JPH04704A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium whose C/N ratio is high even at a high density by a method wherein the substratum of a magnetic layer is formed of an alloy containing a specific amount or higher of Cr, a layer composed of a specific alloy is formed on a support substrate and a magnetic layer composed of a Cr-based magnetic alloy is formed on it. CONSTITUTION:A substratum is formed of at least one or more kinds of alloys which contain 30wt.% or higher of Cr and which are selected from IrCR, OsCr, BiCr, WCr, RuCr, MoCr, BeCr and RhCr. A magnetic recording medium is provided with the following: a subtsratum 1 formed on a support substrate composed of a high-polymer film; a magnetic layer 2 formed on the substratum 1; and a protective film 3 with which the magnetic layer is covered. The substratum 1 is formed of a Cr alloy with Mo or W. The magnetic layer is formed of a CoCr alloy. The protective film 3 is formed of C. At an initial orientation layer 4 of the magnetic layer 2 composed of the CoCr alloy, the disorder of an initial orientation at the magnetic layer composed of the CoCr alloy is reduced because the substratum layer contains a Cr composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a magnetic recording medium, and more particularly to a perpendicular magnetic recording medium.

[Prior Art] In recent years, with the demand for higher density magnetic recording, research has been actively conducted on perpendicular magnetic recording methods, which are less affected by demagnetizing fields and are expected to dramatically improve recording density.

As a specific application of this perpendicular magnetic recording method.

There is recording and playback of high-definition video, such as high-definition. Recording such high-quality video requires a large amount of recording capacity, and magnetic tape using the conventional longitudinal recording method can only record for a short time. For this reason, the practical application of perpendicular magnetic recording media capable of high-density recording is awaited.

On the other hand, recently there is a still video system (hereinafter abbreviated as S) that can record still images on a 2' floppy disk and reproduce them on a television monitor. Traditionally, 2' floppy disks with a longitudinal recording system have been commercially available, but they have not yet achieved a resolution that is satisfactory for still images compared to silver halide photography, and here too, higher quality images can be obtained. Therefore, there is a need for a perpendicular magnetic recording medium that can be expected to dramatically improve recording density. Therefore, the magnetic layer is formed only of magnetic material. A so-called serial control thin film type perpendicular magnetic recording medium is being studied especially in this SV system.

Such perpendicular magnetic recording media have a magnetic layer of 0.2 to 0.3
Because it is thin and microscopic, it was not possible to achieve passware durability of more than 2 million passes, which is required for the Sv system.

For this reason, research is being carried out on methods of increasing the strength of perpendicular magnetic recording media and improving the password durability by providing a nonmagnetic underlayer under the magnetic layer.

In addition, as a magnetic layer for perpendicular magnetic recording media.

CoCr alloys and other Cr-based alloys are known.

FIG. 4 is a sectional view showing a conventional perpendicular magnetic recording medium.

In FIG. 4, the perpendicular recording medium has a magnetic layer 52 made of a CoCr alloy for perpendicular magnetic recording formed on a base layer 51 by sputtering or the like, and a protective film 53 provided thereon.

The portion of the magnetic layer facing the underlayer 51 is called an initial orientation layer 54. The nonmagnetic underlayer 51 is made of Ir.

Os, Bi, W, Ru, Mo, Be, and Rh are used, and good durability is obtained.

[Problems to be Solved by the Invention] However, in the magnetic recording medium using the underlayer 51 described above, a thick layer 54 called an initial orientation layer with disordered orientation is formed in the portion of the CoCr magnetic layer 52 that is in contact with the underlayer 51. is formed. Therefore, C.

There is a drawback that the perpendicularly oriented region of the Cr magnetic layer 52 becomes thinner.

As shown in FIG. 5, the conventional magnetic recording medium with an underlayer has a lower reproduction output in high-density recording than a magnetic recording medium without an underlayer, which detracts from the advantages of the perpendicular magnetic recording system.

In order to perform the high-density recording required for the S system for high image quality, the C/N must be 50 dB or more at 100 kFRPI, but in a perpendicular magnetic recording medium using the underlayer 51, such a high C/N is not possible. was not obtained.

Therefore, one technical object of the present invention is to provide a magnetic recording medium with a high C/N ratio even at high density.

[Means to solve the problem] The present invention aims to solve such technical problems.

The underlayer of the magnetic layer is an alloy containing 30 νt% or more of C, including IrCr, 0sCr, B1Cr, and WCr.

A layer made of an alloy of at least one of RuCr, MoCr, BeCr, and RhCr is provided on a support substrate, and a magnetic layer made of a Cr-based magnetic alloy is formed on the layer. The present invention provides a perpendicular magnetic recording medium with high perpendicular magnetic recording speed.

In the present invention, the Cr content of the Cr alloy of the underlayer is limited to 30% or more because the C/N ratio is clearly improved in a Cr alloy with Or of 30% or more.

Further, in the present invention, the Cr-based magnetic alloy constituting the magnetic layer can be CoCr alloy, CoCrTa alloy, etc., but is not limited to these as long as it is a magnetic alloy containing Cr.

[Function] In the present invention, since the base layer contains a Cr component, Cr
Disturbances in the initial orientation of the magnetic layer made of the system magnetic alloy are reduced, and a high C/N ratio can be obtained even at high recording densities.

[Example] Examples of the present invention will be described below.

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

In FIG. 1, a magnetic recording medium includes a base layer 1 formed on a support substrate made of a polymer film (not shown), a magnetic layer 2 formed on this base layer 1, and a protective film 3 covering this magnetic layer. It is equipped with

The base layer 1 is made of a Mo or W Cr alloy.

The magnetic layer is a CoCr alloy (Cr17vt%, C.

remainder).

Further, the protective film 3 is made of C.

In the initial orientation layer 4 of the magnetic layer 2 made of a CoCr alloy, since the underlayer contains a Cr component, the initial orientation of the magnetic layer 4 made of a Co-Cr alloy is less disturbed.

A magnetic recording medium according to an example of the present invention was manufactured as follows.

(Example 1) A polyimide film with a thickness of 30 μm was used as a supporting substrate, and on this a MoCr (10 vt% Cr, remainder of Mo) film with a thickness of 0.3 μm was formed as an underlayer 1 by magnetron sputtering, and a 0.3 μm thick MoCr (10 vt% Cr, remainder of Mo) film was formed as a magnetic layer 2. CoCr (C
r 17vt%, Co balance) membrane.

As the protective film 3, 200 C films were successively formed.

(Example 2) In Example 1, the composition of the Mo Cr alloy of the underlayer 1 was 20 vt% Cr and the remainder Mo. A magnetic recording medium was manufactured in the same manner as in Example 1 in other respects.

(Example 3) In Example 1, the composition of the Mo Cr alloy was set to 30 sit% of C and the remainder of Mo.A magnetic recording medium was produced in the same manner as in Example 1 except for the following.

(Example 4) In Example 1, the composition of the Mo Cr alloy was changed to Cr50v.
t%, Mo remainder. A magnetic recording medium was produced in the same manner as in Example 1 in other respects.

(Example 5) In Example 1, the composition of the Mo Cr alloy was changed to Cr70v.
t%, Mo remainder. A magnetic recording medium was produced in the same manner as in Example 1 in other respects.

(Example 6) In Example 1, the composition of the Mo Cr alloy was changed to Cr90v.
t%, Mo remainder. A magnetic recording medium was produced in the same manner as in Example 1 in other respects.

(Example 7) A magnetic recording medium was produced in the same manner as in Example 3, except that an IrCr alloy was used instead of Mo Cr as the underlayer 1 in Example 3.

(Example 8) A magnetic recording medium was produced in the same manner as in Example 3, except that 0sCr was used instead of the Mo Cr alloy as the underlayer 1 in Example 3.

(Example 9) A magnetic recording medium was produced in the same manner as in Example 3 except that a B1Cr alloy was used instead of the MoCr alloy as the underlayer 1 in Example 3.

(Example 10) A magnetic recording medium was produced in the same manner as in Example 3 except that a WCr alloy was used instead of the MoCr alloy as the underlayer 1 in Example 3.

(Example 11) A magnetic recording medium was produced in the same manner as in Example 3, except that a RuCr alloy was used as the underlayer 1 instead of MoCrh gold.

(Example 12) A magnetic recording medium was produced in the same manner as in Example 3, except that Beer alloy was used instead of Mo Cr alloy as the underlayer 1 in Example 3.

(Example 13) A magnetic recording medium was produced in the same manner as in Example 3 except that a RhCr alloy was used instead of the Mo Cr alloy as the underlayer 1 in Example 3.

(Comparative Example) For comparison, a conventional continuous magnetic recording medium shown in FIG. 4 was manufactured.

A base layer 51 with a thickness of 0 is formed by magnetron sputtering on a polyimide film with a thickness of 30 μm as a support substrate.
．． 2μm CoCr (Cr 17wt%, remaining Co)
A film was formed, and a 200-layer C film was formed thereon as a protective film 53.

FIG. 2 shows the relationship between the Cr content (wt%) and C/N of the magnetic recording media produced in Examples 1 to 6 and Comparative Example. This relationship is the result of testing at a recording density of 100 kFRPI using a commercially available SV recording/reproducing machine. Second
From the figure, it was found that an output of 50 dB or more can be obtained when Cr is 30 wt% or more.

100kFR of media made by Examples 7-13
Figure 3 shows the C/N at PI.

As shown in Figure 3, any magnetic recording medium has a
An output of more than dB was obtained.

[Effects of the invention] As described above, according to the present invention, the C/N can be reduced even at high density.
It is possible to provide a perpendicular magnetic recording medium with high perpendicular magnetic recording speed.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of a cross-sectional structure of a perpendicular magnetic recording medium according to the present invention, and FIG. 2 is a diagram schematically showing an example of a cross-sectional structure of a perpendicular magnetic recording medium in the present invention.
This is a diagram showing the relationship between Cr concentration and C/H in a Cr layer. For comparison, a Co-Cr layer with a thickness of 0.2411 without an underlayer is
(Cr 17wt%, remaining Co) The C/N of the film formed thereon is also shown. 3 is a diagram showing the measurement results of C/N of the magnetic recording media manufactured in Examples 7 to 14, FIG. 4 is a diagram schematically showing an example of the cross-sectional structure of a conventional perpendicular magnetic recording medium, and FIG. FIG. 5 shows recording density characteristics of a conventional medium provided with an underlayer and a perpendicular magnetic recording medium without an underlayer. In the figure, 1... Underlayer, 2... Magnetic layer, 3... Protective film. 4... Initial orientation layer, 51... Base layer, 52... Magnetic layer. 53... Protective film, 54... Initial alignment layer. Fig. 2 8° [wt%] CrJi degree of underlayer Fig. 4 53 Protective film

Claims (1)

[Claims] 1. In a magnetic recording medium in which a Cr-based magnetic alloy thin film for magnetic recording is formed on an underlayer formed on a support substrate, the underlayer is an alloy containing 30 wt% or more of Cr, IrCr, OsCr, BiCr, WCr, RuCr
, MoCr, BeCr, and RhCr.