JPS6190323A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which has large coercive force and is suitable for high-density recording by forming a magnetic recording layer which consists of a Co-O film contg. V within a specific ratio range with respect to Co and has the axis of each magnetization perpendicular to the plane of the magnetic recording layer on a nonmagnetic base body. CONSTITUTION:The nonmagnetic base body, for example, a polyethylene terephthalate film 13 is fed from an unwinding roll 6 to a take-up roll 7 along a can 9 while the can 9 is rotated in an arrow direction. Respective vapors are generated from a Co vapor source 3 and V vapor source 4 below the aperture of a shielding plate 10 by electron guns 5. Gaseous O2 is fed from a flow rate regulator 12 through a nozzle 11 and while the inside of a device 1 is evacuated by vacuum pumps 2, 2, the perpendicular magnetic recording layer contg. 1-10atom% V in Co-O is formed on the film 13. The amt. of the V to be added is increased slightly when the oxygen partial pressure is low and the amt. of the V to be added is decreased slightly if said pressure is high. The vertical anisotropic magnetic field and coercive force are thus increased and only the saturation magnetic flux density is decreased by incorporating the adequate amt. of V into said film by which the magnetic recording medium suitable for high-density recording is obtd.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in magnetic recording layers of magnetic recording media.

[Prior art]

In recent years, in the field of magnetic recording, the demand for high-density recording has rapidly increased as equipment becomes larger in capacity and smaller in size. For this reason, many improvements and developments are being made on the recording medium surface to improve the recording density. As a means of achieving higher density, the saturation magnetic flux density (8s) of the recording medium is increased and the coercive force (Hc) is increased. Efforts are being made to reduce the demagnetizing field by reducing the thickness of the magnetic layer. In addition to such improvements in conventional in-plane magnetized media, there is a method of using a perpendicularly magnetized film whose easy magnetization direction is normal to the recording magnetic layer as a means of increasing the density. As magnetic media for perpendicular magnetic recording, sputtering, o-Cr alloy films, and coated Ba-ferrite films are well known. Alternatively, it has been found that a Co-0 film deposited by sputtering also becomes a perpendicularly magnetized film.

[Problem that the invention seeks to solve]

The BS and HC of the Go-0 film change depending on the oxygen gas pressure during film formation. As an example, FIG. 2 shows the values of 83 and Hc of a CO-0 film produced by electron beam evaporation with respect to oxygen gas pressure. In the figure, --- indicates 83", and --- indicates Hc. The perpendicular magnetization film is a Go-0 film with a BS of about 5000 Gauss or less, and
The o-0 film is an in-plane magnetization film.

As is clear from Fig. 2, the conventional method for forming a Go-0 film by vapor deposition in an oxygen atmosphere produces a film with a large Hc within the range of forming a perpendicular magnetization film that is advantageous for high-density recording. The disadvantage is that it cannot be obtained.

[Means for solving problems]

An object of the present invention is to provide a magnetic recording medium for high-density recording having a Go-0 perpendicular magnetization film with a large Hc as a magnetic recording layer.

The above objects of the present invention are achieved by the following magnetic recording medium.

That is, in a magnetic recording medium comprising a magnetic recording layer on a non-magnetic substrate, the magnetic recording layer has an axis of easy magnetization substantially perpendicular to the film surface, and V is contained in an amount of 1 to 10 atomic % relative to Go. This is a magnetic recording medium characterized by being a Co-0 film containing.

The inventors have discovered that by adding a small amount of V to a Go-0 film, a magnetic recording medium that is a perpendicularly magnetized film and has a large Hc can be obtained. The condition for perpendicular magnetization H'A is that the perpendicular anisotropic magnetic field H is equal to the demagnetizing field of the thin film 4 tMs (= Bs
) is a bigger thing. In the conventional Go-0 film, 83 was large in a large Hc range, so it could not be a perpendicularly magnetized film, but by adding a small amount of ■, HK and Hc were not reduced.

By lowering only BS, a film with large perpendicular magnetization of He can be obtained. The amount of (1) varies depending on the oxygen gas pressure during production, but is preferably 1-10% of Go in terms of atomic ratio. If it is less than 1 atomic %, the effect of lowering 83 is small, and if it exceeds 10 atomic %, IC, H
In addition to causing a decrease in H, it also does not result in a perpendicularly magnetized film, which is undesirable.Generally, when the oxygen partial pressure is low, add a larger amount of (■), and when the oxygen partial pressure is high, add less. By adjusting this, a perpendicular magnetization film with good characteristics can be obtained.

Note that the Co-0 film is formed by a vacuum evaporation method, a sputtering method, an ion blating method, or the like.

〔Example〕

Examples are shown below to further specifically explain the present invention.

Embodiment 1 FIG. 1 shows an apparatus for manufacturing a magnetic tape, which is an example of the magnetic recording medium of the present invention. The 12-thick polyethylene terephthalate film 13 that is the substrate is fed from the unwinding roller 6 via the free roller 8 to the can 9 cooled to -1°C, where a magnetic recording layer is formed, and the free roller 8
The film is then wound onto a winding roller 7. Deposited element C
o and V are housed in separate crucibles 3 and 4, respectively, and are heated and evaporated by an electron gun 5. 1 alloy of co and V
When evaporated from two crucibles, the vapor pressures of Go and V are different, resulting in a difference in composition in the length direction. Therefore, it is preferable to evaporate the oxygen gas individually as in the example, and adjust the oxygen gas to a predetermined pressure using a flow rate regulator during evaporation.
It is blown out from the nozzle 11.

Using the above device, oxygen partial pressure 4. OmTorr, 3.5m
2.2.5 for Torr and V7FtCo.
A Co-0 film containing 1.7.4.10.0°12.3 atomic % and a Go-0 film not containing ■ were formed to a thickness of 0°35 tiles.

The 83, Hc and easy magnetization direction of the produced magnetic tape are shown in Table 51.

Oxygen partial pressure 3.5 mTorr and 4. When the film is formed at OmTorr, it has a perpendicular easy axis of magnetization with a content of 15.1, 7.4, and 10.0 at%, and Hc is also 660 to 8900.
A magnetic tape with a size of e was successfully produced.

In the case of the Go-0 film that does not contain (2), the He in the range that forms a perpendicularly magnetized film is 5000e or less, and by adding (2), a perpendicularly magnetized film with a large Hc was obtained.

Figure 4 shows V made at an oxygen partial pressure of 4 mTorr.5.1
It is a hysteresis curve of this example containing atomic%. When compared with the tape manufactured under the same conditions without V shown in Figure 3, the residual magnetization in the perpendicular direction is larger than the residual magnetization in the plane, and the magnetic recording medium of the present invention has excellent perpendicular magnetization characteristics. have. In FIGS. 3 and 4, 14. I
ft is a hysteresis curve in the direction perpendicular to the medium film surface; 15.
l? is the hysteresis curve in the film plane.

Example 2 Although Example 1 was produced using the vacuum evaporation method, it was confirmed that a perpendicularly magnetized film having good recording properties could be obtained by adding ■ even when using the sputtering method. The device used was an RF magnetron spunter type, and the target was a composite target with a V tip placed on Co. The substrate is made of glass, and the substrate holder is water-cooled. The film formation rate is approximately 800A/sec,
The film thickness is about 0.4 scales. Oxygen was mixed with Ar from Subaru Ntagas using a gas flow regulator so as to have a predetermined pressure ratio, and the total pressure was 3 mTorr. 02 pressure/Ar pressure is 0.1
In the case of 2.0.14, the Go-0 film and the V-containing A Go-0 film was formed.

83 of the produced magnetic tape. Table 2 shows Hc and the direction of easy magnetization.

As in Example 1, a perpendicularly magnetized medium having good magnetic properties with a large Hc was obtained by adding (3). The amount of addition of 1 is the same in the sputtering method as in the vacuum evaporation method.
-IQ atomic % range is valid.

〔Effect of the invention〕

As explained above, V produced in a moderate oxygen atmosphere
1～! Co-0J containing 0 atom%! ! No. 2 is a perpendicular magnetic medium with a sufficiently large amount of He and has excellent magnetic properties for high-density recording.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a magnetic tape manufacturing apparatus of the present invention using a vacuum evaporation method, and FIG. 2 is a diagram of a conventional magnetic tape manufacturing apparatus using a vacuum evaporation method.
FIG. 4 is a graph showing the oxygen gas pressure dependence of the magnetic properties of the o-0 film; FIG. 3 is a hysteresis curve of a comparative sample; and FIG. ■...Vacuum chamber, 2...Vacuum pump, 3.
...Go evaporation source 4...V evaporation source, 5...electron gun, 6...unwinding roller. 7... Winding roller, 8... Free roller, 9
...can, lO...shiyahei board, 11
...Oxygen blowing nozzle, 12...Gas flow rate regulator, 13...Polyethylene terephthalate film, +4
．． II (...Hysteresis curve in the direction perpendicular to the medium surface, 1
5.17...Hysteresis curve in the medium plane. Figure 2 # Grave gas pressure (example rt) rr) Figure 3 Figure 4

Claims (1)

[Claims] In a magnetic recording medium comprising a magnetic recording layer on a non-magnetic substrate, the magnetic recording layer has a magnetic easy axis substantially perpendicular to the film surface, and contains Co containing 1 to 10 atomic % of V relative to Co.
-A magnetic recording medium characterized by being an O film.