Magnetic recording medium

Abstract

The present invention relates to a magnetic recording medium for use in an external memory device of an information processing apparatus etc., and an object thereof is to reduce noise, achieve high coercive force, and use the substance as a magnetic recording medium for detecting signals in a magnetoresistance head. In the magnetic recording medium comprising the magnetic recording layer 25 including ferromagnetic grains 22 and a nonmagnetic substance 23, the improvement in structure comprises that the ferromagnetic grains 22 are formed to have respectively an average grain diameter of 50 nm or less and not to be overlapped in the film thickness direction and to be isolated in the direction along a layer surface, and that a product of residual magnetization and a film thickness of the magnetic recording layer 25 is less than or equal to 150 Gauss.cndot..mu.m.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a magnetic recording drive, a magnetic recording medium and a method for manufacturing the same and, more particularly, to a magnetic recording drive for use in an external memory device of an information processing apparatus, etc., a magnetic recording medium used therein and a method for manufacturing the same.2. Description of the Prior ArtIn the magnetic recording drive, improvement of the recording density has been demanded more and more with an increase of an amount of information in proportion. When recording density of the conventional magnetic recording medium is increased, a S / N ratio is degraded to cause reduction of a reproducing output and increase of noise. Therefore, the magnetic recording medium enabling a large reproducing output and low noise has been demanded.In particular, the problem is to achieve noise reduction in the magnetic recording medium since reading sensitivity has bee...

AI Technical Summary

Benefits of technology

A first object of the present invention is to provide a method for manufacturing a magnetic recording medium, which is capable of reducing noise and achieving high coercive force and is fit for a magnetoresistance head.

Therefore, since the silicon containing the magnetic material is not formed, reduction of the magnetic material may be prevented so that the magnetic recording medium having large coercive force and high recording density can be achieved. In addition, since the granular magnetic layer and the diffusion preventing layer excepting the magnetic fine grains are formed by the same substance, difference in thermal stress does not occur in the granular magnetic layer and the diffusion preventing layer. Thus, a stable layer structure can be obtained without the possibility of film exfoliation. A silicon oxide film, for example, can be listed as the nonmagnetic layer. There are iron, cobalt and nickel, for example, as the magnetic grain. Further, an adhesion between a silicon dioxide layer and a silicon substrate is extremely superior and there is no risk of a separation therebetween.

Problems solved by technology

When recording density of the conventional magnetic recording medium is increased, a S / N ratio is degraded to cause reduction of a reproducing output and increase of noise.

In particular, the problem is to achieve noise reduction in the magnetic recording medium since reading sensitivity has been extremely improved by practical use of the magnetoresistance head.

However, since a cobalt system alloy constituting the recording layer 3 is inherently a solid solution, it is difficult to isolate crystal grain of the ferromagnetic film perfectly even if segregation is accelerated by adjusting composition and manufacturing conditions.

However, even under these conditions, noise reduction and large coercive force have not been achieved since crystal grains in the magnetic recording layer are small and further partially continuous with each other in such circumstances.

As a result, it has been found that the thinned CoCr.sub.12 Ta.sub.2 is not fit for the magnetic recording layer used for high recording signal frequency.

As has been stated above, regarding a granular magnetic film (Fe-SiO.sub.2) in which magnetic fine grains are dispersed into the SiO.sub.2 film, the following problem is caused in addition to the problem of the magnetic characteristic due to crystal property of the magnetic recording film.

Thus, there are caused some problems that flatness of the surface of the layer is damaged, the layer is magnetized, or the like.

It is evident that such substrate is not adequate for heating process at a high temperature.

In this case, a thickness of the substrate must also be formed less than 0.3 mm, but it is the problem to use the NiP plated substrate in the respect of mechanical strength.

Especially, in the magnetic recording medium in which a low t.cndot.Br value (where t is a thickness of the magnetic layer, and Br is a magnitude of residual magnetization) is required to be used together with the MR head, it causes a serious problem that the magnetic grain is wasted to form silicon compounds since an amount of the magnetic grain in the magnetic film is absolutely small.

On the other hand, when the magnetic recording medium is formed of a plurality of different material layers and thereafter it is heated, there may be a risk of causing a separation of the layers due to difference between coefficients of thermal expansion of the layers.

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