JPS59108304A - Optical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium, whose thetaK is large and S/N ratio is excellent, by including one or more kinds of elements in an I A group and a IIA group into a group into a thin amorphous alloy film, which has an easy magnetizing axis in the vertical direction with respect to the film surface. CONSTITUTION:In a thin amorphous alloy film, which has an easy magnetizing axis in the vertical direction with respect to the film surface, one or more kinds of Li, Na, K, Rb, Cs, Fe, Be, Mg, Ca, Sr, Ba and Ra are included. Said alloy has a composition expressed by, e.g., a general formula (RXT1-X)1-YMY; where R is one or more kinds of Gd, Tb and Dy; T is one or more kinds of Co, Fe and Ni; M is one or more kinds of elements in said I A group and a II A group; X is in 0.1<=X<=0.4; and Y is in 0.01<=Y<=0.4. Said thin film is formed by a sputtering apparatus, a vacuum evaporation apparatus, an ion plating apparatus and other electroless plating method.

Description

[Detailed Description of the Invention] The present invention is based on the main components of rare earth elements and iron group elements →1.
The present invention relates to a magneto-optical recording medium that has a high-quality magnetic thin film and has an axis of easy magnetization in the film surface and in the direction of the aromatic stone.

Conventionally, partially or entirely amorphous magnetic thin films containing rare earth elements and iron group elements such as Fe, Co, and Ni as main components have an axis of easy magnetization in a direction perpendicular to the film surface. It is possible to create reversed magnetization in the form of a small spot (pit) with a diameter of about 1 μm in the opposite direction on the film surface where the S or N pole is fully magnetized. Compounds and alloys with a Curie point (Tc) or compensation temperature close to room temperature can be used as a magnetic memory medium that converts digital signals into digital signals. By using this effect, it is possible to create inverted magnetic domains of any size and shape at any position.By utilizing this, it is possible to record information, and it can be used as a magneto-optical memory medium in the form of disks, tapes, and sorts. It is becoming possible to use this method, and methods using the magnetic Kerr effect and Faraday effect are being used as readout methods.

Conventionally, the easy magnetization axis is perpendicular to the film surface, and information is written using a light beam.

MnB1 is a polycrystalline magnetic film alloy that can be read out.
．． Mn0uBi, AtCo, 0oOr, G as single crystal
d Engineering G, TbFe0. YGaIG, BiSmErGaI
G, and Ga0o, TbFe as amorphous.

DyFe, GdFeB1. GdTbFe, TbDyFe
Among these, amorphous magnetic film alloys are known to be good materials.

However, the above-mentioned amorphous magnetic film alloy has good writing sensitivity, low medium noise, and can stably produce a large area with perpendicular magnetic anisotropy.Also, the magnetic properties are suitably good, but the read performance (S/ The Kerr rotation angle (θ
k) is small, so the S/N ratio is small,
It has a public reputation that it is difficult to use it as a magneto-optical recording medium.

The present invention improves the above-mentioned conventional drawbacks and increases θk and t.
The object of the present invention is to provide a magneto-optical recording medium with an excellent S/N ratio.

The magneto-optical recording medium of the present invention has magnetic anisotropy with the magnetic easy axis in most directions perpendicular to the film surface, and has a magnetic anisotropy with a single Gyuri point (T c ) and a compensation temperature (T :;
; ) is close to room temperature, 50°C to 200°C, and is a thin film that is mostly in an amorphous state.

And conventionally, G(1,Tb) of rare earth element (R).

The above amorphous alloys of Dy, Fe, and COD have a magneto-optical effect.

Since T(1!, TCompt) is relatively good, it has attracted attention as a magneto-optical recording medium, and research is progressing.

However, in order to obtain a more excellent recording medium, it is necessary to increase θk. This is because reading performance (s/N ratio) improves by increasing θk. In other words, θ
If k is large, T c and T compt.

A medium whose magnetic properties are the same or better than conventional media is needed. In order to increase gold in θ, we have used Or, Ni, Bi, Ou, Ag, and Au.

Improvements have been attempted by adding Sn and co-4.

In the present invention, Li and Na are added as additive elements that increase θk and do not substantially deteriorate other properties such as T c , T compt and magnetic properties.
.

K, Rb, Os, Fr IA group, Be, Mg, Oa.

The reason is that he invented the IIA group of Sr, Ba, and Ra.

Moreover, as these 4-t, R, Be, Y, La, Oe, Pr, Nrl, Pm, Sm, other than G6-, Tb, Dy,
Fiu.

It was confirmed that Ho, Br, Tm, Yb, and Lu were similarly effective.

The present invention will be explained in detail below.

R (=Gd, Tb, Dy) and T (=Oo, F
e) amorphous alloy film Rx T1-x has traditionally been 0
It is widely known that 1≦X≦0.4. (For example, patent application No. 55-30251.55-170259.55
-57547 50-107107 51-255
3451-25534 etc.) and these are T O,
'rcompt is 50°C to 200°C, and suitable magnetic properties (Me.

nc, Ku), and is a medium with a perpendicular easy axis of magnetization. These are sputtering equipment, vacuum evaporation*V,
Neck, ion blating equipment, etc. 5 - Manufactured by many electroless plating methods. Generally, the target is manufactured by a melting method, a powder solidification method, or a method based on the area ratio of R and T. Then, a film of about 50 μm to several μm is formed on a silicon wafer, glass, puMh material, etc. as a substrate. We also produced IJi in the same manner. The results of measuring θk using a Kerr rotation angle measuring device are shown in FIGS. 1 and 2. In Figure 1, in the case of R=Gd, Tb, T=Oo, Fe, X is almost at the left point y=o in the range of 0.1≦X≦04.
is the value of θ at . and M=: Be, Oa, Ba.

For Na, Li, and Ni, Y increases between 0.01≦Y≦0.40. It seems that the effect is not very good beyond that.

This result is also the same for the other elements R, T, and M of the present invention. Moreover, compared to conventional media, there was almost no change in other properties, but the magnetic properties such as Hc were actually improved.

Also in Figure @2, M=Mg, Sr, Ra, Rb.

All examples of Os + F r were shown, and the result was 6- as in the case of FIG. In particular, Be, Ca, Mg, Sr, etc. seem to have a great effect. Although these figures are representative results, many combinations of R, T, and M of the present invention-14-
Similar results were obtained in . Furthermore, M of the present invention is also effective for polycrystalline films and crystalline films.

The magneto-optical recording medium of the present invention described above performs reading using the Kerr effect or the Faraday effect. However, writing uses a light beam such as a laser beam and utilizes its photothermal magnetic effect.

In this way, it becomes a rewritable memory that can be used as a beam addressable memory. Since θ is large, the EE/N can be widely applied as a rewritable memory for μ5it5 files, computers, audio, and video.

Writing, reading, erasing, etc. are performed using Ar.

Hθ-Ne and semiconductor lasers (e.g. Ga5A2.
AG, etc.).

[Brief explanation of the drawing]

Figure 1 shows (Rx T1-x) I-Y MY,
R=()d, Tb, T=Oo,
Fe, 0.15 M=Be for the composition of X≦0.4,
C! In addition to a, Ba, Na, Li, and Kffi, the relationship between the Kerr rotation angle θ and the atomic ratio Y is shown. Fig. 2 U (Rx T 1-x) 1-Y MY
In, R=Ga, Dy, Tb, T=OO, Fe
, M=Mg, Sr, Ra for the composition α1≦X≦0.4
, Rb, Os. The relationship between the Kerr rotation angle θ and the reduction ratio Y when Fr't=is applied is shown. Therefore −E (,)'/θ (.) River θ

Claims (3)

[Claims] (1) In an amorphous alloy having an axis of easy magnetization in a direction perpendicular to the film surface, Li, Na, Rb, Os, and Fr. A magnetic recording medium characterized by containing one or more of Be, Mg, Oa, Sr, Ba, and Ra. (2) General formula of alloy (RX T1-1) 1-Y MY
(R7 is one or more of Gd, Tb, and Dy. Also, T
is one or more of Co, Fe, and Ni. M (or one or more elements as described in claim 1. Therefore, X (rio, 1≦X≦0.4.Yldo, 0
1≦Y≦04. ) The thin-film magneto-optical recording medium according to claim 1, having a composition represented by: (3) Ri(1: Gd, Tb, Dy, sc, Y,
La, Oe. Pr, , Nd, Pm, Sm, Eu, Ha, Er, Tm,
Yb. 3. The thin film magneto-optical recording medium according to claim 2, wherein Lu is one or more types.