JPH01125717A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a C/N characteristic at a short wavelength by disposing a thin ferromagnetic metallic film on a smooth high-polymer film and disposing a plasma-polymerized film contg. an oily polymer thereon, then disposing a thin hard-carbon film thereon. CONSTITUTION:The thin ferromagnetic metallic film 2 is disposed on the smooth high-polymer film 1 and the plasma-polymerized film 3 contg. the oily polymer is disposed thereon, then the thin hard-carbon film 4 is disposed thereon. The microuniformity of the thin ferromagnetic metallic film 2 is thereby improved and the C/N in the short wavelength region is assured without increasing noises even if the recording wavelength is shorter. The necessary durability is obtd. by the laminated structure of the plasma-polymerized film and the thin hard- carbon film 4. All these films are thin and have the strong lateral bond with each other and, therefore, the spacing loss is decreased and the improvement in the C/N is contributed also by such decrease.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film suitable for high-density magnetic recording and reproduction.

BACKGROUND OF THE INVENTION It is becoming difficult to ensure a sufficient C/N ratio for magnetic recording, which has been widely used as a magnetic recording layer in the past, as the wavelength becomes shorter and shorter in the future.
Instead, it is expected that magnetic recording media with magnetic recording layers made of ferromagnetic metal thin films such as G o-Or and G o -N i-0 will be put to practical use [IEE Transactions on Magnetics (II! ,F,ETRANS
ACTIONS ON MAGNETIC8) VO
l, MAG, 21, No-3, 1217-1220 (
(1985)]. In order to put a magnetic recording medium with such a configuration into practical use, it is essential to ensure durability during high-speed sliding movement with the magnetic head, and an increasing number of proposals for improvement from this point of view have been made [for example, Japanese Patent Application Laid-Open No. 1983-1990 Publication No. 88704, 59-1
Publication No. 21631.

See Publication No. 59-171026, Publication No. 62-197917, etc.]. Among them, the method of forming fine irregularities on the magnetic recording layer is attracting a lot of attention for its effect of improving the durability of the magnetic recording layer [IKKETRANSACTIONS on Magnetics]
S ON MAGNETIC8) Vol, MAG-
21, Nos, 1624-1 s2θ (1986)].

Problems to be Solved by the Invention However, when a polymer film is coated with Mu12031Si,
n2. A magnetic recording medium has a fine particle coating layer on which fine particles such as CaO polyethylene spheres are coated and fixed, a ferromagnetic metal thin film is deposited by electron beam evaporation, sputtering, etc., and a protective lubricant layer is provided. If it is less than 0.6 μm, the C/N ratio is insufficient and improvement is desired.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a magnetic recording medium with a good Ct/N at short wavelengths.

Means for Solving the Problems In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has a ferromagnetic metal thin film arranged on a smooth polymer film, and a plasma polymerized film containing an oily polymer on top of the ferromagnetic metal thin film. on which a hard carbon thin film is placed.

Effect The magnetic recording medium of the present invention has the above-described structure, which improves the microscopic uniformity of the ferromagnetic metal thin film, so that noise does not increase even when the recording wavelength becomes short. The required durability is achieved by the laminated structure of plasma polymerized film and hard carbon thin film, and the thickness of both films is thin and the lateral bond is strong, so the required durability is achieved by spacing. The ability to improve loss also works to improve j/N.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. The figure is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In the figure, 1 is a polymer film such as polyethylene terephthalate, polyphenylene sulfide, polyimide, polyether sulfo/, polyamideimide, polyethylene naphthalate, etc., with an average roughness of 10 to 60 and a maximum roughness of 100. It is necessary to have a smoothness of . 2 is Co-Ni, Co-Cu, C
o-0r.

Go-Ta, Co-Mo, Co-W, C
o-0, Co-Ni-0.

A ferromagnetic metal thin film such as Co-0r-Nb or Co-0r-Rh, regardless of the direction of the axis of easy magnetization, and may be manufactured by any thin film forming method such as electron beam evaporation or sputtering. If necessary, it may be formed through a soft magnetic layer such as permalloy underlayer made of titanium, germanium, chromium, etc. 3 is a plasma-polymerized membrane containing oily polymers, such as hydrocarbon gas monomers and fluorine compound monomers.

Starting material is a nitrogen compound monomer, etc., and the conditions are optimized using parameters such as monomer flow rate, degree of vacuum, high frequency, input power, etc., and the film thickness is in the range of 30 to 100 mm. In terms of ratio, it is preferable that 16 to 30 pieces are included in the total. 4 is a hard carbon thin film formed by graphite sputtering or hydrocarbon gas discharge decomposition, and has a thickness of 30 mm.
Preferably, the film has a thickness of 1 to 100 cm, and the reason why this film sufficiently acts as a protective film at such a thin thickness is probably because the oily polymer volatilizes during formation and is partially trapped in the hard carbon film.
This is thought to be because it contributes to the lubrication effect later on, and because the shape effect of the countless micropores improves the sustainability of the auxiliary effect of the lubrication effect. 6 is a lubricant such as a fatty acid or a fluorine compound, but it is not always necessary, but in order to use it in a wide range of environmental conditions and obtain stable characteristics, it is preferable to use a lubricant of about 308 to 70 in terms of uniform thickness. .

Hereinafter, one embodiment of the present invention will be described in more detail in comparison with a comparative example. Prepare a polyethylene terephthalate film with a thickness of 13 μm, with an average roughness of 20 people and a maximum roughness of 66 people.

After performing electron beam irradiation treatment at 20 μm/d, Co-Cr (Or20.
5Wt) A perpendicular magnetization film with a thickness of 0.1 μm was formed, and perfluorocyclobutane was introduced thereon at a rate of 1tso cc/Win.
2).

By glow discharge of 1.2 (Kw), 60 people formed a plasma polymerized thin film containing an oily polymer of 19% by weight,
Continuing to target graphite, Mr1H2
= 0.02 (Torr), Ar:H2=1:3
Sixty diamond-shaped hard carbon thin films were formed by sputtering using a glow discharge of 13.66 (MH2) and 1.5 (KW). This membrane had a large number of pores, with an approximate area ratio of 23%. Finally, the film was evacuated at 1×1o-' (Torr) for one day and night using a vacuum evaporation method, and then barfluorostearic acid was evaporated by 40 people to form a magnetic tape with a width of 8 mm.

On the other hand, in a comparative example, 160 people in diameter were placed on the same film.
20. After arranging 10 particles/(μm)2, a 0.1 μm Co-Or perpendicular magnetization film as in the example was placed, 130 hard carbon thin films were placed, and perfluorostearic acid was evaporated by 40 people. A magnetic tape with a width of 8 mm was prepared. O by an 8mm video deck modified from both tapes.
/N was compared.

A pit length of 0.23 μm is achieved using an amorphous alloy sputter laminated ring head with a gap length of 0.14 μm.
A rectangular wave was recorded with a rank width of 7 μm, and the C/N in the band s (MHz) was 3.9 (dB) better in the example than in the comparative example, and when the pit length became 0.1 μm, the difference was was enlarged, and the example was better by a, 6 (dB). When comparing the stealth characteristics in terms of the time required for the output to drop by 2 (dB) from the initial output, it was 82 minutes for the example and 70 minutes for the comparative example. The dynamic friction coefficient after repeated running 230 times at 40° C. and 10% RH was 0.26 for the example and 0.39 for the comparative example, indicating that the stability of the example was good. The present invention also exhibits excellent characteristics in magnetic disks.

Effects of the Invention As described above, according to the present invention, the C/N is excellent in the short wavelength range.
This has the effect that a magnetic recording medium of 100% can be obtained.

[Brief explanation of the drawing]

The figure is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. 1... Polymer film, 2... Ferromagnetic metal thin film, 3... Plasma polymerized film containing an oily polymer, 4... Hard carbon thin film.

Claims (1)

[Claims] A magnetic recording medium characterized in that a ferromagnetic metal thin film is disposed on a smooth polymer film, a plasma polymerized film containing an oily polymer is disposed, and a hard carbon thin film is disposed on top of the ferromagnetic metal thin film.