JPS62129934A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled medium having good magnetic characteristics such as coercive force and squareness ratio by interposing Ni in a Cr layer constituted as an underlying film of a magnetic film. CONSTITUTION:A chip of pure Ni is placed on a target plate of pure Cr and is sputtered under the conditions of about 40mTorr gaseous argon pressure and about 100 deg.C substrate temp. to form the Cr layer which is the magnetic underlying film contg. about 2-8wt% Ni to about 4,000Angstrom thickness on the prescribed nonmagnetic substrate. The magnetic film of Co-Ni-Cr is epitaxially grown on such magnetic underlying film to form the magnetic metallic film having about 800Angstrom thickness, by which the magnetic recording medium is obtd. Since Ni is interposed in the Cr layer in the above-mentioned manner, the mag netic characteristics such as coercive force Hc and squareness ratio Rs, S* are improved. The recording medium with which the increase of the reproduc tion output at the improvement of the recording density can be expected is thus obtd. without substantial alteration of the conventional production process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media such as magnetic tapes and magnetic disks.

[Prior art and its problems]

Conventionally, from the viewpoint of high-density recording, for example, a Cr underlayer is provided on a nonmagnetic substrate, and this Cr underlayer and Co-Ni-
A metal thin film type magnetic recording medium provided with a metal magnetic film such as Cr or Co--Ni has been proposed.

In order to further increase the density of such magnetic recording media, research is being conducted to increase the coercive force 11c.

As a result of these studies, as a means to increase the coercive force Hc, for example, forming a metal magnetic film using a vapor deposition method, forming a multilayer film, or introducing oxygen gas when forming a metal magnetic film by vapor deposition. Measures have been proposed.

However, these proposals do not result in a fully satisfactory magnetic recording medium; for example, the vapor deposition method has the disadvantage of extremely poor productivity, and the multilayer film method requires extremely troublesome processes and production It has some disadvantages, and
The method of introducing oxygen gas has a drawback in that the coercive force Hc is not significantly improved.

[Disclosure of the invention]

While conducting research on increasing the density of metal thin film type magnetic recording media, the present inventor thought that the characteristics of increasing the density may be greatly influenced by the underlying film of the metal magnetic film.
I have poured all my energy into research in this area.

In other words, research to increase the density of metal thin film type magnetic recording media has so far focused on metal magnetic films, but the present inventor has developed a research method that differs from the current research flow. With this in mind, he focused his research efforts on the structure of the underlying film for metal magnetic films.

As a result of such research, the present inventor discovered that Ni could be added to the Cr layer, which has been proposed as an underlying film for metal magnetic films.
The magnetic recording medium with the intervening CrT film has finer crystal grains (Fig. 1 shows an electron micrograph of the surface of the CrT film containing 2.7% by weight of Ni, and Fig. 2
The figure shows an electron micrograph of the surface of a CrT film that does not contain any Ni. It should be noted that these base films were formed by sputtering under conditions of an argon gas pressure of 40 mTorr. ), but
It was discovered that magnetic properties such as coercive force Hc, squareness ratio Rs, and S* are improved, making it more preferable for high-density recording.

Note that it is desirable that the proportion of Ni added to this CrT film be approximately 2.8% by weight. That is, Ni
If the amount is too small, the white-bead effect on magnetic properties such as coercive force Hc, squareness ratio Rs, and S* due to Ni addition will be correspondingly small, and conversely, if the amount of Ni is too large, ω-like effects such as bed magnetic force Hc will be reduced. This is because their sexuality has decreased.

The thickness of the Ni-containing Cr underlayer is preferably about 500 to 10,000, and the thickness of the metal magnetic film is preferably about 200 to 2,000.

〔Example〕

A pure Ni chip was placed on a pure Cr target plate, sputtered under conditions of an argon gas pressure of about 40 mTorr and a substrate temperature of about 100°C, and a Ni chip was placed on a predetermined non-magnetic substrate.
A CrWj (magnetic base film) containing approximately 2 to 8% by weight of CrWj is formed to a thickness of approximately 4000 mm.

Next, on this magnetic base film, Co-Ni-Cr
The magnetic film is epitaxially grown to form a metal magnetic film with a thickness of about soo A to obtain a magnetic recording medium.

[Comparative example]

A magnetic recording medium is obtained in exactly the same manner as in the previous example except that the pure Ni chip placed on the pure Cr target plate during the formation of the magnetic underlayer is removed.

That is, a magnetic recording medium in which the magnetic underlayer is made of pure Cr is obtained.

〔Characteristic〕

Regarding the magnetic recording medium obtained on each side above, its coercive force Hc
, squareness ratio Rs, and di were measured as shown in the table.

Table As can be seen from this table, the magnetic recording medium containing Ni in the Cr magnetic underlayer has a coercive force HC1 squareness ratio Rs,
Magnetic properties such as S and S are improved, increasing playback output,
This can be expected to improve recording density.

〔effect〕

The magnetic recording medium according to the present invention has carbon as the base film of the magnetic film.
In a magnetic recording medium configured with an r layer, Ni is interposed in the Cr layer, so magnetic properties such as coercive force Hc, squareness ratio Rs, and S* are improved, and reproduction output and recording density are increased. Further, it has the advantage that it can be manufactured without major modification to the conventional manufacturing process of magnetic recording media, and can be provided easily and at low cost.

[Brief explanation of drawings]

FIG. 1 is an electron micrograph of a base film of a magnetic recording medium according to the present invention, and FIG. 2 is an electron micrograph of a base film of a conventional magnetic recording medium.ゝ-2・, I −゛・koT: ”'!, ii ″, j+...μth 2.
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...)" is deleted. (2) Details, page 6, lines 7-10 f41 drawing...
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Claims (1)

[Claims] A magnetic recording medium comprising a Cr layer as a base film of a magnetic film, characterized in that the Cr layer has Ni interposed therein.