JPH0430083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and more particularly to a perpendicular magnetic recording medium.

In conventional horizontal magnetic recording, as recording density increases, 20
~30 kilobits per inch (hereinafter abbreviated as Kbpi)
On the other hand, perpendicular magnetic recording proposed by Professor Shunichi Iwasaki has the characteristic that as the recording density increases, the cancellation of magnetization by the demagnetizing field decreases, and the maximum recording density is 200 ~ 300Kbpi
It is said that this is also possible.

Various configurations of perpendicular magnetic recording media have been considered depending on the application. An example is shown in FIG.

FIG. 1a shows the most common structure in which a high magnetic permeability film 2 is formed on a substrate 1 and a perpendicular magnetization film 3 is formed thereon. Generally, permalloy, cobalt-based amorphous film, etc. are used as the high magnetic permeability film. FIG. 1b shows a medium in which a perpendicular magnetization film 3 is formed directly on a substrate. FIG. 1c shows a medium that has been improved mainly to improve the magnetic properties of the perpendicularly magnetized film, and has an intermediate layer 4 provided between the perpendicularly magnetized film 3 and the high permeability film 2. Generally, the intermediate layer 4 is considered to be made of SiO ₂ , titanium, or the like.

The present invention relates to the basic configuration of FIG. 1b. If a perpendicularly magnetized film is directly formed on a substrate as shown in FIG. 1B, the magnetic properties will deteriorate depending on the material and surface properties of the substrate. Alternatively, in order to reduce the influence of the substrate, the thickness of the perpendicular magnetization film is increased. on the board
It is possible to form a non-magnetic film such as SiO ₂ or titanium, and then form a perpendicular magnetization film on top of it, but the former is not suitable for perpendicular magnetic recording systems where a thinner perpendicular magnetization film is preferable. However, the latter has a problem in adhesion to the substrate and the perpendicularly magnetized film.

The present invention has been made in view of this point, and its purpose is to eliminate the influence of the magnetic properties by the substrate and to create a perpendicular magnetic recording medium that has perpendicular magnetic anisotropy superior to a perpendicular magnetic single-layer medium. It is in.

Hereinafter, the present invention will be explained in detail based on specific examples.

Example 1 A non-magnetic cobalt tantalum (hereinafter abbreviated as Co-Ta) alloy film was used as the base of a perpendicularly magnetized film. When 45% by weight or more of Ta, whose basic composition is shown in FIG. 2, is mixed into Co, the Co--Ta film becomes non-magnetic. A case in which a single-layer cobalt-chromium perpendicularly magnetized film (hereinafter abbreviated as Co-Cr film) is formed directly on a glass substrate, and a case in which a non-magnetic Co-Ta film according to the present invention is used as a base and a Co-Cr film is formed on it. FIG. 3 shows the relationship between the Co--Cr film thickness and the Co--Cr perpendicular magnetic anisotropy field (hereinafter abbreviated as Hk) in the case of forming the Co--Cr film. The Co-Ta nonmagnetic film is Co ₅₀ Cr ₅₀ (wt%) and the film thickness is 0.2 μm.
It is. Hk was measured using a torque meter. The dotted line 6 shows the characteristics of the perpendicularly magnetized single layer film, and the solid line 7 shows the characteristics of the perpendicularly magnetized double layer film provided with the nonmagnetic Co-Ta as the base according to the present invention. Especially Co-
The effects of the present invention are obvious when the Cr film is 0.3 μm or less.

Example 2 When aluminum treated with alumina oxidation is used as the substrate and the thickness of the Co-Cr perpendicular magnetization film is fixed at 0.2 μm, the thickness of the non-magnetic Co-Ta film and the Co-
Figure 4 shows the relationship between the perpendicular magnetic anisotropy field of the Cr film. Directly formed on alumina substrate, film thickness is 0.2μ
In the case of a Co-Cr film as thin as m, there is almost no perpendicular magnetic anisotropy, whereas when a Co _-50 Ta- ₅₀ non-magnetic film is formed on the base, as the Co-Ta non-magnetic film becomes thicker, its perpendicular magnetic anisotropy increases. The perpendicular magnetic anisotropy of the overlying Co-Cr film increased rapidly.

Note that the nonmagnetic cobalt alloy film is not limited to cobalt tantalum. In addition, nonmagnetic cobalt chromium, nonmagnetic cobalt niobium, nonmagnetic cobalt tungsten, nonmagnetic cobalt molybdenum, nonmagnetic cobalt panadium, nonmagnetic cobalt titanium, and even nonmagnetic cobalt ternary systems may be used. In addition, in a magnetic head with a main magnetic pole and an auxiliary magnetic pole facing each other,
If a high magnetic permeability film is provided under the Co-Cr film, the recording and reproducing efficiency will increase, but if high magnetic permeability amorphous Co-Ta is provided instead of permalloy etc., not only will the recording and reproducing efficiency increase, but the Co-Cr Needless to say, the perpendicular magnetic anisotropy and durability of the material also increase.

As described above, the perpendicular magnetic recording medium of the present invention is characterized in that a non-magnetic cobalt-based alloy film is formed as an underlayer on a substrate, and a perpendicular magnetization film is formed on the non-magnetic cobalt-based alloy film. Therefore, it is possible to provide a perpendicular magnetic recording medium that does not impede the magnetic anisotropy of the perpendicularly magnetized film, regardless of the material of the substrate.

Furthermore, even when the Co-Cr film thickness is as thin as 0.2 μm,
There is also the effect that Hk>5KOe.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of a perpendicular magnetic recording medium, and FIG. 2 is a diagram showing a configuration according to the present invention. Figure 3 is a diagram in which the perpendicular magnetic anisotropy field is blotted against the film thickness of cobalt chromium in a cobalt chromium single layer film and a cobalt chromium double layer film with non-magnetic cobalt tantalum as the base according to the present invention.
The figure shows the effect of the film thickness of nonmagnetic cobalt tantalum according to the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... High magnetic permeability film, 3... Perpendicular magnetization film, 4... Intermediate layer, 5... Non-magnetic cobalt alloy film, 6... Magnetic properties of single layer film, 7... Two layers Magnetic properties of the film.

Claims (1)

[Claims] 1. A perpendicular magnetic recording medium, characterized in that a non-magnetic cobalt-based alloy film is formed as an underlayer on a substrate, and a perpendicular magnetization film is formed on the non-magnetic cobalt-based alloy film.