JP2725502B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a hard magnetic disk.

[0002]

2. Description of the Related Art In magnetic recording technology, a perpendicular magnetic recording system has been proposed as a high-density recording technology capable of achieving a higher density than a longitudinal magnetic recording system currently in practical use, and research and development have been actively pursued. I have. This recording medium includes CoC having magnetic anisotropy in a direction perpendicular to the film surface.
Magnetic films such as r and CoCrTa alloys are used and formed by sputtering or vapor deposition (Journal of the Japan Society of Applied Magnetics, Vol. 8, No. 1, 1984, 17p). Here, in order to obtain characteristics of high output and high recording density, it is necessary to have high perpendicular magnetic anisotropy in the magnetic characteristics of the medium and to increase the coercive force in the perpendicular direction as much as possible.

[0003]

However, when the coercive force in the vertical direction is almost uniform in the film thickness direction as in the conventional magnetic recording medium, the recording magnetic field of the head becomes lower in the lower layer of the magnetic recording medium. I can't record enough. Therefore, it is necessary to lower the coercive force of the lower layer of the magnetic recording medium in order to improve the reproduction output and the recording density. The purpose of the present invention is
It is an object of the present invention to provide a magnetic recording medium having improved reproduction output and recording density by making the lower layer of the magnetic recording medium have a low coercive force.

[0004]

According to the present invention, there is provided a magnetic recording medium wherein a recording layer formed on a substrate comprises a magnetic layer having a low coercive force and a perpendicular magnetization film having a high coercive force. A magnetic recording medium characterized in that the CoCrTa alloy film contains Mo as a fourth element.

[0005]

The CoCrTa film has a hexagonal close-packed structure, and the c-axis is well oriented in the direction perpendicular to the film surface, so that the perpendicular anisotropy magnetic field and the perpendicular coercive force are high. , A low coercive force layer can be obtained.

[0006]

Embodiments of the present invention will be described below.
FIG. 1 is a cross-sectional view of an example of a magnetic recording medium according to the present invention, in which a CoCrTa + Mo alloy film 2 and a CoCr
Ta alloy films 3 are sequentially formed. In this embodiment, RF
The above magnetic recording medium was manufactured using a magnetron type sputtering apparatus. Target is 8 for low coercivity layer
A composite target combining an 0Co-17Cr-3Ta (at%) alloy and a Mo chip, an 80Co-17Cr-3Ta (at%) alloy target for a high coercive force perpendicular magnetic film, and a car target for a protective film. Bond targets were used. The substrate used was a NiP / Al substrate. Table 1 shows details of the film forming conditions.

[0007]

[Table 1]

First, the amount of Mo added is changed depending on the number of Mo chips placed on the CoCrTa alloy target, and various CoCrTa + Mo films (500 Å) are formed.
Was formed, and magnetic characteristics were measured using VSM. FIG.
FIG. 9 shows the change in coercive force with respect to the amount of Mo added. In addition,
Composition analysis was performed using EPMA. FIG. 2 shows that the coercive force becomes low when the amount of Mo added is 3.5 at% or more.

Next, the recording / reproducing characteristics of the medium of the present invention will be described. Here, a low coercivity layer (500 Å
A CoCrTaMo film doped with 4 at% of Mo was used as a film, CoCrTa (1500 Å) was formed on this low coercivity layer, and finally a C protective film (300 Å) was formed. Produced. Furthermore, for comparison, CoCrT without the low coercivity layer was used on the same substrate.
A conventional medium having only the a alloy film (2000 Å) was also manufactured. Table 2 shows the results of examining the magnetic properties of the medium thus formed.

[0010]

[Table 2]

Next, FIG. 3 shows the result of comparing the R / W characteristics of the medium A of the present invention and the conventional medium B with a thin-film magnetic head. This indicates that the medium of the present invention has improved reproduction output and recording density as compared with the conventional medium. In this embodiment, CoCrTa is used as the high coercive force layer, but another element may be added to this layer, or CoNi, CoCrW, or the like may be used.

[0012]

According to the present invention, the lower layer portion of the medium has a low coercive force, and the reproduction output, the recording density and the like are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention.

FIG. 2 shows the CoC of the coercive force (Hc) in the vertical direction in the magnetic characteristics.
FIG. 4 is a diagram showing the dependency of the amount of Mo added to the rTa film.

FIG. 3 is a diagram showing the recording density characteristics of the medium of the present invention in comparison with a conventional medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 CoCrTa + Mo alloy film 3 CoCrTa alloy film

Claims (1)

(57) [Claims] 1. A magnetic recording medium in which a recording layer formed on a substrate comprises a low coercivity magnetic layer and a high coercivity perpendicular magnetization film, wherein the low coercivity magnetic layer is formed on the CoCrTa alloy film as a fourth element. A magnetic recording medium comprising Mo.