JPS60211618A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain an SN ratio which is substantially high even at <=0.5mum recording wavelength with a ring type magnetic head by setting the ratio of the coercive forces in the direction perpendicular to the vertical magnetized film having the axis of easy magnetization in the direction perpendicular to the film plane and within the plane thereof in a prescribed range. CONSTITUTION:The ratio of the coercive force in the perpendicular direction of the vertical magnetized film having the axis of easy magnetization in the direction perpendicular to the film plane with the coercive force in the plane thereof is so set as to be within the range from 1.05 to 1.25. The substantially high SN ratio is thus obtd. even at <=0.5mum recording wavelength with the ring type magnetic head.

Description

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

Conventional Structure and Problems There is a perpendicular recording method as a magnetic recording method with excellent short wavelength recording characteristics. This method requires a perpendicular recording medium whose axis of easy magnetization is perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented perpendicularly to the film surface of the medium, and therefore, the shorter the signal wavelength, the smaller the demagnetizing field within the medium, and the better the reproduced output.

This method includes a type using a ring head and a type using a main magnetic pole and an auxiliary magnetic pole.

At present, the one with the highest sensitivity is the one shown in FIG. 1, which is a sectional view showing an example of the structure of a perpendicular magnetization type magnetic recording medium having a main magnetic pole 1 and an auxiliary magnetic pole 2. In the figure, 3 is an excitation coil of the auxiliary magnetic pole 2. The magnetic recording medium is a three-layer structure in which a soft magnetic layer 6 such as a permalloy film as an auxiliary medium is formed on the surface of a base 6 made of polyester or the like, and a perpendicular magnetization film 4 such as Go-Or or the like is formed thereon as a recording medium. It has a structure. The magnetic flux shown by the broken line is focused by the soft magnetic layer 5, which is an auxiliary medium with high magnetic permeability, and passes through the perpendicular magnetization film 4, which is a recording medium, to the main pole 1 by 1 m.

This method is currently being researched and developed, but in order to perform high-density recording on magnetic tape, it is necessary to obtain a sufficient S/N (signal-to-noise ratio) by recording and reproducing using a proven ring head. preferable.

However, even if the orientation of the C-axis, which is the main axis of a hexagonal close-packed structure such as Go-Or, is improved, the perpendicular coercive force is increased, or the % saturation magnetization is increased, it is not necessary to record and play back videos. Since it is not possible to obtain a S/N of a 5 dB or more, the actual situation is that the advantage of perpendicular recording, in which the root magnetic field of short wavelengths is small, cannot be utilized.

OBJECTS OF THE INVENTION An object of the present invention is to provide a magnetic recording medium that can obtain a sufficiently high S/N ratio even at a recording wavelength of 0.5 μm or less using a ring-type magnetic head.

Structure of the Invention The magnetic recording medium of the present invention has a perpendicularly magnetized film in which the axis of easy magnetization is perpendicular to the film surface, and the ratio Hc/Ha/ of the perpendicular coercive force Hc± to the in-plane coercive force Hc/ is 1. 05 to 1.2
It is characterized by being in the range of 0.5 regardless of magnetic heads such as ring type heads and auxiliary magnetic pole excitation type perpendicular heads.
It is possible to obtain an S/N of 45 dB or more in the recording wavelength range of /lZm or less.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a portion of a hysteresis curve illustrating the present invention. 7 in the figure is a magnetization curve in the vertical direction, 8111 m in-plane direction, and the values indicated by arrows in the figure are the vertical coercive force Ha and the in-plane coercive force Hc/, respectively.

The magnetic recording medium of the present invention was completed by discovering that the value of Hc/Ha/ has an important relationship with short wavelength recording and reproduction, particularly reproduction S/H. As shown in the S/N when reproduced by Rinogen, an S/N of 45 dB or more can be obtained by setting Ha/Hcz in the range of 1.05 to 1.25.

Conventional perpendicularly magnetized films were manufactured based on the idea that the smaller the in-plane coercive force, the better the performance of the perpendicularly magnetized film. The superior S/N of the product of the present invention compared to the product constructed with This is presumed to be because a magnetic head with only a perpendicular magnetization component or a complete in-plane magnetization component cannot be realized, but is made up of a vectorial combination of both components.

The perpendicular magnetization film used in the present invention can be selected as appropriate except for the limitation on the value of Ha/HQ/, and any known manufacturing method and material can be applied.

Further, the present invention may be configured with the above-mentioned three-layered medium or may be configured without the soft magnetic layer, but it is not known in this field that a lubricant layer may be provided on the surface if necessary. This is a normal technique.

A more specific embodiment of the present invention will be described below.

A Go-Cr (Or 20 atoms) layer was formed on a 12-μm pounded polyethylene terephthalate (surface roughness is about 0.01 μm) using the high-frequency magnetronospanotary/magnetic method, and a magnetic tape with a width of 8% was formed. make.

Rotation/Ring (Cylinder diameter a an ) Equipped with a ring-shaped sendust head with a VC cast length of 0.2/1 m.

Track width 911m, recording wavelength 0.257zm, 0.3
Recording and playback of 3 levels: 6μm, Q・4s7zm.

S/N was measured.

Go-Cr thickness is Q, constant 311m, HO soil/H
The ratio of a/ is selected in the range of approximately 1 to 1.35, and Ha
S/N measurements were performed while varying the soil in the range of 25o ('Oe) to 9eo ('Oe). Figure 3 is an example of the measurement results, and is a diagram showing the relationship between S/N and Ha soil/Ha/ when JHc soil is selected at 55o (0°e).

Depending on the conditions and thickness of the Hc soil, the S/N value within the scope of the present invention can be improved from 45 dB to 52 dB.

Even if these parameters are changed, if Hc/Hc/ is selected from 1.05 to 1.25, an S/N of 45 dB or more can be secured. 80 section Ni-20 candy Fe lament o, 53μm
The above-mentioned Go-(ljr layer) was also confirmed, and 0.15 μm amorphous (Go9
It was confirmed that 54 dB from 4 s, dB can be obtained even with a vertical head having a main pole made of a sputtered film (0% Zr 10%).

As described above, according to this embodiment, Ha upper/Ha7 is 1.
By selecting a value between 0.06 and 1.25 and configuring a perpendicular magnetization film, the recording wavelength is 0.5 pm or less and 1011 m.
Even with narrow tracks below, a S/N of 45 dB or more can be achieved.

In addition to Go-Or, the present invention also applies to Go-V, Go
-Ti.

Go-Mo, Go-W, Go-Ni-
It was confirmed that Cr, Co-0, Go-Ni-0, etc. have similar effects. Further, in the above embodiments, the 4a tape was explained as an example, but the same effect can be obtained with magnetic disks and magnetic sorting.

Furthermore, the present invention can achieve a practical level even without the combination of a 3-layer medium and a vertical head, and can omit the formation of a soft magnetic layer that requires a thickness of 0.6 μm or more. This is a point that cannot be overlooked as an economic effect in terms of media production.

Effects of the Invention As described above, the present invention provides a perpendicularly magnetized film in which the axis of easy magnetization is perpendicular to the film surface, so that the ratio Hc±/Ha7 of the perpendicular coercive force Hc and the in-plane coercive force Hc/ is 1. 05 to 1.25
By making it so that, in short wavelength recording and reproduction,
It is possible to obtain a sufficient practical level of 37N, and its practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the perpendicular magnetization method, Fig. 2 is a diagram showing the hysteresis curve of the perpendicular magnetization film necessary for perpendicular recording, and Fig. 3 is a reproduction S in perpendicular recording using the medium of the present invention. /N and He
It is a figure showing the relationship of soil/Hc7. 1... Main magnetic pole, 4... Perpendicular magnetization film, 7...
・Magnetization curve in the vertical direction, 8... Magnetization curve in the in-plane direction. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
(Fig. 2, Fig. 3), o 1. I +, 2 + 3 months・”/)I C//

Claims (1)

[Claims] Ratio of the perpendicular coercive force HC on the perpendicular direction and the in-plane coercive force He/of a perpendicularly magnetized film whose axis of easy magnetization is perpendicular to the film surface IA Hc
A magnetic recording medium characterized in that ±/Hc7 is in the range of 1.05 (7) to 1.25 (7).