JPS5979445A - Photomagnetic memory element - Google Patents

Abstract

PURPOSE:To enable sufficient reduction of light reflected at the surface of a substrate by coating the surface side of the substrate with a film same in material as a transparent dielectric film, and using this film for a reflection preventing film. CONSTITUTION:This element is composed of a transparent substrate 1 of a glass plate, a transparent dielectric film 2 made of SiO, a thin amorphous alloy film 3 made of Gd-Tb-Dy-Fe, a transparent dielectric film 4 made of SiO2, and a metallic reflective film 5 made of Cu, etc. 6 in the figure is the first coat made of SiO same in material as the film 2 formed to 100-110nm thickness, and 7 is the second coat made of SiO2 same in material as the film 4 formed to 130- 140nm thickness. In the photomagnetic memory element of this structure, the first and second coats 6, 7 act as light reflective film, and hence, they can sufficiently reduce the light reflected with the surface of the substrate not contributing to sampling of information.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magneto-optical storage element that records or erases information using thermal energy and reproduces information using interaction between light and magnetism.

<Prior Art> In recent years, research and development of optical memory devices capable of high density, large capacity, and high speed access have been actively conducted in various fields. Among these, magneto-optical memory devices capable of recording, reproducing, and erasing information are considered promising because they can be used as file memories for characters and images, video disks, and the like.

The storage material of this magneto-optical memory device is GdCo.

Amorphous alloy thin films of rare earths and transition metals such as TbFe, GdTbFe, and TbDyFe are suitable. This is because the amorphous alloy thin film of rare earths and transition metals has an axis of easy magnetization in the direction perpendicular to the film surface, and because it is amorphous, there is no grain boundary noise, and the laser power required for recording can be reduced. This is because it has such excellent properties. However, when the above-mentioned amorphous alloy thin film of rare earth and transition metals is used as a memory material, there is a drawback that the Kerr rotation angle, which is a magneto-optical effect, is small at 0.2 to 0.3 degrees, and the quality of the reproduced signal is not good. . In order to improve the quality of this reproduced signal, an element structure called a reflective film structure has traditionally been adopted in memory elements (Japanese patent application No. 5
5-85695). FIG. 1 is a partial side sectional view of a conventional magneto-optical memory element having a reflective film structure. In the figure, 1 is a transparent substrate, 2 is a transparent dielectric film having a higher refractive index than the transparent substrate 1, 3 is an amorphous rare earth-transition metal alloy thin film, 4 is a transparent dielectric film, and 5 is gold 17. 'j Sogawa 11・↓゛j. In a magneto-optical memory element with this structure, non-IM sound '[alloy li, l
I', lj, "j 3 is enough l:, 11 ri, sub-)
The light incident on the lever amorphous V'↓alloy l', 'lII, ゛3 passes through -116.

/) Birth light is reflected by the surface of the amorphous alloy thin film 3 and the Kerr effect II! : and amorphous alloy thin 11ff: Passing through 3 is gold hJ + anti-11111.1゛! 5 and reflected i
By passing through f4 and the amorphous alloy thin film 3, the Kerr rotation angle (Ll!) becomes several times larger than that of a simple Kerr effect, depending on the combined size of the Faraday effect (1↓). Crystalline alloy ->j17111','53 on 711 shiimei' body film 2) 7- has the function of increasing the rotation angle (IEEE Trans, on Rla
g.

Vol-16No5 1980 PI+94). - As an example, the transparent substrate 1 is a glass plate,
Ji light dielectric +1yH2 represents 1100n Si0, amorphous Ic1 alloy thin +1ejj 3 represents I2.5 nm Q
cl T l) I) y F e, No2 Closed Course Electrical Materials 11 History 4, 30 nm S t O2, metal anti!
In '141, in a configuration in which 'i 5 was made of 4 Q nm Cu, the Kerr rotation: li, increased to 75 degrees for angular force.

The magneto-optical memory element having the 2 anti-1:1.11 structure has the advantage of increasing the Kerr rotation 11j, but has the disadvantage that the anti-ρ1j optical phrase cannot be sufficiently obtained.

That is, in the double structure shown in FIG. 1, when the Kerr rotation angle increased to 175 degrees, the recurved η,j light decreased to about 5%.

However, since the reflection of light on the surface of the transparent plate 1 made of glass is about 4%, the amorphous alloy R17,11
The anti-body 1 light that is anti-η,j and contains information at 1y53 and the anti-4, I light that is anti-fang 1 and does not contain information on the surface of the transparent substrate 1 have the same light intensity value, and information8'+J'F'4 students began to experience problems.

<Eye [White] The present invention aims to solve the above-mentioned conventional drawbacks by
・Jli memorization closing lecture provided inside the element
This is a new and useful method that is the same as (111 force of /1'1'''1 is also formed on the substrate surface and is easy to manufacture) and can sufficiently reduce the non-n and I light on the substrate surface. The purpose is to present the element structure.

<Example> An example of the optical memory element according to the present invention will be described below.

FIG. 2 shows a side view of an embodiment of the magneto-optical distributing element according to the present invention. In the same 12<1, 1XIS of the 4f:i formation which is the same as the J+''i formation in Fig. 1 ('' is indicated with the same symbol. Furthermore, the magneto-optical arrangement tC and the element in ε1-2 are shown as〕')'i' IJJ board l board convex guide) and rank are provided. Also, transparent substrate 4th glass plate 1. Insulated electric body 1115'52 is S10, amorphous P
i combination <l 卜'+j7 +pY, j 31koG (1゛1M
)yFe S transparent dielectric nvj4LJ, S +02,
Gold bending resistance J'l, IIE' 5 is Cu. In the same figure, SiO, which is the same material as the transparent dielectric film 2, is
The first coating is formed using ~IIOnm Lu Jj IE+', and 7 is the same -H as the transparent dielectric 11ψ4.
'S 5L02 was coated with a thickness of 130 to 140 nm. :j. Magneto-optical storage element with this structure (''''-Coating 11 of memory 1!
6 and second coating +1v57 is anti-4, l prevention vs, l
! ′: Since the light acts as follows, it is possible to sufficiently reduce the reflected light that is reflected on the surface of the transparent substrate 1 and does not contribute to the collection of information. The first coating film 6 and the second coating 11
j and 7 are formed so that the film thickness d of each is equal to d-λ/4n, where λ is the laser wavelength used and n is the refractive index. Also, during the first iff, ゛! 6) Rivi t1~
2's 7th t'; +11°, 'S7 can fulfill the if and s F of anti-body and 1 prevention even if only one of them is present.

Here, the quality of the first coating 111°7!6 and the second coating film 7 can be variously changed depending on the quality of the transparent dielectric films 2 and 4. For example, two layers II'', 'j consisting of TiO2, Si3N4 or MgFe, 3Na
F; AlF3' (ice crystal) Even if it is a single layer of 1%'j of Alj, it will not work. Other structures, such as a three-layer film or a multilayer film of more than 1%, are also acceptable.

Further, in the following description, the transparent substrate I is made of a glass plate, but the transparent substrate 1 may be a resin substrate made of PMMA resin, polycarbonate resin, or the like. Here, the transparent Ji (if the plate 1 is made of I''l'tfMA resin, since the PMMA resin has high hygroscopicity, as shown in Fig. 1) is inserted into the transparent element. J
When the films 2 to 5 are formed and then taken out into the atmosphere, the substrate l absorbs moisture and warps into a convex shape with the films 2 to 5 inward in each coating 113. However, as in the structure of FIG. 2, the first coating 111. ′! If 6, the second coating li+, and 7 are formed in a vacuum, the above-mentioned warping can be prevented. That is, in this case, the first one starts (
11・′・”16 and O・Second Him）5J11・1.lj
7 has the function of preventing the front surface of the J-tome substrate 1 from fouling + 1 - preventing the transparent substrate 1 from warping in a ratio of 1.1':l.

According to the present invention, it is possible to reduce the 4.1 light that is reflected on the surface of the transparent substrate and does not contain information, so that the quality of information can be improved. Furthermore, the structure of the magneto-optical memory element according to the present invention (1) is easy to manufacture since a film having the same phase as the 3B bright dielectric film provided inside the element is formed on the substrate surface, and the manufacturing cost is low. It is also advantageous in terms of 1.

[Brief explanation of the drawing]

Fig. 1 shows a partial side cross-sectional view of a conventional magneto-optical memory element, and Fig. 2 l)<j shows a partial side cross-sectional view of an embodiment of the magneto-optical memory element according to the present invention. In the figure, I: Transparent substrate, 2: Transparent dielectric model, 3: Amorphous alloy thin film, 4: YFI clear dielectric film, 5: Metal reflection law °j, 6: Mu (J1 Coating 11i'j, 7: Second coating film. Patent attorney Yoshihiko Fukushi (and 2 others) Fig. 1 Fig. 2

Claims (1)

[Claims] ] In a magneto-optical memory element in which a magnetic thin film and a transparent dielectric layer adjacent to the magnetic thin film are coated on the back side of a substrate, a film made of the same material as the transparent dielectric film is coated on the front side of the substrate. A magneto-optical memory element characterized in that the formed film is used as a fouling prevention film.