JPS59159510A - Magnetooptical recording medium - Google Patents

Abstract

PURPOSE:To set the coercive force of a recording medium to the magnitude to be readily handled by forming the composition of a magnetooptical recording medium alloy of TbY(Fe1-XCOX)1-Y, where X and Y satisfy the prescribed conditions. CONSTITUTION:A white plate glass is used as a base, and thin plates of Tb, Co are placed on a disc of Fe as a target. After the base and the target are set, it is evacuated in vacuum, an Ar gas is introduced. Electric power is applied to the target from a high frequency power source to form a film. This film is formed of Fe-Tb-Co amorphous magnetic alloy, and when the composition of the alloy is represented by TbY(Fe1-XCoS)1-Y, X and Y satisfy any one of four conditions 0<X<=0.375 and 0.1<=Y<=0.16+4X/57.7, 0.375<X<1 and 0.1<=Y<=0.2-0.064(X- 0.375), 0<X<=0.3 and 0.2+X/3<=Y<=0.4, 0.3<X<1 and 0.3<=Y<=0.4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical recording medium used for magneto-optical memo IJ-1 magnetic recording, display elements, etc. In particular, the present invention relates to a magneto-optical recording medium used for magneto-optical memo IJ-1 magnetic recording, display elements, etc. This invention relates to a magnetic thin film recording medium that can be released.

Conventionally, MnB1, MnCu are used as magneto-optical recording media.
Polycrystalline thin films such as B1, Gd, Co, G4Fe,
TbFe, DyFe.

Amorphous thin films such as GaTbFe and TbDyFe, G
Single crystal thin films such as IG are known. Among these thin films, the film-forming ability to produce a large-area thin film at a temperature near room temperature, the writing efficiency to write signals with small photothermal energy, and the ability to read written signals better than sZN. In consideration of read efficiency and the like, the amorphous thin film has recently been considered to be excellent as a magneto-optical recording medium.

However, in these amorphous thin films, the figure of merit corresponding to the readout efficiency for reading signals is smaller than that of polycrystalline thin films such as MnB1 and single crystalline thin films such as GIG.
, there is a drawback that a sufficient S/N ratio cannot be obtained.

A proposal to increase the magneto-optical constant of an amorphous thin film in order to read out a good S/N ratio is disclosed in Japanese Patent Application Laid-Open No. 56-12690.
No. 7 discloses an amorphous ternary alloy thin film such as GaTbFe. Furthermore, Abstractθof Th
e 1Qth engineering international CCo11
oquis on Magnetic Films an
d 5 surfaces (19B2.9.13-16)
There is an amorphous quinary alloy thin film such as TbFeCo as shown in 13a1. Table 1 shows the Kerr rotation angle, which is one of the magneto-optic constants of the conventional magneto-optic thin film.

Table 1 Material name Kerr rotation angle (button DyFθ o, 12TbFθ
0.18GdFe
O,24GdCo o,2Tb
DyFe o, 2゜GdDyF'e
O,24GdTdFe
o, 27TbO, 21(FeOJ5 C00
, 15) 0,79 0.52 (6628 measurement wavelengths) As can be seen from Table 1, the largest Kerr rotation angle is Tb.
0JI ("0,85 C00,15) 0.5 of 0.79
It goes without saying that the larger the magneto-optical constant, such as the Kerr rotation angle, the better in order to be able to read out the 87N ratio of 2 degrees.

On the other hand, since the alloys shown in Table 1 exhibit fesomagnetism, a compensating composition exists. Near this compensation composition region, the coercive force exhibits a very large value.

In general, the Kerr rotation angle, which has an effect on the S/N ratio, and the coercive force, which has an effect on the stability of the recorded magnetic flux, change independently depending on the alloy composition, so a composition with a large Kerr rotation angle does not necessarily have an appropriate size. It does not necessarily show coercive force. If the alloy composition has a very large coercive force even if the Kerr rotation angle is large, it is disadvantageous from a practical point of view as it requires a very large magnetic field to magnetize and demagnetize the recording medium. .

The object of the present invention is to have a sufficiently large magneto-optical constant and
It is an object of the present invention to provide a magneto-optical recording medium that can be read with a high ratio and has a coercive force that is easy to handle.

The present invention produces a ternary amorphous magnetic alloy of terbium, iron, and cobalt, and changes the composition of this alloy to TbY (F8.-x
COx), -1, then X and Y are the conditions, 0<
1-- X37.5 0.575 < X < 1 0.1 ≦Y ≦0.
2-0.0(S4(X-0,X175)O<X≦0.!
I and 0.20-≦Y≦0.40.3<X<1
The above object is achieved by a magneto-optical recording medium formed to satisfy any one of 0.3≦Y≦0.4.

Hereinafter, the present invention will be explained in detail using the drawings.

Figure 1 shows the magneto-optical constant quasi-TbFeC0 according to the present invention.
This figure shows the relationship between the composition and coercive force of an amorphous magnetic alloy. The curve 1 in the figure shows the compensation composition, 2, 2' indicates a coercive force of 4000 Oersted, and 6, 5' indicates a coercive force of 3.
000 Oersted, 4.4' indicates a coercive force of 2000 Oersted, 5,5' indicates a coercive force of 1000 Oersted, and 6.6' indicates a coercive force of 200 Oersted. For compositions near the compensation composition, the coercive force increases rapidly as the composition approaches the compensation composition. Media with compositions close to these compensation compositions require a very strong magnetic field during magnetization and demagnetization, and are also disadvantageous in terms of variation in characteristics and reproducibility during manufacture.

In general, in order to realize a magneto-optical recording medium that is easy to handle, the coercive force must be 400o Oersted or less.

In addition, as a composition that can provide sufficient magnetic anisotropy to orient the axis of easy magnetization in the direction perpendicular to the film surface, the atomic ratio of Fθ and Co is /HQ atom% to 9 Q atom%.
It is desirable that it exists in the range of .

Therefore, the composition having an appropriate coercive force is the area shown by diagonal lines in FIG. Approximating songs a2 and 2', the above regions have the following compositions: 0 < X < 0.375, 1 < Ys: o, t6 +
-X (1) 37.5 0.575 < X < 1 0.1≦Y≦0.2-
0.064(X-0,575) (2) 0 <X< 0
．． 3 and 0.2 10-<Y< 0.4
(3) 0.5 <X< 1 Katsu0.5 <Y<
0.4 It is expressed by four regions shown by the equation (4).

Examples of the present invention formed with compositions satisfying the above formula will be shown below.

(Example) 25 m x 76 y in high frequency sputtering equipment
A white glass plate with a size of m is used as a substrate, and 14 thin plates of Tb, 2 thin plates of Co, each with a size of 10 square x 10 and a thickness of 1M are placed on a Fe disk with a diameter of 12711I as a target. The distance between the board and target was 9
After setting the pressure to 0 Torr, the vacuum was evacuated until the pressure became 3×10 Torr or less. After this, 99.99
Ar gas with a purity of 9% was introduced to 6 x 10''-5 TOrr.The Ar flow rate at this time was 608 CCM.Electric power was applied to the high frequency power source target at a rate of 2 W/cIrL2 to perform #filming. .

(Sandals AI) The film with a thickness of 1500 A thus formed had an axis of easy magnetization in the direction perpendicular to the film surface, and was found to be amorphous as a result of X-ray diffraction. It was found that Co had a balance Fθ of 4.7 μ%. The Kerr rotation angle of this film is 0
．． 29°, and the coercive force was 1500 oersted.

Table 2 shows the results of a similar experiment conducted using sample A1, the target Tl), and the number of C0 thin plates.

Table 2 As described above, in the present invention, by regulating the amount of Tb in the Tb-Fe-Go 5-component amorphous magnetic alloy, a magneto-optical recording medium having a coercive force that is easy to handle can be obtained. It is desirable to obtain a magneto-optical recording medium with a high reading S/N ratio by appropriately selecting the atomic ratio of Fe and CO.

In the magneto-optical recording medium made of the Tb-Fe-Go quinary amorphous magnetic thin film of the present invention, when the combined atomic ratio of Fe and CO is 1Q Q atom%, the atomic ratio of CO increases. As the car rotation angle increases, Co
The Kerr rotation angle is maximum when the atomic ratio of Co is 50 atom%, and as the amount of Co is further increased, the Kerr rotation angle becomes smaller.

In order to enable readout with a sufficiently high S/N ratio, Co
The atomic ratio of must be in the range of 5 Q atom% to 7 Q atom%. Therefore, in the present invention, the composition of the alloy is within the range of formulas (1) to (4), and the atomic ratio of Fe and Co is 100'at.
When expressed as om%, the atomic ratio of Co is 3 Q atoI
By configuring it so that it exists in the range of r1% to 7 g Btom%, a magneto-optical recording medium having a high reading S/N ratio and a coercive force that is easy to handle can be obtained. Further, in the magneto-optical recording medium, when the combined atomic ratio of Fe and CO is 1100 atom%, the atomic ratio of Go is 4Q atom% to 6Q ILt.
O! If the Kerr rotation angle is configured so that it exists within the range of n%, the deviation of the Kerr rotation angle from the maximum value is only within about 6%, and it is easy to handle from a manufacturing perspective, where variations in characteristics, reproducibility, etc. must be considered. Exactly similar results were obtained.

As explained above, the present invention has the effect of increasing the coercive force of a conventional magneto-optical recording medium to a size that is easy to handle.

[Brief explanation of the drawing]

FIG. 1 shows a TbFeCo magneto-optical recording medium according to the present invention.
FIG. 3 is a diagram showing the relationship between the composition and coercive force of a quinary amorphous magnetic alloy. 1... Compensation composition 2.2'... Composition showing a coercive force of 4000 Aersted 6.6'... Composition showing a coercive force of 3000 Aersted 4.4'... Composition showing a coercive force of 2000 Aersted 5. 5'...Composition exhibiting a coercive force of 1000 Oersted 6.6'...Composition exhibiting a coercive force of 200 Oerstedll:e!

Claims (1)

[Claims] The composition of the ternary amorphous magnetic alloy of terbium, iron, and cobalt is T1) Y(Fe, -xCoX),
- When expressed as d, X and Y are conditions, 1) o<x
≦0.375 and 0.1≦Y≦o-16+ -g-T,
s x (2) 0.575 <X<1 and 0.1<Y≦
0.2-0.064(X-0,375)'(5)O<X
≦0.5 and 0.2+, -≦Y<:0.4(4)0
．． Any one of 3<X<l and 0.5≦Y≦0.4
A magneto-optical recording medium formed to satisfy two requirements.