JPH05159264A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain characteristics of a high output and high density by forming a low-coercive force layer constituted by adding Zr to CoCrTa on a substrate, then forming a perpendicularly magnetized layer having high coercive force and consisting of a CoCrTa alloy film thereon. CONSTITUTION:The low-coercive force layer 2 is provided on the NiP/Al substrate 1 by using a sputtering device of an RF magnetron system and a composite target formed by combining an 80Co-17Cr-3Ta alloy and a Zr chip. In succession, the perpendicularly magnetized film 3 is formed by the 80Co-17Cr-3Ta alloy target. The reproduced output and the recording density, etc., are improved by providing the low-coercive force layer 2 in the lower layer part of the medium in such a manner.

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, and more particularly to a perpendicular magnetic recording medium for ultra high recording density recording.

[0002]

2. Description of the Related Art Research and development are being vigorously pursued for practical application of perpendicular magnetic recording, which is expected to have a next-generation ultra-high recording density. That is, in the perpendicular recording method, as the recording signal has a shorter wavelength, that is, the recording density increases,
Since the demagnetizing field is small and the recording magnetization is stable, it is advantageous for high-density recording over the longitudinal recording method.

The recording medium is CoCr and CoCrT formed by sputtering or vapor deposition.
A magnetic film such as a-alloy has been proposed as an extremely excellent one (Journal of Japan Applied Magnetics, Vol. 8, No. 1,
1984, 17p). Here, in order to obtain the characteristics of high output and high recording density, it is necessary to increase the perpendicular magnetic anisotropy and also increase the coercive force in the perpendicular direction as much as possible.

[0004]

Conventionally, the coercive force in the perpendicular direction of a magnetic recording medium is almost uniform in the film thickness direction, whereas the strength of the recording magnetic field generated from the magnetic head is different from that of the magnetic recording medium. The thickness decreases from the surface in the depth direction. Therefore, the recording magnetic field becomes low in the lower layer portion of the magnetic recording medium, so that sufficient recording cannot be performed. 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 recording density.

An object of the present invention is to provide a magnetic recording medium in which the lower layer portion of the magnetic recording medium has a low coercive force.

[0006]

The present invention provides a magnetic recording medium having a low coercive force magnetic layer and a high coercive force perpendicularly magnetized film on a substrate, wherein the low coercive force layer is a CoCrTa alloy film and a fourth element. Is included as Zr.

[0007]

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 become large. By containing Zr, a low coercive force layer can be obtained.

[0008]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a sectional view of an embodiment of the magnetic recording medium of the present invention.

An RF magnetron type sputtering apparatus was used for manufacturing this embodiment. In addition, the substrate 1 is NiP / Al
A substrate was used. Target is 80C for low coercive force layer
O-17Cr-3Ta (at%) alloy and Zr tip combined target, 80C for perpendicular magnetization film
An o-17Cr-3Ta (at%) alloy target and a carbon target for the protective film were used, respectively.
Table 1 shows the details of the film forming conditions.

[0011]

[Table 1]

First, various CoCrTaZr alloy films 2 (700 angstroms) were formed by changing the number of Zr chips placed on the CoCrTa alloy target and changing the added amount of Zr.

FIG. 2 shows the change in coercive force with respect to the added amount of Zr. In addition, the composition was analyzed by EPMA, and VSM
Magnetic properties were measured by. As a result, it was found from FIG. 2 that a low coercive force was obtained when the Zr addition amount was 3.0 at% or more.

Next, the recording / reproducing characteristics of the magnetic recording medium of the present invention will be described. Here, as a low coercive force layer (700 angstrom), CoCrTaZ with Zr4at% added
The r film 2 is used, and C is formed on this low coercive force layer as a high coercive force layer.
An oCrTa alloy film 3 (1,300 angstrom) was formed, and finally carbon (300 angstrom) was formed as a protective film. For comparison, a conventional magnetic recording medium having only a CoCrTa alloy film (2,000 angstrom) without a low coercive force layer was prepared on the same substrate.

[0015]

[Table 2]

FIG. 3 shows the magnetic recording medium A of the present invention and the conventional magnetic recording medium B which were read by the thin-film magnetic head as R /
The result of having compared W characteristics is shown. From this, it was found that the magnetic recording medium of the present invention has improved reproduction output and recording density as compared with the conventional magnetic recording medium.

[0017]

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

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording medium of the present invention.

FIG. 2 is a diagram showing the dependency of coercive force (Hc) on the CorTa film in terms of magnetic characteristics, in the amount of Zr added.

FIG. 3 is a diagram comparing recording density characteristics of a magnetic recording medium of the present invention with a conventional magnetic recording medium.

[Explanation of symbols]

 1 Substrate 2 CoCrTa + Zr alloy film 3 CoCrTa alloy film

Claims (1)

[Claims] 1. A magnetic recording medium having a low coercive force magnetic layer and a high coercive force perpendicularly magnetized film on a substrate, wherein the low coercive force layer contains Zr as a fourth element in a CoCrTa alloy film. Magnetic recording medium.