JPH05120744A - Magneto-optical memory element - Google Patents

Abstract

PURPOSE:To eliminate the need for a magnetic field impressing device, to miniaturize the device and to thin the device by integrating a memory layer having perpendicular magnetic anisotropy and a substrate consisting of a magnet having a permanent magnetic field, thereby effectively utilizing the magnetic field generated by the magnet. CONSTITUTION:This magneto-optical memory element is formed by laminating a dielectric film 2, a magnetic recording film 3 and a dielectric film 4 on a magnet substrate 1. The magnetization direction of an auxiliary magnetic layer for which the magnetization direction of an initialization layer forming the film 3 is transferred to the recording later when the element is irradiated with the light beam of a low level from the film 4 side. On the other hand, the magnetization direction of the substrate 1 is transferred to the auxiliary magnetic layer and is further transferred on the recording layer when the element is irradiated with the light beam of a high level. Thus, the magnetization direction of the recording layer is recorded toward the initialization layer or the substrate 1 by the intensity of the light beam. Thus, the need for an initializing magnet and a bias magnet for impressing recording magnetic fields is eliminated and the device is miniaturized and the device is thinned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overwritable magneto-optical storage element such as a magneto-optical disk or a magneto-optical card adapted to a magneto-optical recording / reproducing apparatus using an optical modulation system.

[0002]

2. Description of the Related Art Conventionally, for example, in an exchange coupling type optical modulation overwritable optical magnetic disk, it is necessary to provide an external magnet such as a permanent magnet or an electromagnet for the initialization magnetic field and the auxiliary magnetic field at the time of recording. Yes (Proceedings of the Joint Lecture on Applied Physics (1987) 28p-ZL-3).

As shown in FIG. 5, this magneto-optical disk has a recording magnetic film 5 including a memory layer 51 and an auxiliary layer 52.
When recording is performed by overwriting in the recording / reproducing apparatus on the memory layer 51 which has already been recorded, the magnetization of the auxiliary layer 52 is first performed by the auxiliary magnetic field applying apparatus 56 having the initial auxiliary magnetic field Hini. Is aligned with the direction of the initial auxiliary magnetic field Hini. Next, the magnetic field applying device 5
By applying a recording magnetic field Hb by 5 and irradiating a light beam of a constant intensity through the lens 54, the magnetization direction of the memory layer 51 is reversed and recording is performed. At this time, if the intensity of the light beam is low, the memory layer 5
The magnetization direction of No. 1 follows the direction of the initial auxiliary magnetic field Hini of the auxiliary layer 52, and when the intensity of the light beam is high, the magnetization direction of the memory layer 51 becomes the recording magnetic field Hb.

On the other hand, in order to eliminate the need for the auxiliary magnetic field applying device 56, a magneto-optical disk having a recording magnetic film having a four-layer structure having an initialization layer has been developed (The 13th Annual Meeting of the Applied Magnetics Society of Japan). Summary (1989) 23aC-4). When recording is performed by overwriting using this magneto-optical disk, the magnetization direction of the initialization layer is transferred to the information recording layer when the intensity of the light beam is set to a low level. On the other hand, when the intensity of the light beam is set to a high level, the magnetization of the information recording layer is aligned in the magnetization direction of the recording magnetic field applying device provided in the recording / reproducing device, and recording is completed.

[0005]

However, in the magneto-optical disk having the above-mentioned conventional structure, the recording / reproducing apparatus requires the initialization magnetic field applying apparatus and the recording magnetic field applying apparatus. In particular, since a strong magnetic field (1 kOe or more) is required for the initializing magnetic field, a large magnet must be provided in the initializing magnetic field applying device. Therefore, there is a problem that there is a limit to downsizing and thinning of the recording / reproducing apparatus by these magnetic field applying apparatuses.

[0006]

In order to solve the above problems, a magneto-optical storage element according to the present invention has a permanent magnetic field in a magneto-optical storage element having a storage layer having perpendicular magnetic anisotropy. It is characterized by having a substrate made of a magnet.

[0007]

With the above structure, when recording is performed on the magneto-optical storage element, since the storage layer and the substrate made of the magnet are integrated, there is no conventional gap between the storage layer and the magnet. The magnetic field generated by the magnet is effectively used. Further, since the conventional magnetic field applying device in the recording / reproducing device is unnecessary, the space can be effectively used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

As shown in FIG. 1, a magneto-optical disk, which is a magneto-optical storage element according to the present invention, has a dielectric film 2, a recording magnetic film 3 as a storage layer, and a dielectric film on a magnet substrate 1. Four
Has a structure formed in this order.

The magnet substrate 1 is made of, for example, a plastic in which a rare earth magnet (Shin-Etsu rare earth magnet, manufactured by Shin-Etsu Chemical Co., Ltd.) is impregnated.
It has a magnetic field strength of 600 [Oe], and has a magnetic field direction parallel to the thickness direction of the substrate and downward in the drawing.

The dielectric films 2 and 4 are protective films made of nitrides such as SiN _x and AlN, SiO, ZnS (Se) or BaTiON, and each has a film thickness of about 50 nm.

For example, as shown in FIG. 2, the recording magnetic film 3 has four layers in which a recording layer 7, an auxiliary magnetic layer 8, a switching layer 9 and an initialization layer 10 are sequentially laminated from the side irradiated with a light beam. It has a structure.

The recording layer 7, the auxiliary magnetic layer 8 and the switching layer 9 each have perpendicular magnetic anisotropy, and their magnetization directions are upward or downward in the figure. And the recording layer 7
Is made of DyFeCo, TbFe, TbDyFeCo, or the like and has a thickness of 10 nm to 100 nm. The auxiliary magnetic layer 8 is made of DyFeCo, TbFeCo, G
It consists of dDyFeCo or GdTbFeCo, etc.,
It has a thickness of 10 nm to 100 nm. The switching layer 9 is made of TbFeCo, GdFe or DyF.
It is made of eCo or the like and has a thickness of 10 to 50 nm.

Further, the initialization layer 10 is made of TbCo, GdC.
It is made of o or GdTbCo or the like, has a thickness of 10 to 150 nm, and its magnetization direction is upward in the figure, and does not reverse during operation.

When recording is performed on the magneto-optical disk having the above structure by overwriting, the dielectric film 4 is formed on the magneto-optical disk.
A light beam is emitted from the side. At this time, when the intensity of the light beam is low, the magnetization direction of the auxiliary magnetic layer 8 from which the magnetization direction of the initialization layer 10 was transferred via the switching layer 9 by the exchange coupling is transferred to the recording layer 7. It On the other hand, when the intensity of the light beam is high, the initialization layer 10
The magnetization direction of is blocked by the switching layer 9, and the magnetization direction of the magnet substrate 1 is transferred to the auxiliary magnetic layer 8.
Then, the magnetization direction of the auxiliary magnetic layer 8 is transferred to the recording layer 7. Therefore, depending on the intensity of the light beam, the magnetization direction of the recording layer 7 is the direction of the initialization layer 10 (upward) or the magnet substrate 1.
Recording is performed according to the direction (downward).

In this embodiment, a rare earth magnet is used as the material of the magnet substrate 1, but the material is not limited to this, and the recording magnetic film 3 is used.
Any material may be used as long as it has a magnetic field having a magnitude corresponding to. Although the above rare earth magnet is impregnated in plastic, the magnet substrate 1 may be composed of only the rare earth magnet.

Further, although the recording magnetic film 3 having a four-layer structure has been described, the recording magnetic film 3 is not limited to this and has a single-layer structure.
It may have a two-layer structure or a three-layer structure. In this case, an initialization magnetic field applying device may be provided if necessary.

Further, the magneto-optical storage element of the present invention may have a structure in which a transparent substrate 5 is further provided on the dielectric film 4, as shown in FIG.

FIG. 4 shows an example of an optical hard disk device in which the magneto-optical storage element of the present invention is sealed in the device. In FIG. 4, a magneto-optical disk 11 including a magnet substrate 12 and a recording film 13 having a four-layer structure formed on the magnet substrate 12.
Is sealed in the optical hard disk drive together with the optical head 16 and the access mechanism 15.

When recording / reproducing is performed on the magneto-optical disk 11 in the above-mentioned optical hard disk device, the spindle mechanism 14 rotates the magneto-optical disk 11, and the access mechanism 15 causes the optical head 16 to move the magneto-optical disk 11 to the magneto-optical disk 11. A predetermined position is accessed, and a light beam is applied to the recording film 13.

As described above, in this optical hard disk device, since the initialization magnet and the bias magnet for applying the recording magnetic field are unnecessary, the device can be made compact and thin.

[0022]

As described above, the magneto-optical storage element according to the present invention has a structure including a substrate made of a magnet having a permanent magnetic field.

Therefore, since the memory layer and the substrate composed of the magnet are integrated, the magnetic field generated from the magnet is effectively utilized, and the effect of increasing the magnetic field application efficiency is exhibited.

Further, since the conventional magnetic field applying device in the recording / reproducing device is unnecessary, space can be effectively used,
As a result, the effect of facilitating downsizing and thinning of the device is also achieved.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing the structure of a magneto-optical disk of the present invention.

FIG. 2 is a schematic explanatory view showing a configuration of a recording magnetic film 3 of FIG.

FIG. 3 is a schematic explanatory view showing another configuration of the magneto-optical disk of the present invention.

FIG. 4 is a schematic perspective view showing an optical hard disk device using the magneto-optical disk of the present invention.

FIG. 5 is a schematic explanatory view showing a configuration of a conventional magneto-optical disk.

[Explanation of symbols]

 1 magnet substrate 3 recording magnetic film (memory layer)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junji Hirokane 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Kenji Ota 22-22 Nagaike-cho, Abeno-ku, Osaka, Osaka Within the corporation

Claims (1)

[Claims] 1. A magneto-optical storage element having a storage layer having perpendicular magnetic anisotropy, comprising a substrate made of a magnet having a permanent magnetic field.