteristics (CoCr film 2
00 people), 13...Example 5 characteristics (CoCr film 300
14...Example 6 characteristics (CoCr film 400 people)
, 15--Characteristics of Example 7 (CoCr film 500 people).

Claims (1)

[Claims] 1. CoCr alloy thin film of 50 Å on a long polymer substrate
1. A perpendicular magnetic recording medium, characterized in that it is formed to a thickness of 300 Å to 300 Å, and a CoCrTa alloy thin film is formed thereon.