JPS6174134A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a vertical magnetic recording medium having excellent S/N particularly for high-density recording and reproduction by forming a magnetic layer into the two-layered constitution in which a Co-O or Co-Ni-O film is disposed on a soft magnetic layer and providing the magnetic layer having no inter-diffusion between the layers. CONSTITUTION:The soft magnetic layer 6 consisting of 'Permalloy(R)', etc. is formed on a substrate 5 consisting of polyester, cellulose deriv., etc. and is subjected to a glow discharge treatment in gaseous O2 of 1X10<-2>Torr. The Co-O film or Co-Ni-O film 7 is then formed at <=10 deg.C substrate 5 temp. The magnetic layer of the two-layered constitution which obviates the generation of the inter-diffusion in the boundary 8 of the films 6, 7 is thus provided by using the Co-O or Co-Ni-O which permits the formation of the vertically magnet izable film at the low temp. The vertical magnetic recording medium which eliminates the uneven sensitivity owing to the nonuniformity in the diffusion phenomenon, eliminates the source for noise and has the excellent S/N is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a perpendicular magnetic recording medium suitable for high-density magnetic recording and reproduction.

Conventional Structures and Their Problems In recent years, efforts have been made to put into practical use magnetic recording media in which a magnetic recording layer is a ferromagnetic metal thin film in order to meet the demand for higher density magnetic recording. This type of media can be roughly divided into longitudinal recording, which has been widely used in practice, and so-called perpendicular recording, which is magnetized perpendicularly and antiparallel to the film surface, which improves demagnetization loss in short wavelength recording when longitudinal recording is used. It is divided into magnetic recording.

In particular, perpendicular magnetic recording is attracting attention as it is expected to rival optical recording as a high-density recording.

FIG. 1 is an enlarged sectional view of a conventional laminated type magnetic recording medium for perpendicular magnetic recording.

In FIG. 1, 1 is a polymer substrate, 2 is a soft magnetic layer such as permalloy, 3 is a nonmagnetic layer such as Ti, and 4 is a perpendicular magnetic layer such as Co--Cr.

By using a medium with this configuration and recording and reproducing short wavelengths using an auxiliary magnetic pole excitation type vertical head, it is thought that a recording wavelength of 0.3 μm will be sufficiently practical, and the frequency characteristics are certainly good. In reality, the signal-to-noise ratio (
S/N ratio) is still insufficient.

The cause of this is not well known, but it changes slightly depending on the lamination conditions, so it is due to mutual diffusion of permalloy and, for example, T1, or -C when there is no Ti.

It is inferred that mutual diffusion of -Cr and permalloy is involved.

This fact can be known analytically, and interdiffusion is unavoidable due to manufacturing process conditions, whether by high-frequency sputtering or vacuum evaporation on a substrate kept at high temperature.

It is thought that the non-uniformity of this diffusion phenomenon becomes a source of uneven sensitivity and noise, resulting in a decrease in the S/N ratio, and therefore improvements are desired.

Purpose of the Invention The present invention has been made in view of the above circumstances, and is an improved S
The magnetic recording medium of the present invention provides a perpendicular magnetic recording medium having a /N ratio of Co-0 or Co-0 on a soft magnetic layer.
A particularly short wavelength device characterized by stacking perpendicularly magnetized films of -Ni-◯ without mutual diffusion.

The S/N ratio is good when the track narrows.0 Description of examples Examples of the present invention will be described in detail below.

FIG. 2 is an enlarged sectional view of the magnetic recording medium of the present invention.

In Figure 2, 6 is a polymer substrate, 6 is a soft magnetic layer, and 7 is C
A perpendicular magnetization film consisting of an o-0 film or a Co-Ni-0 film,
It is constructed under the condition that there is no mutual diffusion at the interface 8 between the membrane 6 and the membrane 7.

Polymer substrates that can be used in the present invention include polyesters such as polyethylene terephthalate and polytetramethyleneterephthalate, cellulose derivatives such as cellulose triacetate and nitrocellulose, polyamide, polyamideimide, and polyimide.

The soft magnetic layer that can be used in the present invention may be any layer as long as it has low coercive force and high magnetic permeability.
Permalloy is currently superior.

Co -0 and Co -N i-0 used in the present invention are:
Any material that satisfies the conditions for a perpendicularly magnetized film may be used, and a vacuum evaporation method is suitable as a manufacturing method.

In other words, in order to prevent mutual diffusion, it is preferable that the temperature of the interface is close to each other during manufacturing as well as the material composition, and C0-Cr, C
o-V, Co-Ti, Co-Mo,
Well-known perpendicular magnetization films such as Co-W and Co-RuCo-Ni-P cannot be used because they do not become perpendicular magnetization films unless the temperature at the interface becomes high.

Conversely, Co-0, or Co -N i -0, @10℃
A perpendicularly magnetized film can be obtained even with the following, and as will be described later, after forming the Ni-Fe film and performing oxygen glow treatment for a short time, Co-0 or Co-N i -
Mutual diffusion can be sufficiently prevented by forming the zero film at a temperature of 10° C. or lower.

It goes without saying that the medium of the present invention may be provided with a protective layer for lubrication on its surface, a magnetic recording layer may be provided on both sides of a polymer substrate, or may be used in either disk or tape form. It is.

One embodiment will be described in more detail below.

(Example) An 8% Ni-20F film was deposited on a 12 μm thick polyethylene terephthalate film by high frequency sputtering.
A 0.5 μm permalloy thin film was formed using e as a target, and then glow discharge treatment was performed in oxygen at 1×1σ2 Torr.

While moving the polyethylene terephthalate film on which the permalloy thin film was formed along a cylindrical can with a diameter of 5ocWL, only the near-vertical component within the incident angle of 10 degrees was detected.
15 wt%) was electron beam evaporated.

Adjust the surface temperature and oxygen partial pressure of the cylindrical can to reduce the thickness to 0.
A perpendicular magnetization film of 15 μm was formed.

As comparative examples, we prepared a Permalloy thin film in which a Co-0 film was formed without glow discharge treatment, and a Co-Cr film in which a Co-Cr film was formed by high-frequency sputtering.

Each was used as a magnetic disk, and an auxiliary magnetic pole excitation type perpendicular head having a 0.2 μm thick amorphous alloy as the main magnetic pole was used to perform recording and reproduction at a recording wavelength of 0.3 μm, and relative comparisons were made in S/N. The presence or absence of mutual diffusion was investigated by Auger electron spectroscopy. The manufacturing conditions and measurement results are summarized in the table.0 As described above, the product of the present invention has an S/N improvement of 2 to 3 dB.

In addition to this example, other combinations of the above-mentioned materials may also be used.
It was possible to confirm that the S/N ratio was improved to the same degree.

Effects of the Invention As described above, the magnetic recording medium of the present invention has an S /N has been improved, and its practicality is 0.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a conventional magnetic recording medium for perpendicular magnetic recording, and FIG. 2 is an enlarged sectional view of a magnetic recording medium of the present invention. 5...Polymer substrate, 6...Soft magnetic layer,
7... Perpendicular magnetization film (Co-0, or Co-N
i-0).

Claims (1)

[Claims] 2 with Co-O or Co-Ni-O film arranged on the soft magnetic layer
A magnetic recording medium characterized by a layered structure in which there is no mutual diffusion between layers.