JPH0834014B2 - Magneto-optical storage element - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical storage element capable of recording, reproducing and erasing information by using laser light.

[0002]

2. Description of the Related Art In recent years, development of an optical storage element capable of recording, reproducing and erasing information has been actively promoted centering on a magneto-optical storage element. An element having a reflective film structure has been highly evaluated in the structure of this magneto-optical storage element.

FIG. 2 shows a side view of an example of an element having a reflective film structure. In the figure, reference numeral 1 is a transparent substrate made of glass or acrylic resin, 2 is a transparent thin film of SiO, SiO ₂ , Si ₃ N ₄ or the like, 3 is GdTbFe, TbDyFe, GdCo, Tb.
Amorphous magnetic thin film made of rare earth / transition metal alloy such as Fe or GdTbDyFe 4 is SiO, SiO ₂ , Si ₃ N
Transparent thin films such as ₄ and 5 are reflective films of Cu, Al, Au, Ag and the like.

Since the thickness of the amorphous magnetic thin film 3 of the above-mentioned reflective film structure is very thin, about 100 Å, the incident laser light incident from the transparent substrate 1 side causes the amorphous magnetic thin film 3 to pass through the amorphous magnetic thin film 3. The light that has passed through is reflected by the reflective film 5. Therefore, the Kerr effect of the incident laser light reflected on the surface of the amorphous magnetic thin film 3 is transmitted, and the Kerr effect transmitted through the amorphous magnetic thin film 3 is reflected by the reflective film 5 and again the amorphous magnetic thin film. The Faraday effect of the light passing through No. 3 causes a synergistic effect to increase the Kerr rotation angle. In addition, the light interferes inside the transparent thin film 2, which also has the effect of increasing the Kerr rotation angle.

[0005]

The element having the above-mentioned reflective film structure has an extremely excellent structure from the viewpoint of the magneto-optical effect. On the other hand, however, the characteristic deterioration due to the oxidation of the amorphous magnetic thin film 3 occurs. The big one has proven to be a drawback. That is, outside air penetrates through the reflective film 5 and the transparent thin film 4 to oxidize the amorphous magnetic thin film 3, or the oxygen contained in the reflective film 5 and the transparent thin film 4 is converted into the amorphous magnetic thin film. The phenomenon of oxidizing 3 occurs. If the amorphous magnetic thin film 3 is oxidized, the coercive force is lowered, making it difficult to reproduce due to the magneto-optical effect. In an extreme case, the perpendicular magnetic anisotropy of the amorphous magnetic thin film 3 is completely lost and both recording and reproducing are unsuccessful. There is a remarkably inconvenient problem that it becomes possible.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a magneto-optical storage element having a structure capable of preventing the oxidation of an amorphous magnetic thin film.

[0007]

In order to achieve the above-mentioned object, the present invention provides an amorphous magnetic thin film made of a rare earth / transition metal alloy having an easy axis of magnetization in a direction perpendicular to the film surface on a transparent substrate. A formed magneto-optical storage element, comprising a transparent thin film adjacent to the amorphous magnetic thin film, wherein the transparent thin film contains at least one of Ti and a rare earth metal. Is.

[0008]

[Function] At least one of Ti and a rare earth metal is provided in the transparent thin film provided on the transparent substrate in proximity to the amorphous magnetic thin film made of a rare earth / transition metal alloy having an easy axis of magnetization in the direction perpendicular to the film surface. By containing, the invading oxygen can be consumed by Ti or the rare earth metal in the transparent thin film.

[0009]

1 is a side view of an embodiment of a magneto-optical memory device according to the present invention. In the figure, reference numeral 1 is a transparent substrate made of glass, acrylic resin or the like, and 2 is SiO or S.
Transparent thin films such as iO ₂ , Si ₃ N ₄ , 3 are GdTbFe, T
Amorphous magnetic thin film made of rare earth / transition metal alloy such as bDyFe, GdCo, TbFe, GdTbDyFe, 4
Is a transparent thin film of SiO, SiO ₂ , Si ₃ N _4, etc., 6 is C
Ti, M in a metal film of u, Al, Au, Ag, SUS, etc.
g, a rare earth metal (Gd, Tb, Dy, Ho, Y) and other oxidizable metal substances.

Here, the inclusion of the easily oxidizable metal substance may be carried out in the transparent thin film 2, or in the transparent thin film 4.
The transparent thin film 2, the transparent thin film 4, and the reflective film 6 may be used for any two or more films. In addition, the transparent thin film 2 may be omitted in the configuration shown in FIG. In order to confirm the effects of the invention described above, the results of measuring the degree of change in the coercive force of the amorphous magnetic thin film when stored in a high temperature state are shown in FIGS. 3 and 4. In the figure, the horizontal axis is the storage time (h), and the vertical axis is the amount of change in coercive force (KOe).
Is shown. The symbol G in the figure means a glass substrate. The initial value of the coercive force was 10 KOe. Fig. 3 shows an Al reflective film containing 5% Ti (curved
Line b) and the one containing 50% (curve c) at 280 ° C
The result when saved is shown. Anti-Ti-free
The change in coercive force is smaller than that of the coating (curve a)
Is understood. In addition, FIG. 4 shows that Ti is contained in the SiO ₂ transparent thin film .
Containing 5% and 50% (almost the same
Since one result was obtained, it is shown collectively as a curve e),
Also , 5% of Dy is also contained in the SiO ₂ transparent thin film.
And those containing 50% (Also in this case, almost the same
Since the result of is obtained, it is shown collectively as a curve f)
Shows how the coercive force changes when stored at 00 ° C
It SiO containing both Ti and Dy
Change in coercive force compared to transparent thin film (curve d) with only ₂
It turns out that is small.

In the above description of the embodiments, the present invention is applied to an element having a reflective film structure, but the present invention shows that the amorphous magnetic thin film is thick enough (about 1000Å) to form a thick film. The present invention can be applied to an element having the above structure, that is, an element utilizing only the Kerr effect.

[0012]

According to the present invention, due to the presence of Ti or rare earth metal (Gd, Tb, Dy, Ho, Y) contained in the transparent thin film adjacent to the amorphous magnetic thin film, the amorphous magnetic thin film is present. Since oxygen in the thin film can be greatly suppressed, the magnetic characteristics of this amorphous magnetic thin film can be stabilized, and the reliability of the device can be significantly improved.

[Brief description of drawings]

FIG. 1 is a side view of a magneto-optical storage element according to the present invention.

FIG. 2 is a side view of a conventional magneto-optical storage element.

FIG. 3 shows the change in coercive force when the Al reflection film contains Ti.
It is a figure which shows the conversion characteristic.

FIG. 4 is a diagram showing characteristics of the magneto-optical storage element of the present invention.
It

[Explanation of symbols]

 1 Transparent Substrate 2 Transparent Thin Film 3 Amorphous Magnetic Thin Film 4 Transparent Thin Film 5 Reflective Film 6 Reflective Film Containing Oxidizing Substance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Ota, 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Sharp Corporation (72) Hideka Yamaoka, 22-22 Nagaike-cho, Abeno-ku, Osaka City, Osaka Prefecture Inside the company

Claims (1)

[Claims] 1. A magneto-optical storage element comprising a transparent substrate on which an amorphous magnetic thin film made of a rare earth / transition metal alloy having an easy axis of magnetization in a direction perpendicular to the film surface is formed. A magneto-optical storage element comprising a transparent thin film adjacent to a body thin film, wherein the transparent thin film contains at least one of Ti and a rare earth metal.