JPH06124428A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the coercive force, reproducing outputs and recording density by forming a magnetic film obtained by adding Pd as a fourth element to a CoCrTa alloy film. CONSTITUTION:The magnetic recording medium has a long thin film medium- made of an undercoating film of Cr and a magnetic film of a Co-series allay on a substrate. Pd as a fourth element is added to the CoCrTa alloy film in the magnetic film. The adding amount of Pd is 1-8at.%. Therefore, the coercive force is improved and the reproducing outputs and recording density can be remarkably improved.

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, and more particularly to a longitudinal thin film medium for hard magnetic disks.

[0002]

2. Description of the Related Art As a high density recording medium for a hard magnetic disk, a metal thin film medium by a sputtering method is now predominant instead of a coating medium.

In order to realize high density recording, this thin film medium is required to have high output and high recording density characteristics. In order to improve these characteristics, it is necessary that the coercive force and the squareness of the medium are large and the disk anisotropy in the circumferential direction is large.

Therefore, in order to obtain the above-mentioned good characteristics, NiP / having a texture groove in the disk circumferential direction is used.
A magnetic recording medium in which a Cr film is formed as an underlayer and then a CoNiCr film or CoCrTa film is formed as a magnetic film using an Al substrate has been proposed (Technical Research Report of the Institute of Electronics, Information and Communication Engineers, CPM88-91 and CPM88-). 9
2, 1988).

[0005]

The above-described conventional magnetic recording medium has a good level of coercive force, squareness ratio, and anisotropy in the circumferential direction in the thin film medium manufacturing technique by the sputtering method. Further, it is necessary to improve them in order to realize ultra-high recording density.

Another object of the present invention is to provide a magnetic recording medium in which the coercive force of the medium is particularly improved in order to realize an ultrahigh recording density.

[0007]

A magnetic recording medium according to a first aspect of the present invention is a magnetic recording medium having a longitudinal thin film medium consisting of a Cr undercoat film and a Co-based alloy film magnetic film on a substrate,
The magnetic film is a CoCrTa alloy film containing Pd as a fourth element.
Is added.

The magnetic recording medium of the second invention is the first
The invention is characterized in that the added amount of Pd is 1 at% or more and 8 at% or less.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

Film formation on the magnetic recording medium of this example was carried out by an RF magnetron type sputtering device.

The target is a 99.9% Cr target for the base film and CoCrTa (12a) for the magnetic film.
A composite target in which Pd pellets were placed on a (t% Cr, 2at% Ta) alloy target was used.

The substrate used was a NiP / Al substrate with textured grooves (surface roughness Rmax = 400 angstrom).

First, Table 1 shows the sputtering conditions of this embodiment.

[0014]

[Table 1]

Here, the amount of Pd added in the magnetic film is CoCr.
It was changed depending on the number of Pd pellets placed on the Ta alloy target.

The magnetic characteristics of the CoCrTaPd / Cr media having various Pd compositions thus produced were measured by VSM. The result is shown in FIG. The composition was analyzed by EPMA.

As shown in FIG. 1, the Pd-added medium of the present embodiment (however, the amount of Pd added is 1 at% or more and 8 at% or less).
Indicates that the coercive force is improved as compared with the conventional medium in which Pd is not added.

Next, the recording / reproducing characteristics of this embodiment will be described.

The medium used as a sample had a Pd addition amount of 4 at
%, A conventional medium without Pd addition was also prepared for comparison. These recording / reproducing media are CoCrTaP.
d After forming the film, a carbon film having a thickness of 300 Å was formed as a protective film.

Table 2 shows the evaluation results of the magnetic characteristics, and FIG. 2 shows the evaluation results of the recording / reproducing characteristics.

[0021]

[Table 2]

In Table 2, Hc ₁ represents the coercive force component in the circumferential direction of the magnetic disk, Hc ₂ represents the coercive force component in the radial direction of the magnetic disk, and S represents the squareness ratio.

FIG. 2 shows the dependence of the reproduction output (V) on the recording density (D).

From the above, the medium of the present embodiment has a higher coercive force due to the magnetic characteristics as described above in comparison with the conventional medium.
As a result, it can be seen that the reproducing voltage and recording density are improved in the recording / reproducing characteristics.

[0025]

As described above, in the magnetic recording medium of the present invention, the coercive force is improved as compared with the conventional medium by adding 1 to 8 at% of Pd to the CoCrTa film.
This has the effect of significantly improving the reproduction output and recording density.

[Brief description of drawings]

FIG. 1 is a graph showing a coercive force P of an embodiment of a magnetic recording medium of the present invention.
It is a characteristic view which shows d addition amount dependence.

FIG. 2 is a characteristic diagram showing the reproduction output and recording density dependency of an example of the magnetic recording medium of the present invention and a conventional medium.

[Explanation of symbols]

 1 Medium of this embodiment 2 Conventional medium

Claims (2)

[Claims] 1. A magnetic recording medium having a longitudinal thin film medium composed of an underlayer of Cr and a magnetic film of a Co-based alloy film on a substrate, wherein the magnetic film is a CoCrTa alloy film to which Pd is added as a fourth element. A magnetic recording medium characterized by: 2. The magnetic recording medium according to claim 1, wherein the added amount of Pd is 1 at% or more and 8 at% or less.