JPS615421A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a satisfactory S/N with a ring type by regulating the coercive force in the facial and vertical directions respectively to H1 and H2, and using a ferromagnetic metallic thin film, wherein H2>=H1 and the vertical anisotropy constant is negative, as a magnetic recording layer. CONSTITUTION:A ferromagnetic metallic thin film 8 is used as a magnetic recording layer in a magnetic recording medium. In the magnetic recording medium, when the coercive force in the facial and vertical directions is designated as H1 and H2, H2>=H1 and the vertical anisotropy constant is negative. Namely, Co-Os is obliquely vapor-deposited on polyethylene terephthalate having 12mum thickness while keeping the terephthalate along a cylindrical can having 60cm diameter, the minimum incident angle is changed from 30 deg. to 50 deg., and the surface temp. of the can is selected in the temp. range -40-+60 deg.C to form a thin film having different H1 and H2. Then the magnetic characteristics of the obtained thin film are measured, and a satisfactory S/N is obtained, when the recording and reproduction are carried out with an Mn-Zn ferrite head.

Description

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

In recent years, magnetic recording media in which the magnetic recording layer is a so-called perpendicular magnetization film that can be magnetized in the perpendicular direction of the substrate have attracted attention as a medium with excellent short wavelength recording characteristics.

The most promising technology in terms of recording density is the □ auxiliary magnetic pole excitation type perpendicular head and the so-called two-layer laminated structure of a soft magnetic layer typified by permalloy and a perpendicular magnetization film typified by a Go-Or sputtered film. Although it is considered to be a combination of media, the ring-type helad has excellent practical reliability and has the highest recording density at present, resulting in a more favorable signal-to-noise ratio (
With perpendicular media, it became clear that it was impossible to obtain E/N), and progress was made in the development of magnetic heads in which the auxiliary magnetic pole and the main magnetic pole were arranged on the same side of the magnetic recording medium instead of being arranged to sandwich the magnetic recording medium. However, sufficient S/N is ensured.
'a・zu・°°−°”11−・30°”1・
Even if 1Go-cr is lined with permalloy, it will cost 40
(!Since only the values before and after 1 are obtained, improvement is desired.

OBJECTS OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-density magnetic recording medium that can obtain a sufficient S/N using a ring-type head. The magnetic recording medium is characterized by a negative perpendicular anisotropy constant and a negative perpendicular anisotropy constant, where the coercive forces in the in-plane direction and perpendicular direction are H, H2, respectively. This can be achieved with good S/N.

Description of examples The present invention will be described in detail below with reference to the drawings.

FIG. 1 is an example of a conventional perpendicular recording medium.

In Figure 1, 1 is a non-magnetic substrate such as a polymer, 2 is a soft magnetic layer, 3 is a perpendicularly magnetized film, 4 is a main magnetic pole, 5 is an auxiliary magnetic pole, and 6
is an excitation coil, and the arrows schematically indicate the paths of magnetic flux.

The effects of the present invention will be clarified by comparing the recording and reproducing capabilities achieved in this system with the present invention.

FIG. 2 is a schematic diagram of the magnetic recording system of the present invention. In FIG. ≧H1 and the perpendicular anisotropy constant is negative. 10ii ring head.

The magnetic recording medium of the present invention can be provided with a protective film, a back coat layer, an underlayer, etc. as necessary, and may be used in the form of either a magnetic tape or a magnetic disk.

Comparing the magnetic recording medium of the present invention with either conventional longitudinal recording or perpendicular recording, they are not the same. This is because perpendicular recording requires that the anisotropy constant be positive, which is longitudinal recording fiH,)H2.

As is clear from the specific comparison described below, the reason why sufficient S/N can be obtained by recording and reproducing using a ring head for high-density recording is that the magnetization efficiency is high, especially the magnetic field created by the narrow gap is This is considered to be because the best conditions can be satisfied in relation to the dimensions of the ferromagnetic thin film.

Nonmagnetic substrates that can be used in the present invention include polymer films such as polyesters, polyolefins, polyamides, and polyimides, and nonmagnetic plates such as aluminum alloys.

The magnetic recording layer used in the present invention is Go, Go-Fe
.

Go-Ni, Go-Or + Go-V, Co
-Ti, Go-Mo.

Co-W, Co-Ni-P, Co-Mn-P
, Go-! '? Any of u-P, etc. 11 may be used, as long as the coercive force and the perpendicular anisotropy constant satisfy the above-mentioned conditions.

An example will be described in more detail below.

〔Example〕

6 diameter on polyethylene terephthalate with a thickness of 12 μm
Oo-Os was obliquely deposited along the cylindrical can of ocrn. The minimum incident angle was varied from 30° to 50' and the surface temperature of the can was selected from -40°C to +6°C to form different thin films of MiH2 and H2.

In addition to measuring the magnetic properties of the obtained thin film, the gear knob 0
．． Recording and reproduction were performed using an 18 μm Mn-Zn ferrite head, and the S/N was measured.

For comparison, Ni was deposited on the same film using a sputtering method.
-Fe film (Nisowt%) 0.5 μm, Go
A perpendicular medium on which a -Cr (20 wt %) film was formed to a thickness of 0.15 μm and a Go-B amorphous alloy as a main magnetic pole (the width of the magnetic pole was 0.18 μm) were used for recording and reproduction using a vertical head. The results are shown in the table below.

As is clear from the table, the product of the present invention has an excellent S/N ratio in high-density recording.

Also, since it can be a single layer, it is easy to manufacture the media.
It is noteworthy that a ring head also provides improved S/N than the vertical head, dual layer media combination.

In the present invention, it has been confirmed that almost the same S/N can be achieved even with combinations of the other materials mentioned above.

Effects of the Invention The magnetic recording medium of the present invention has a magnetic recording layer made of a ferromagnetic metal thin film whose perpendicular coercive force is equal to or greater than the in-plane coercive force and whose perpendicular anisotropy constant is negative. It is capable of obtaining a sufficient S/N ratio through high-density recording and reproduction, and has great practicality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing conventional perpendicular recording, and FIG. 2 is a diagram for explaining the magnetic recording medium of the present invention. 9...Ferromagnetic metal thin film, 1o...Ring head. Name of agent: Patent attorney Kazuo Nakao and 1 other person 2nd
figure

Claims (1)

[Claims] A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film having a negative perpendicular anisotropy constant and H_2≧H_1, where the coercive forces in the in-plane direction and the perpendicular direction are H_1 and H_2, respectively.