JPS6192417A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability of a recording layer by providing a protective layer consisting of cobalt oxide CoO on a vertical magnetic recording layer. CONSTITUTION:The cobalt oxide protective layer of CoO is preferably the transparent or semi-transparent thin film and more preferably the case when said film is subjected to (111) face orientation to the recording layer. The CoO which is the cobalt oxide is formed by a sputtering method, vacuum deposition method, etc. in an oxidizing gaseous atmosphere using a cobalt metal as a target and evaporating source. A polyethylene terephthalate film is used as a substrate 1 and thin metallic layers 2 consisting of a nickel-iron alloy and having high magnetic permeability and vertical magnetic recording layers 3 consisting of a thin cobalt-chromium (20wt% chromium) alloy film are successively laminated by an opposed target type sputtering method on both surfaces of said base body. The protective layers 4 consisting of cobalt oxide CoO of 300Angstrom are laminated thereon by a reactive sputtering method using the cobalt metal as a target in an oxidizing gaseous atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a perpendicular magnetic recording medium, and more particularly to a thin film type perpendicular magnetic recording medium with excellent wear resistance.

[Prior art] In recent years, the demand for high-density recording has become higher and higher, and the use of a ferromagnetic metal layer as a magnetic recording layer has become increasingly popular.
A device using a cobalt-based alloy layer having perpendicular magnetic anisotropy has been proposed, such as in Japanese Patent No.-91. However, in the case of a thin-film magnetic recording medium using such a metal thin film as a magnetic recording layer, there is a drawback that it is susceptible to wear and damage and lacks durability because of the large frictional resistance with the magnetic recording head.

For this reason, various proposals have been made in the past in which organic polymers, high-hardness metals, ceramics, etc. are further provided as protective layers on ferromagnetic metal thin films.

However, the wear resistance of the thin-film type recording medium, that is, the life span of the magnetic recording medium when the magnetic recording medium is repeatedly run on a magnetic recording head, is inferior to that of conventional coating-type magnetic recording media. However, the situation is still insufficient for practical use.

[Object of the Invention] The present invention was made in view of the current situation, and its object is to provide a thin film type perpendicular magnetic recording medium with excellent wear resistance.

[Structure 8 of the Invention] That is, the present invention relates to a known thin-film perpendicular magnetic recording medium, for example, one in which a gold FX r4 FJ layer of a cobalt-based alloy having perpendicular magnetic anisotropy is formed on a substrate, or A metal layer with high magnetic permeability such as iron, permalloy, cobalt-niobium-zircon alloy, etc., and then a metal thin film layer such as a cobalt-based alloy with perpendicular magnetic anisotropy is sequentially formed thereon. As an improvement, a cobalt oxide protective layer made of coO is provided on the metal thin film layer of the perpendicular magnetic recording layer.

The CoO cobalt oxide protective layer is preferably a transparent or semi-transparent thin film, more preferably a (11
1) In the case of plane orientation.

CoQ of cobalt oxide targets cobalt metal,
It is formed by a sputtering method, a blank evaporation method, etc. in an oxidizing gas atmosphere as an evaporation source.

Furthermore, Auger electron spectroscopy (AES) and X-ray diffraction (DX) were used to analyze CoO, which is a cobalt oxide.

In the present invention, by providing a protective layer made of cobalt oxide CoO on the perpendicular magnetic recording layer, the durability of the recording layer can be greatly improved.

Examples of the present invention are shown below.

FIG. 1 shows an example of the structure of the present invention, which is a flexible double-sided perpendicular magnetic recording medium for a floppy disk.

The base 1 is a polyethylene terephthalate film with a diameter of 5.25 inches and a thickness of 50 μm, and 0.4 μm on both sides.
a thin metal layer 2 with high magnetic permeability made of a nickel-iron alloy of m;
0.4μm cobalt chromium (chromium: 20wt%
) and a perpendicular magnetic recording layer 3 made of an alloy thin film of
Similar to Publication No. 100627, layers were sequentially laminated using the facing target sputtering method, and then three layers were layered using a reactive sputtering method in an oxidizing gas atmosphere using cobalt metal as a target.
A protective layer 4 of CoO, a cobalt oxide of 0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 oxides, the protective layers 4 are laminated (Example).

Further, as a comparative example, a sample was prepared in the same manner as in the example except for the protective layer, in which chromium, silicon, tungsten oxides, and tungsten carbide were laminated by high-frequency sputtering.

The table shows the surface roughness of these samples after they were rotated 3 million times at 300 rpm using a drive device that uses a magnetic recording head that uses optical glass (BK7) for the interlocking part (part of the head slider). The results of the evaluation are shown below.

That is, durability evaluation was performed by measuring the surface roughness of the sample before and after the sliding test using a surface roughness meter (SLJRFCOM).

The center line average roughness CLA was determined using a tool (manufactured by Tokyo Seimitsu ■), and the relative surface roughness was calculated by dividing the CLA la after sliding by the CLA value before sliding.

(The following is a blank space) It is clear from the table (, u) that the cobalt oxide of the present invention Co
In the example using a protective layer of O, the surface roughness of the medium is 1
There was no change before and after the 8-motion test, which was the best result compared to any of the comparative examples, demonstrating high durability. The CoO protective layer in the example is semi-transparent or transparent, and the recording layer (
111) It was a plane-oriented sheet.

The purpose of this defense is not limited to the floppy disks and perpendicular magnetic recording media shown in the embodiments, but also applies to so-called hard disks such as aluminum disks treated with alumina oxidation.

Needless to say, it can be applied to magnetic tape.

Also, for the manufacturing method of the recording layer and the protective layer, known film forming means other than those in the examples can be applied.

[Brief explanation of drawings]

FIG. 1 is a partial side sectional view showing the structure of one embodiment of the present invention. 1: Substrate, 2: High magnetic permeability metal thin film layer. 3: Cobalt-chromium alloy thin film layer. 4: Protective layer of cobalt oxide CoO)lΣ

Claims (1)

[Claims] 1. A thin-film perpendicular magnetic recording medium in which the perpendicular magnetic recording layer is made of a metal thin film, characterized in that a cobalt oxide protective layer made of CoO is provided on the perpendicular magnetic recording layer.