JPH04106743A - magneto-optical recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to a magneto-optical recording medium suitable for a magneto-optical recording system capable of overwriting 1 using a diamagnetic field.

[Conventional technology]

Several methods have been proposed as magneto-optical recording methods, one of which is a diamagnetic field recording method in which recording and erasure are performed using the diamagnetic field of the magneto-optical recording medium itself. In this method, by irradiating the recording medium with a laser beam, the domain wall energy is changed together with the energy due to the demagnetizing field, and the magnitude relationship between these causes a force that contributes to the expansion and contraction of the magnetic domain, and this is used to generate an overload. Trying to achieve light (, snow, D, 5chu
1. tZ+J.

Appl, Phys, 63(8), 1988.4
．． 15. p, 3844-3846).

On the other hand, the present applicant has filed Japanese Patent Application No. 2-37930 and Japanese Patent Application No.
In No. 64959, we proposed a new magneto-optical recording method that performs overwriting using a diamagnetic field. The former method is an optical method in which - information signals are recorded in the information recording layer of a magneto-optical recording medium using focuses with upward magnetization and pits with downward magnetization, corresponding to the z-value signal "I11 or 110I+". In the magnetic recording method, when writing it1n of a binary signal, a single pulse laser beam is irradiated to the signal writing position, and when writing a signal "0", a continuous pulse is irradiated from the signal writing position to the next signal writing position. Overwriting is possible by recording by irradiating laser light. The latter method is a magneto-optical recording method in which a magnetic recording pattern is formed by irradiating the perpendicularly magnetized film of a magneto-optical recording medium with light. When performing recording by irradiating light, the direction of magnetization to be recorded changes from downward to upward or from upward to downward with respect to the medium surface.

By changing the light irradiation method such as the spot diameter, pulse width, irradiation power, and whether a single pulse or continuous pulse of irradiation light is used, signals can be recorded and overwritten.

[Problem to be solved by the invention]

As mentioned above, in the diamagnetic field recording method, a force is generated in the normal direction of the domain wall due to the magnitude relationship between the diamagnetic field energy and the domain wall energy in the magnetic film of the magneto-optical recording medium, and if this is larger than the coercive force, the force is generated in the direction of the force. Domain wall movement occurs. Generally, domain wall energy produces a force in the direction of contracting the magnetic domain, and demagnetizing field energy produces a force in the direction of expanding the magnetic domain. Therefore, the former facilitates signal erasure with respect to overwriting, and the latter facilitates recording. However, because the demagnetizing field energy increases as the bit becomes smaller, there is a phenomenon in which the bit is not completely erased and remains as a minute magnetic domain, which causes a decrease in reliability.

In addition, with the magneto-optical recording method of Japanese Patent Application No. 2-37930 (former) previously proposed by the present applicant, overwriting can be performed efficiently with a simple device configuration, but the demagnetizing field is weakened and the cylindrical magnetic domain is It is desirable to

Furthermore, the patent application Hei 2-64, which was also proposed by Mizuhimoto
The magneto-optical recording method of No. 959 (the latter) has the effect of freely controlling the magnetization direction of the recording medium by changing the light irradiation method, but due to the demagnetizing field from the track section, l→ The conditions for rewriting 0 and rewriting 0 → 1 are different.

In order to further reduce write errors, it is desirable to perform these operations under the same conditions.

The present invention was made in order to solve the problems of the conventional technology, and an object of the present invention is to provide a magneto-optical recording medium using a diamagnetic field recording method, which eliminates unerased bits and significantly reduces write errors. shall be.

[Means to solve the problem]

To achieve the above object, according to the present invention, in a magneto-optical recording medium used in a magneto-optical recording method in which information is overwritten using a diamagnetic field of a magnetic film,
A magneto-optical recording medium is provided in which the magnetization direction of the recording section in an initial state and the magnetization direction of the track section and its vicinity are set to be opposite to each other.

Further, according to the present invention, in a magneto-optical recording medium used in a magneto-optical recording method that uses a demagnetizing field of a magnetic film to overwrite information, magnetization of adjacent track portions and their vicinity A magneto-optical recording medium characterized in that the directions are set in opposite directions is provided.

[Effect]

In the present invention, the magnetization directions of the recording section, the track section, and the vicinity thereof in the initial state are reversed, and the magnetization directions of the adjacent track section and the vicinity thereof are reversed. The demagnetizing field applied to the bit from the vicinity is effectively suppressed, no bit remains unerased, writing errors are significantly reduced, and the above problem is solved.

〔Example〕 The present invention will be explained in more detail below with reference to Examples.

FIG. 1 is a perspective sectional view schematically showing a part of a magneto-optical recording medium according to an embodiment of the present invention. In the figure, 1 is a magnetic film (perpendicular magnetization film), 2 is a substrate, 3 is a recording part (land part), 4 is a track part and its vicinity, and 5 is a bit formed in the recording part 3.

The structural feature of this embodiment is that the direction of magnetization of the recording section 3 in the initial state (unrecorded state) is opposite to the direction of magnetization of the track section and its vicinity 4. As mentioned above, in the magnetic domain structure of a magneto-optical recording medium, when the demagnetizing field energy is smaller than the domain wall energy, the bit generally receives a force in the direction of contraction, but as the bit becomes smaller, the demagnetizing field energy increases, so the demagnetizing field energy increases during erasing. This is the cause of unerased data. In this embodiment, since the magnetization directions of the recording section 3, the track section, and its vicinity 4 in the initial state are defined as described above, the demagnetizing field from the track section and its vicinity 4 is applied to the formed bit. is kept small, and there is no unerased area when erasing.

FIG. 2 shows the relationship between the bit radius R and the magnitude Hd of the demagnetizing field applied to the bit domain wall when the formed bit is circular. However, the track period is 1.6μ
s, and the magnetization in the recording section is in the form of a band with a radius 1 threshold. Curve A in the figure is the case of this embodiment, that is, the case of a recording medium in which the direction of magnetization in the initial state is opposite between the recording section 3 and the track section and its vicinity 4, and curve B is the case of the conventional case. That is, this is the case of recording media in which the directions of magnetization in both initial states are the same. As is clear from this figure, with the configuration of this embodiment, the influence of the demagnetizing field from the track portion and its vicinity 4 on the bit is considerably reduced.

In order to set the initial state of magnetization of the magnetic film 1 as shown in FIG. 1, for example, immediately after manufacturing a recording medium having a magnetic film whose magnetization is oriented in one direction throughout, a laser beam of a predetermined power is irradiated. This can be done by applying a magnetic field of a predetermined strength and continuously reversing the magnetization only in the track portion and its vicinity.

FIG. 2 is a perspective sectional view schematically showing a part of a magneto-optical recording medium according to another embodiment of the present invention. In the figure, 11 is a magnetic film (perpendicular magnetization film), 12 is a substrate, 13 is a recording section (runt section), and 14 is a track section and its vicinity.The bits formed in the recording section 13 are omitted here. be.

The structural feature of this embodiment is that the magnetization directions of adjacent track portions and their vicinity 14 are opposite to each other. With this configuration, the recording section 1
At the center of the bit formed at 3, the demagnetizing fields from adjacent track sections and their vicinity 14 cancel each other out. Therefore, as in the embodiment shown in FIG. 1, it is possible to achieve the intended purpose.

〔Effect of the invention〕

According to the present invention, since the magnetization of the recording section and the track section and their vicinity in the initial state are opposite to each other,
In addition, since the magnetization of adjacent track parts and the vicinity thereof is made to be in opposite directions, the influence of the demagnetizing field from the track part and the vicinity thereof on the formed bit is reduced, and no bit remains unerased. , it becomes possible to reduce write errors.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a part of a magneto-optical recording medium according to an embodiment of the present invention, and FIG. 2 is the size of a bit (magnetic domain radius) formed in the magneto-optical recording medium of FIG. 1. FIG. 3 is a graph showing the relationship between the magnitude of the demagnetizing field at the bit domain wall in comparison with that of a conventional recording medium, and FIG. FIG. 1.11. Magnetic film 2.12. Substrate 3.13. Recording section (land section) 4.14 Track section and its vicinity 5. Pinto patent applicant Rico Co., Ltd.

Claims (2)

[Claims] (1) In a magneto-optical recording medium used in a magneto-optical recording method that uses the diamagnetic field of a magnetic film to overwrite information, the magnetization direction of the recording section and the magnetization of the track section and its vicinity in the initial state A magneto-optical recording medium characterized in that the direction is set in the opposite direction. (2) In a magneto-optical recording medium used in a magneto-optical recording method that uses the diamagnetic field of a magnetic film to overwrite information, the magnetization directions of adjacent track portions and their vicinity are opposite to each other. A magneto-optical recording medium characterized by: