Perpendicular magnetic recording medium

Abstract

A perpendicular magnetic recording medium has a substrate, a soft magnetic underlayer formed on the substrate, arrayed soft magnetic dots formed on the soft magnetic underlayer, and a ferromagnetic recording layer formed on the soft magnetic dots and having magnetic anisotropy in a direction perpendicular to a surface of the substrate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-282439, filed Sep. 27, 2002, the entire contents of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a perpendicular magnetic recording medium capable of achieving high-density magnetic recording. [0004] 2. Description of the Related Art [0005] For performing high-density magnetic recording, it is necessary to reduce the size of magnetic domains, each of which is a recording unit of information. In the perpendicular magnetic recording medium that is generally used nowadays, information is recorded in a magnetic thin film containing magnetically disrupted magnetic grains. In order to reduce the size of the magnetic domains and to discriminate boundaries thereof for the high-density magnetic recording, it is necessary to reduce ...

AI Technical Summary

Benefits of technology

[0011] An object of the present invention is to provide a perpendicular magnetic recording medium having a large allowable positional deviation between the write / read head and the recording region in the recording layer and having high reliability.

[0016] In the perpendicular magnetic recording medium according to the first aspect of the present invention, soft magnetic dots are formed on the soft magnetic underlayer, and a ferromagnetic recording layer is formed on the soft magnetic dots. As a result, each of the soft magnetic dots serves to attract the magnetic flux even in the case where the position of the magnetic pole of the head is deviated from the recording region of the ferromagnetic layer, i.e., the region right above the soft magnetic dot. Thus, it is possible to apply a recording magnetic field effectively to the recording region of the ferro-magnetic recording layer right above soft magnetic dot so as to improve recording performance. It should also be noted that, in the medium of the first aspect, the soft magnetic material is patterned in place of patterning the ferromagnetic recording layer, with the result that it is possible to prevent the magnetic characteristics from being deteriorated by processing of the ferromagnetic recording layer. It is also possible to control to lower the flying height of the magnetic head because the ferromagnetic recording layer is not patterned.

[0017] In the perpendicular magnetic recording medium according to the second aspect of the present invention, a ferromagnetic layer is formed on the soft magnetic underlayer, and soft magnetic dots are formed on the ferromagnetic recording layer. As a result, each of the soft magnetic dots serves to attract the magnetic flux even in the case where the position of the magnetic pole of the head is deviated from the recording region of the ferromagnetic recording layer, i.e., the region right below the soft magnetic dot. Thus, it is possible to apply efficiently the recording magnetic field to the recording region of the ferromagnetic recording layer below the soft magnetic dot so as to improve recording performance. It should also be noted that, since the soft magnetic layer is patterned in place the ferromagnetic recording layer in the medium of the second aspect, it is possible to prevent the magnetic characteristics from being deteriorated by processing of the ferromagnetic recording layer.

[0018] In the perpendicular magnetic recording medium according to the third aspect of the present invention, the recording magnetic field can be applied efficiently so as to improve recording performance like the medium according to the second aspect of the present invention. In addition, it is possible to obtain the effect of suppressing fluctuation of magnetization transition extending over a ferromagnetic recording region. Thus, it is possible to achieve high-density magnetic recording with high reliability.

[0019] In the perpendicular magnetic recording medium according to the fourth aspect of the present invention, a ferromagnetic recording layer is formed on a soft magnetic underlayer having projections formed thereon. As a result, each of the projections serves to attract the magnetic flux even in the case where the position of the magnetic pole of the head is deviated from the recording region of the ferromagnetic recording layer. Thus, it is possible to apply efficiently the recording magnetic field to the recording region of the ferromagnetic recording layer right above the projection so as to improve recording performance. It should also be noted that the upper surface of the soft magnetic underlayer is patterned in place of patterning the ferromagnetic recording layer, with the result that it is possible to prevent the magnetic characteristics from being deteriorated by processing of the ferromagnetic recording layer. It is also possible to simplify the processes. Further, it is also possible to control to lower the flying height of the magnetic head because the ferromagnetic recording layer is not patterned.

Problems solved by technology

However, the problem of the thermal fluctuation inhibits the improvement in the recording density of the perpendicular magnetic recording medium.

As a result, it becomes problematic that the magnetic characteristics of the ferromagnetic recording layer are damaged; in particular, the magnitude and the direction of the perpendicular magnetic anisotropy are deteriorated.

However, it is difficult to lower the flying height in the patterned media, which has been irregularly processed, unlike the ordinary medium having a substantially flat surface.

However, it is difficult to locate the magnetic head accurately at the position of the individual ferromagnetic dot.

Where the position of the magnetic pole of the write head deviates greatly from the ferromagnetic dot, though a slight positional deviation is allowable, it is impossible to apply a recording magnetic field to a part of the ferromagnetic dot, with the result that effective recording magnetic field strength is lowered so as to render the recording efficiency poor.

Therefore, an appreciably large deviation between the magnetic head and the ferromagnetic dot is not allowable.

As described above, the problem that processing deteriorates the magnetic characteristics of the ferromagnetic recording layer was inherent in the conventional patterned media.

Also, the conventional patterned media was defective in that it was difficult to lower the flying height of the magnetic head, and that the allowable positional deviation between the write / read head and the ferromagnetic dot of the recording layer is small.

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