JPS62119758A - Coating type photomagnetic memory - Google Patents

Abstract

PURPOSE:To remarkably improve corrosion resistance by using orientable particle powder of yttrium-iron-garnet ferrite which is an oxide having the characteristic of an excellent photomagnetic effect as a material for a recording medium and forming the medium of a coating type. CONSTITUTION:The powder particles of the yttrium-iron-garnet (YIG; Y3Fe5O12) compd. which is the oxide magnetic material having excellent environmental resistance and of which the the specific crystal face is considerably grown are used. Said particles are mixed with an org. binder having heat resistance to prepare a magnetic coating compd. The coating compd. is coated on a hard or flexible medium substrate, by which the coating type photomagnetic memory is obtd. The YIG to be used as the raw material powder for the orientable photomagnetic medium material has an extremely high magnetooptic index and is superior in corrosion resistance to an amorphous alloy if the YIG is of a Bi substd. type.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rewritable coated magneto-optical memory using a coated media material that can be recorded and erased using laser light.

Conventional technology One of the high-density recording methods of the future is a non-contact magneto-optical method using laser light, which is a magnetic recording method that is fundamentally different from the conventional contact magnetic recording method using a magnetic head. The recording method is attracting attention. Disk-shaped magneto-optical media using MnB1 and amorphous metal films as media materials are seen as promising (for example, (W, Unger Journal of 7 Pride Physics) W, Unger et al., J , Ap'p1
．． Phys, 43 (61, 2875 (1972),)
.

Problems to be Solved by the Invention Media using these alloys as media materials have a drawback of poor environmental resistance, which is an essential drawback of the materials. In particular, there was a problem with moisture resistance.

In order to solve this drawback, studies have been made to use a garnet film such as YIG, which is an oxide magnetic material exhibiting a large magneto-optical effect, in place of the above-mentioned alloy film. YIG films with specific crystallographic crystal plane orientation are said to be promising as media for magneto-optical memory (Manabu Gomi et al., Abstracts of the 8th Japanese Society of Applied Magnetics, 1984, November),
P34-35), L However, the sputtered film has the disadvantage that it is necessary to select the underlying substrate material in order to orient a specific crystal plane. In addition, it is desired that media be formed in two shapes: a hard disk shape and a flexible tape shape.However, in the case of the thin film mentioned above, it is formed by sputtering or vapor deposition, so it is difficult to create flexible media. It was difficult.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention uses ia)ium iron garnet (Y), which is an oxide-based magnetic material with excellent environmental resistance.
Powder particles of IG; Y8Fes O,) type compound in which specific crystal faces have grown significantly are used, and this is mixed with a heat-resistant mechanical binder to create a magnetic paint, and this paint can be applied to hard or flexible media substrates. This is a coating-type magneto-optical memory that solves the above-mentioned problems by coating the above-mentioned materials.

Function The YIG used as the raw material powder for the oriented magneto-optical media material described above is, for example, a Bi-substituted YIG, compared to rare earth-transition metal amorphous magnetic materials that are currently being actively researched. If so, it has a significantly superior magneto-optic index and is characterized by superior corrosion resistance compared to amorphous alloys.

(Manabu Gomi, Kosuke Tanida, Masaki Abe, Abstracts of the 8th Japanese Society of Applied Magnetics, Academic Lectures (198'4.11).

Using this powder, a paint is made with an organic binder that is transparent to laser light, and this is applied onto a substrate in the same way as paint for coated magnetic recording media to manufacture and provide magneto-optical recording media. This will expand the scope of use of optical recording memory in the field of memory applications.

Conventionally, when magneto-optical media are fabricated by forming a thin film with magneto-optical properties with a fixed thickness on a flexible substrate, volumetric distortion occurs in the media itself due to distortion of the substrate, and as a result, magnetic It was difficult for magneto-optical media to emerge due to the deterioration in properties, but since the present invention is a coated magneto-optical media, the recording density is slightly lower, but the above-mentioned drawbacks are solved, and optical tape and optical disks can be used. The range of use is expanded to applications such as tsupi disks. Therefore, the present invention has important significance in the applied field of magneto-optical recording.

Example Examples of the present invention are shown below.

Yttrium iron garthnod with bismuth (Bi) ions substituted, synthesized by hydrothermal synthesis method, B j 1
．． 2 Y+, e Fes O1! As a powder, (11
1) The average diameter of the grown surface is 1.5 μm and the thickness is 0.
．． A paint was prepared by using tabular crystal particles with a size of 4 μm and dispersing them in a heat-resistant organic binder. Apply this paint to a width of 2. Ocm length 4. 0-marked glass plate (thickness 1.8cm
■), a polycarbonate plate (2.0m thick) with a width of 3.0cxa and a length of 4.0cm, or a width of 5.0cm. 0CI11
Length 20. It was coated on the surface of an Oa++ polytetrafluoroethylene film (thickness: 0.2 m) in a magnetic field and sufficiently dried to prepare a coated film sample of magnetic powder. A coating film sample with a polytetrafluoroethylene film as a base was cut into squares with a width of 1.0 cm and a length of 1.0 cm.
It was attached to a glass plate (thickness: 1.8 wm) with a length of 4.00 mm to prepare a sample for evaluation. Moreover, the coating film samples produced on the glass plate and the acrylic plate were used as samples for evaluation as they were.

X-ray diffraction was performed on the three different evaluation samples mentioned above. As a result, the X-ray diffraction pattern of Cu- using alpha rays for all samples has a sharp peak of the (444) plane in the range of 2θ = 25 to 60', and other peaks are concentrated, resulting in a small pattern. showed that.

In other words, the (44) crystallographically parallel to the (111) plane
4) It is a coating film of Y[G powder with oriented planes, and it is confirmed that the coating film has the same orientation as the oriented YIG film, which is promising as a magneto-optical memory made by the conventional sputtering method. Understood.

Each of these three different samples prepared in this way was placed in a direct current magnetic field perpendicular to the coated film, and the coated film surface was instantly heated to 300°C in an infrared condensing heating furnace, and then immediately cooled. . Spot light from an argon laser (spot diameter: 2
0 μm, irradiation power: 95 mW, irradiation time: 200 μs). As a result of observing the laser beam irradiated area using a polarizing microscope, it was found that for all the three different samples mentioned above, the laser beam irradiated area could be distinguished from the surrounding area (non-irradiated area) in a dot shape with high contrast. . In addition, the diameter of these irradiation-changed portions is approximately equal to the spot diameter of the irradiated laser beam, indicating that magneto-optical recording is possible with laser beams for all of the samples of the present invention. Understood.

To summarize the effects of the invention, the present invention uses yttrium iron garnet-based ferrite coordinating particle powder, which is an oxide with excellent magneto-optical properties, as a material for a recording medium, and
By using coated media, it is possible to significantly improve the corrosion resistance of the material compared to conventional alloy media.
The emergence of flexible media such as floppy disks and tapes will also become possible.

Claims (1)

[Claims] A paint made by mixing yttrium iron garnet (YIG; Y_3Fe_5O_1_2) powder particles with specific crystal planes grown with a heat-resistant organic binder is applied onto a transparent substrate or a flexible transparent film. A coated magneto-optical memory characterized by: