JPH0354720A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve C/N by incorporating one of Zn, Cd, Ru and Re by 1 - 3at.% as an additive element into Co-O or Co-Ni-O. CONSTITUTION:One element of Zn, Cd, Ru and Re is incorporated by 1 - 3at.% into Co-O or Co-Ni-O perpendicular magnetization film 3. With <=1at.% addition, enough improvement in crystallinity can not be obtained in film formation at near room temp., while with >=3at.% addition, crystallinity is improved but noise increases causing decrease C/N. By this constitution, the c-axis orientation of Co can be improved and thus, orientation of the perpendicular magnetization film 3 can be improved to give good characteristics even at low temp. Thereby, the obtd. medium has excellent C/N and durability for perpendicular magnetic recording.

Description

DETAILED DESCRIPTION OF THE INVENTION (2) (3) Field of Industrial Application 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 a method for manufacturing the same.

Conventional technology Efforts are being made to improve recording density in order to miniaturize and improve the performance of recording and reproducing equipment, and recently there has been a long-awaited desire to put ferromagnetic metal thin films into practical use as magnetic recording layers. [IEEE TRANSACTIO
NS ONMAGNETICS) Vol. MAG-2
1 No-3, P. P. 1217-1220 (19
85)].

There are many possible combinations of materials for ferromagnetic metal thin films, but only a few have been shown to have realistic possibilities, and C
Perpendicularly magnetized films such as o-Cr [Japanese Patent Publication No. 58-91, JP-A-61-120331], Co-Ni, Co-
Obliquely deposited film or wet plating film such as Ni-0 [Special Publication Publication No. 41
-19389 Publication, Japanese Patent Application Laid-Open No. 53-42010]
For the purpose of practical application, research has recently focused exclusively on the development of protective lubricant layers. Currently, a ferromagnetic metal thin film is deposited on a polymer film such as a polyethylene terephthalate film directly or after applying an undercoat such as fine particles, using an electron beam evaporation method or a sputtering method. A method of applying and drying a solution containing a lubricant such as ether [JP-A-57-1
No. 79948, Japanese Unexamined Patent Publication No. 178718/1983, and disposing a lubricant through an oxide film
1830, a combination of a carbon film and a fluorocarbon system [Japanese Patent Application Laid-Open No. 142525/1984], etc., has been put into practical use in some magnetic disks, although the carbon film is still thick, and the carbon quality has been improved. Further research has progressed, and the usefulness of increasing hardness [US Pat. No. 4,717,622] has come to be known.

Problems to be Solved by the Invention However, although perpendicularly magnetized films such as Co-Cr have the principle advantage of being free from self-demagnetization at short wavelengths, it is necessary to heat the polymer film in order to obtain good characteristics. Because of this, a heat-resistant film such as polyimide film is required, and it is difficult to secure the tightness during high-speed sliding with the magnetic head, and there are also difficulties in winding technology, which may cause wrinkles. Thermal damage tends to cause defects such as envelope failure and Do generation, and improvements have been desired. The present invention was made in view of the above circumstances,
C has recently attracted attention as a low-temperature, high-performance perpendicular magnetization film.
o-0 perpendicular magnetization film (IEEE Transactions
on Magnetics Vol. M.A.G.
-20, 768 (1984)) by further improving the C/N of Co--Cr perpendicular magnetization film and achieving the same recording performance even when the film is formed on polyester film at low temperature. It provides a recording medium.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention contains Zn as an additive element to Co-0 or Co-Ni-0.
, Cd. Ru. The magnetic recording layer is a perpendicularly magnetized film containing ~3 at% of Re.

Effect The magnetic recording medium of the present invention has the above-described structure, and (2) C
The C-axis orientation of o is improved, the orientation as a perpendicular magnetization film is improved, and sufficient characteristics can be achieved even at low temperatures.

Examples Hereinafter, the present invention will be explained with reference to the drawings. An example will be explained.

[Embodiment 1] FIG. 1 is an enlarged sectional view of a magnetic recording medium according to a first embodiment of the present invention. In Figure 1, l is polyethylene terephthalate. Polymer film such as polyethylene naphthalate polyphenylene sulfide, polyether ether ketone, polyimide, etc. 2 is Tie2, CrzO3, ZrO2
, Ta20sSiO2, polyamideimide, polyethylene, etc., are selected from a diameter range of 50 to 300 particles, and the particle size is 10 particles/(μm)2 to 100 particles/(μm).
m) It is a fine particle coating layer which is dispersed and fixed in a density range of 2. 3 contains Zn.3 in the Co-0 or Co-Ni-0 perpendicular magnetization film. Cd, Ru. It is strained to contain 1 to 3 at% of one of the elements of Re. 1a
If it is less than t%, the effect of improving crystallinity is insufficient when forming a film near room temperature, and if it is more than 3at%, noise will increase, and even if there is an effect of improving crystallinity, it will not lead to an improvement in C/N. There is a preferred range.

Either the sputtering method or the electron beam evaporation method is suitable for forming such a thin film, and in general, the sputtering method is more suitable when the target is a disk, and the electron beam evaporation method is more suitable when the target is a tape. It can be said that it is desirable. 4 is a protective lubricating layer, which may be optimized by combining a plasma polymerized film, a plasma CVD film, a fatty acid, a perfluorinated polyether, etc. to balance required durability and spacing loss.

Examples of the present invention will be described in more detail below in comparison with comparative examples.

On a polyethylene terephthalate film with a thickness of 12 μm, 10 pieces/(μm) of Cr203 fine particles with a diameter of 100
)2 arrangement, Co-a, Co-Ni - α (α is Zn, Cd
, Ru, Re(')) as the target, A
r+02 partial pressure to O. O O 1~0.01 (Torr
)Ar: H2=varied in the range of 1 to 4.5, 13.56
(MHz) Sputtering was performed at 1.15 to 1.95 (kw) to form a perpendicular magnetization film with a thickness of 0.2 μm. At that time, the medium temperature of the cylindrical can with a diameter of 50 ann was kept constant at 20°C. On the perpendicular magnetization film, 1.2 (■/rd) of Fomblin Z-25 (manufactured by Montageson) was applied to give an 8 mm tab.

Comparative examples were also made into tapes using the same procedure, and each was evaluated using a modified 8 mm VTR. The head used was a laminated alloy head with a gap length of 0.2 μm and a wavelength of 0.2 μm.
Digital recording was performed at 33 μm and the C/N was set to 15 (MHz
) The results of the band comparison and the tape conditions are summarized in Table 1.

(Left below) [Example 2] Another means to solve the problem is to use Co or Co-Ni.
The magnetic recording layer is a perpendicularly magnetized film having a magnetic diluent element mainly of oxygen and an additive element of 0.3 to 1 at% of Gd, Tb, or Ho. Due to the above structure, the magnetic recording medium of the present invention has (2) Co
The C-axis alignment property is improved, and the alignment property as a perpendicular magnetization film is improved, and the densely formed surface oxide films of Gd, Tb, and Ho provide good magnetic separation and reduce noise at short wavelengths. The improvement will result in a total C/N improvement.

Most of the elements described in the first embodiment can be used. Here, the magnetic recording layer will be explained in detail.

Example 1 and (2) Co or Co-Ni is used as the base and the magnetism is diluted with oxygen, but the added element is either Gd, Tb, or Ho, and the amount added is 0.3 to 1.
The difference is that the range is at %.

If the amount added is less than 0.3 at%, the C pongee improvement effect is small;
In addition, the magnetic separation in the surface oxide layer is insufficient and the noise is non-uniform, and if it exceeds 1 at%, a decrease in durability is seen, probably due to a decrease in the hardness of the oxide layer, so this range is selected. It is preferable.

Examples of the present invention will be described in more detail below in comparison with comparative examples.

16 pieces/(μm) of Zr02 fine particles with a diameter of 120A on a polyethylene naphthalate film with a thickness of 10.2μm
(2) Co or Co-Ni evaporation source with Gd, Ho
, Tb was supplied while changing the amount added, and the oxygen partial pressure was increased to 2.
Electron beam evaporation was performed in the range of X10-3 to 4X10-3 (Torr).

The film was deposited along a cylindrical can with a diameter of 50 cm (can temperature 30°C) at an incident angle of 5° to 25°.
A 2 μm perpendicularly magnetized film was formed, and 1 (■#) of KRYTOX-15 7FSM manufactured by DuPont was applied thereon to obtain a tape with a width of 8 mm.

In the comparative example, a film with a diameter of 12 mm was placed on a polyimide film with a thickness of 8 μm.
A cylindrical can with a diameter of 50 CII+ was heated to 260°C, and Co-Cr (Cr21 at%) was deposited by electron beam at an incident angle of 5°. added.

Table 2 shows the results of comparing the C/'N and still characteristics of each tape in the same manner as in the first example.

(Left below) [Example 3 Another means to solve the problem is (2) Co or Co-Ni
The magnetic diluent element is mainly oxygen, and when the layer is divided into two in the thickness direction, the oxygen concentration in the upper layer is 1.5 in the lower layer.
The magnetic recording layer is a perpendicular magnetization film having a magnetic field of 5 to 2.5 times. With the above-described configuration, the magnetic recording medium of the present invention effectively hardens the sliding surface with the magnetic head and improves durability, so spacing loss due to the thickness of the protective film can be improved, and magnetic separation on the upper layer side Since the ratio becomes better and the noise is also improved, overall C/N and durability improvements are achieved.

FIG. 2 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention. In Figure 2, 5 is perpendicularly magnetizable Co-0 or Co-
The particle size is 1.5 to 2.5 times that of the columnar fine particles constituting the Ni-0 film. Since the concentration often has a gradient in the thickness direction, the average concentration is used for comparison. In order to obtain such a ratio of concentration, the arrangement conditions of the oxygen introduction nozzle may be optimized, or oxygen and an inert gas such as Ar may be introduced through separate nozzles. (2)C
o-Ni-0 is (2) and the ratio of Co and Ni is (2)
A range of 10 to 25 at% of Co is crystalline. In the range of 25 to 30%, which is preferable for improving corrosion resistance, face-centered cubic crystals may be present depending on manufacturing conditions, and since this reduces vertical orientation, the content should be 25 at % or less. The thickness of the Co-0 or Co-Ni-O film is 0.
The range of 1 μm to 0.3 μm is preferable, and the oxygen content may be set by satisfying the ratio relationship between the upper layer and the lower layer within the range of 15 at % to 35 at % on the overall average.

Examples of the present invention will now be described in more detail in comparison with comparative examples.

11 pieces/(μm) of Eu203 fine particles with a diameter of 110 on a polyethylene terephthalate film with a thickness of 10 μm.
On top of that, a nozzle was arranged at the tip of a mask concentrically 40 meters apart from a cylindrical can with a diameter of 50 cm, and He gas was introduced from nozzle A on the side where vapor deposition started, and from nozzle B on the side where vapor deposition was completed. 02 gas was introduced, the oxygen concentration in the thickness direction was adjusted, and a Co-0 or Co-Ni-0 perpendicular magnetization film was formed.
AC was applied at 1.1 (■/rrr) to make a tape with a width of 8 mm. In the comparative example, nozzles A and B were both trial-produced by introducing oxygen gas. Using an 8mm video modified from each tape, recording and playback was performed at the shortest wavelength of 0.3μm band 15 (MHz) using a laminated alloy head with a gap length of 0.2μm, the C/N was compared, and the still characteristics were compared as durability. did.

The tape conditions and comparative data are summarized in Table 3.

(Hereinafter in the margin) Effects of the Invention As described above, according to the present invention, a magnetic recording medium for perpendicular magnetic recording having excellent C/N and durability can be obtained.

[Brief explanation of drawings]

1 and 2 are enlarged sectional views of a magnetic recording medium according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Polymer film, 2... Fine particle coating layer, 3... Perpendicular magnetization film, 5... Columnar fine particles.

Claims (3)

[Claims] (1) Zn based on Co or Co-Ni, the magnetic diluent element is mainly oxygen, and the additive element is 1 to 3 at%
, Cd, Ru, or Re as a magnetic recording layer. (2) Gd based on Co or Co-Ni, with the magnetic diluent being mainly oxygen and the additive element being 0.3 to 1 at%
, Tb, or Ho as a magnetic recording layer. (3) Perpendicular magnetization based on Co or Co-Ni, where the magnetic diluent element is mainly oxygen, and when divided into two in the thickness direction, the oxygen concentration on the upper layer side is in the range of 1.5 to 2.5 times that on the lower layer side. A magnetic recording medium characterized in that a film is used as a magnetic recording layer.