JPS63266656A - Magneto-optical recording medium and its recording method - Google Patents

Abstract

PURPOSE:To dispense with an external magnetic field impressing device, and further, to enable an overwrite by the frequency of mega hertz region by casting a recording laser after power-modulating or pulse-width-modulating it according to the direction of a magnetization, by which a recording layer is intended to be recorded. CONSTITUTION:It is constituted so as to be provided with a composite recording layer, consisting of a recording magnetic layer 5 and, at least, one auxiliary magnetic layer 7 which is the supply source of a recording magnetic field, on a substrate 1, and the recording laser 9 is due to be cast after being power-modulated or pulse-width- modulated according to the direction of the magnetization, by which the recording layer 5 is intended to be recorded. Namely, the combination of a transparent auxiliary magnetic layer 3 and other auxiliary magnetic layer 7, the directions of the magnetization of which are set opposite to each other, or the combination of a nonmetallic system auxiliary magnetic layer 4 and other auxiliary magnetic layer 7, or the like can be made into one pair, and can be used as the recording magnetic field supply source for the recording magnetic layer 5. Thus, the recording magnetic field can be inverted at high speed by the modulation of the recording laser 9 without using the external magnetic field impressing device, and the overwrite comes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magneto-optical recording medium in which heat generated by laser beam irradiation is recorded and reproduced using the magneto-optic effect, and a recording method thereof.

Conventional technology Magneto-optical recording media perform recording by irradiating the recording layer with laser light to locally raise the temperature of the recording layer to a temperature higher than the compensation temperature or around the Curie temperature, and magnetizing the recording layer in the irradiated area in the direction of the external magnetic field. , erasing is performed (thermomagnetic recording), and by irradiating a laser beam with a power lower than the laser power during recording and erasing, the polarization plane of reflected or transmitted light is rotated depending on the recording state (direction of magnetization) of the recording layer. Playback is performed by detecting.

Previously proposed methods for performing override operations include irradiating a continuously driven recording laser beam to locally increase the temperature of the recording layer, and applying an external magnetic field whose direction is modulated according to the signal. Thermomagnetic recording method and a composite recording layer consisting of a recording magnetic layer 61 and an auxiliary magnetic layer 62 as shown in FIG. 6, two external magnetic field applying devices 63 and 64 that apply magnetic fields in opposite directions, and power modulation according to signals A thermomagnetic recording method using a recording laser 65 (for example, the 34th
Proceedings of the Joint Conference on Regenerative Physics 28P-2L-3,
1987) etc.

Problems to be Solved by the Invention However, in the first conventional method, if a sufficient distance is provided between the external magnetic field application device and the magneto-optical recording medium, it is difficult to apply the necessary external magnetic field to the recording layer at frequencies in the megahertz region. Since it cannot be applied, override is impossible, and one solution 2
This method has the problem of increasing the size of the device because it requires two external magnetic field applying devices.

In view of the above problems, the present invention provides a magneto-optical recording medium that does not require an external magnetic field applying device and can be overridden at a frequency in the megahertz range, and a recording method thereof.

Means for Solving the Problems In order to achieve this object, the magneto-optical recording medium of the present invention has a composite recording medium consisting of a recording magnetic layer on a substrate and one auxiliary magnetic layer that serves as a recording magnetic field source. The recording method of the magneto-optical recording medium of the present invention is to irradiate the recording laser with power modulation or pulse width modulation depending on the direction of magnetization to be recorded in the recording layer.

Operation With this configuration, a combination of a transparent auxiliary magnetic layer and another auxiliary magnetic layer, or a combination of a nonmetallic auxiliary magnetic layer and another auxiliary magnetic layer, whose magnetizations are set in opposite directions, is used as a set for the recording magnetic layer. Since it can be used as a recording magnetic field supply source, the recording magnetic field can be quickly reversed by modulating the recording laser without using an external magnetic field applying device, and override can be performed. In other words, in the case of the pasted structure, the magnitude relationship between the magnetic field generated by the magnetization of the transparent auxiliary magnetic layer and the magnetic field generated by the magnetization of the auxiliary magnetic layer when the recording magnetic layer reaches the recording temperature can be determined for each layer by modulating the recording laser. By controlling the temperature relationship, the magnetization of the recording magnetic layer is overridden in the direction of the dominant magnetic field by reversing the direction.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a substrate made of glass or the like, 2 is a transparent protective layer made of a SiO film, 3 is a transparent auxiliary magnetic layer made of a garnet film such as YIG, and 4 is 5iOII.
A nonmagnetic layer consisting of I, 5 is TbFe, GdTbFe, T
bA recording magnetic layer made of a rare earth-transition metal ferrimagnetic film such as FeCo, 6 a nonmagnetic layer made of a SiO film, 7 a T
b An auxiliary magnetic layer made of a FeCo film or the like, 8 a protective layer made of a SiO film, 9 a laser beam, and each magnetic layer 3, 5.7
is a perpendicular magnetization film, and transparent auxiliary magnetic layer 3 and auxiliary magnetic layer 7
The magnetization directions are opposite to each other, and the Curie temperature of each is set higher than the Curie temperature of the recording magnetic layer 5.

Here, each layer on the substrate 1 was formed by a vapor deposition method and a sputtering method, and in particular, the transparent auxiliary magnetic layer 3 was formed by a sputtering method on the substrate 1 heated to about 300°C. The film thickness of each layer is 20 to 1,100 nm for the transparent protective film 2, 50 to 1,100 nm for the transparent auxiliary magnetic layer 3, and 1,100 nm for the nonmagnetic layers 4 and 6.
~20 nm, the recording magnetic layer 5 was set to 50 to 1100 nm, the auxiliary magnetic layer 7 was set to 50 to 1100 nm, and the protective layer 8 was set to 1100 nm.

The magneto-optical disk having the above configuration was irradiated with laser pulses of high power (indicated by A) and low power (indicated by B) for a certain amount of time, and the temperature of the recording magnetic layer 5 was brought to around one Curie temperature during the cooling process. Figure 2 shows a schematic diagram of the temperature distribution of each layer at the time, and Figure 3 shows a schematic diagram of temperature changes in the magnetic field created at the recording magnetic layer 5 by the magnetization of the transparent auxiliary magnetic layer 3 and the magnetization of the auxiliary magnetic layer 7. show.

In the case of irradiation with a high power laser pulse (A), the average temperature of the transparent auxiliary magnetic layer 3 is T4, and the temperature of the auxiliary magnetic layer 7 is T2. The magnetic fields created by the magnetization of No. 7 at the position of the recording magnetic layer 5 are H4 and H2, respectively.

Since H4 minus H2, the magnetic field as a sum is the auxiliary magnetic layer 7.
The direction of magnetization becomes the same as that of the recording magnetic layer 5 during the subsequent cooling process.
The magnetization is recorded in the direction of magnetization of the auxiliary magnetic layer 7. On the other hand, when irradiating with a low power laser pulse (B),
The average temperature of the transparent auxiliary magnetic layer 3 is T3, and the average temperature of the auxiliary magnetic layer 7 is T. From FIG. The sum becomes the direction of the transparent auxiliary magnetic layer 3, and in the subsequent cooling process, the magnetization of the recording magnetic layer 5 is recorded in the direction of the transparent auxiliary magnetic layer 3. In other words, the direction of magnetization of the recording magnetic layer can be set in any direction by power modulation of the recording laser pulse, making override possible.

In this embodiment, the transparent auxiliary magnetic layer 3. Recording magnetic layer 5. A magneto-optical recording medium having a composite recording layer consisting of three magnetic layers, the auxiliary magnetic layer 7, was used.In order from the light input side, the recording magnetic layer 5, the non-metallic auxiliary magnetic layer (oxide magnetic layer, etc.) .

Even when a magneto-optical recording medium having a composite recording layer consisting of three magnetic layers of the auxiliary magnetic layer 7 is used, the power modulation and pulse width modulation of the recording laser result in two-dimensional recording as shown in FIG.
Since the temperature distribution of each layer of the type is obtained, overriding according to the present invention is possible. Furthermore, when a ferrimagnetic auxiliary magnetic layer 7 having a temperature characteristic of magnetization as shown in FIG. 5a is employed, the recording magnetic layer 5. Auxiliary magnetic layer 7 or in turn transparent auxiliary magnetic layer 3. Even when using a magneto-optical recording medium having a composite recording layer consisting of the recording magnetic layer 5, the temperature distribution of each layer as shown in Figure 5c is obtained by power modulation and pulse width modulation of the recording laser, and the laser As a result of the direction of magnetization of the auxiliary magnetic layer 7 being reversed under the pulse irradiation state, the direction of the magnetic field generated by the magnetization is also reversed, so overriding according to the present invention is possible.

In this embodiment, the transparent auxiliary magnetic layer 3 is a garnet film, the recording magnetic layer 5 is a rare earth-transition metal ferrimagnetic film, and the auxiliary magnetic layer 7 is TbFeCo.

The transparent auxiliary magnetic layer may be a spinel ferrite film, hexagonal ferrite film, etc.; the recording magnetic layer 5 may be a garnet film, a spinel ferrite film, a Heusler alloy film, etc.; the auxiliary magnetic layer 7 may have appropriate magnetization temperature characteristics. It is also possible to use other perpendicularly magnetized films such as a transparent protective layer 2, a nonmagnetic layer 46, and a ZnS film, a Zn5e film, a nitride film, or other suitable oxide film as the protective layer 8. good.

Furthermore, the transparent protective layer 2 and the protective layer 8 can be omitted depending on the case.

Effects of the Invention The present invention creates two types of temperature distribution states in each layer in a composite recording layer consisting of a recording magnetic layer and a magnetic layer serving as a recording magnetic field supply source by power modulating or pulse width modulating a recording laser. In each state, the direction of the recording magnetic field generated by the magnetic layer of the recording magnetic field supply source is reversed to perform the recording operation, thereby realizing override without an external magnetic field applying device.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of a magneto-optical recording medium in one embodiment of the present invention, FIG. 2 is a schematic diagram of the temperature distribution of each layer in the magneto-optical recording medium in this embodiment, and FIG. 3 is a schematic diagram of the temperature distribution of each layer in the magneto-optical recording medium in this embodiment. Figure 4 is a schematic diagram of the temperature change of the magnetic field created at the position of the recording magnetic layer by the magnetization of the transparent auxiliary magnetic layer and the magnetization of the auxiliary magnetic layer in a magneto-optical recording medium. FIG. 5 is a schematic diagram of the temperature characteristics of the magnetization of the auxiliary magnetic layer and the temperature distribution of each layer in a magneto-optical recording medium according to another embodiment of the present invention, and FIG. 6 is a diagram of the configuration of a conventional override method. . 1...Substrate, 2...Transparent protective layer, 3.
...Transparent auxiliary magnetic layer, 4...Nonmagnetic layer,
5... Recording magnetic layer, 6... Nonmagnetic layer,
7...Auxiliary magnetic layer, 8...Protective layer, 9
...Laser light. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2 Figure 3 X Figure 14 Figure 5

Claims (7)

[Claims] (1) A method for recording a magneto-optical recording medium, characterized in that a recording laser is irradiated with power modulation or pulse width modulation according to the direction of magnetization to be recorded on a recording layer. (2) A magneto-optical recording medium having, on a substrate, a composite recording layer consisting of a recording magnetic layer and at least one auxiliary magnetic layer serving as a recording magnetic field supply source. (3) The magneto-optical recording medium according to claim 2, characterized in that at least one non-metallic magnetic layer is used as the auxiliary magnetic layer. (4) Claim 2, characterized in that the composite recording layer uses a structure consisting of a transparent auxiliary magnetic layer, a nonmagnetic layer, a recording magnetic layer, a nonmagnetic layer, and an auxiliary magnetic layer in order from the light input side. The magneto-optical recording medium described above. (5) As a composite recording layer, a structure consisting of a recording magnetic layer, a nonmagnetic layer, a nonmetallic auxiliary magnetic layer, a nonmagnetic layer, and an auxiliary magnetic layer is used in this order from the light input side. 2. The magneto-optical recording medium according to item 2. (6) The magneto-optical device according to claim 2, characterized in that the composite recording layer is composed of a transparent auxiliary magnetic layer having ferrimagnetism, a nonmagnetic layer, and a recording magnetic layer in order from the light input side. recoding media. (7) Magneto-optical recording according to claim 2, characterized in that the composite recording layer is composed of a recording magnetic layer, a non-magnetic layer, and an auxiliary magnetic layer having ferrimagnetism in order from the light input side. Medium.