JPS63311643A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent initial characteristics and reliability and to relieve the restrictions on sputtering conditions by providing a magneto-optical recording layer consisting of a specific alloy. CONSTITUTION:The magneto-optical recording medium which executes recording, reproducing and erasing by projecting light on the amorphous magneto-optical recording layer which has the direction of magnetization perpendicular to the film plane and takes two values of either upward or downward is provided with the magneto-optical recording layer consisting of the alloy which is expressed by the general formula (LRxHR1-x)yA1-y-zBz, where 0<x<0.5, 0.1<y<0.5, 0<z<0.01, and LR is >=1 kinds among Y, La, Ce, Pr, Nd, and Sm, HR is >=1 kinds among Gd, Tb and Dy, A is >=1 kinds among Fe, Co and Ni, and B is >=1 kinds among Ti, Zr, Hf, Si, Ge, Pb. The magneto-optical recording medium which has the excellent initial characteristics and long-period reliability and is easy to produce is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the composition of a magneto-optical recording layer of a magneto-optical recording medium.

(Prior art) Research on magneto-optical memory is said to have started in 1957, when recording was performed on an MnB11 film using a hot pen, and the written magnetic domain was observed using the magneto-optic effect. Since then, stimulated by the development of lasers, intensive research has been carried out mainly on MnB1-based materials, but because the laser light source and peripheral technology were still immature, practical application was not achieved.

After that, advances in optical information processing related technology in the 1970s, as typified by amorphous rare earth transition metal alloy thin films,
As research into new magnetic thin film materials progresses, G d Fe
1T b Fe % D y −F e SG
Alloy thin films such as d-Co have been developed. These materials generally have the following characteristics.

Magneto-optical recording media for compensation point recording, such as G d -F e s G d -Co, have a larger Kerr rotation angle and superior optical reproduction characteristics compared to magneto-optical recording media for Curie single point recording, but have low coercive force. is small (several hundred Oersteds), 1μ
It is not possible to stably obtain small bits with a diameter of m. Also, Tb-
On the contrary, magneto-optical recording media for Curie single point recording such as Fe1Dy-Fe have a large coercive force (several kilo Oersteds) and
Although it is possible to stably obtain minute bits on the order of μm, the Kerr rotation angle is small and the optical reproduction characteristics are not very good.

In order to compensate for the drawbacks of these binary alloy thin films, the direction of diversification was suggested, and
358. Or Telegraph Research Fund, 02M80-44 (1
980) 31 etc.

[Problem that the invention seeks to solve]

However, the conventional technology focuses only on the initial magnetic properties of the magneto-optical distribution sB, such as the Kerr rotation angle, the primary temperature, and the reflectance.
There is no description of reliability such as environmental resistance or repeated recording/playback characteristics, workability during manufacturing, etc.

Therefore, the present invention is intended to solve such problems, and its purpose is to have excellent initial characteristics and long-term reliability,
The object of the present invention is to provide a magneto-optical recording medium that is easy to manufacture.

[Means for solving problems]

In the magneto-optical recording medium of the present invention, an amorphous magneto-optical recording layer in which the direction of magnetization is perpendicular to the film surface and has a binary value of upward or downward is irradiated with light to perform recording and erasing. In magnetic recording media, the general formula of the alloy is (LRxl-IRI-x
)yA, -y--BZ, 0<x<0.5 Q, 1<y<0.5 0<z<0.01 LR is 7% Las Ces PrlNd15m is one or more types, HR is Gd, Tbs Dy is one or more types, A is F
e s Co , N 1 is one or more types, B is T js
It is characterized by having a magneto-optical recording layer consisting of one or more types of Zrs Hft Sis Gez Pb.

[Example 1] FIG. 1 is a sectional view showing the structure of a magneto-optical recording medium employed in the present invention to check the characteristics of the magneto-optical recording medium.

1 and 5 are substrates, which are usually made of glass or translucent plastic (polycarbonate, epoxy, polymethyl methacrylate, amorphous polyolefin, etc.), and polycarbonate was used here. '2 is a protective layer, which is a light-transmitting compound film (oxide, nitride, sulfide, etc., such as Afl-os, si, etc.).

s, A I2 N SS 1 s N a , Z n
S, etc.), and here a nitride film with Aρ:5i=3 near was used. 3 is a magneto-optical recording layer, and 4 is a contact 1w layer.

For the adhesive layer in step 4, any translucent adhesive such as ultraviolet curing resin or thermosetting resin can be used, but here H
DDA (hexanediol diacrylate), TM
PTA ()limethylolpropane triacrylate)
An ultraviolet curable resin containing a 7:3 ratio of 7:3 was used.

[Example 2] A magneto-optical recording medium was prepared in which a magneto-optical distribution layer and a protective layer were formed by sputtering. The structure is shown in Figure 1, and the composition of the magneto-optical recording layer is (Ces, eiPre, *s
DY Yu,,). ,.

a (Fe*, sCO*, a) 0. Assuming yA-xBx, the component of B and the value of Z are shown in the m1 table.

Table 1 Here, S-1 to 5-22 are samples belonging to the scope of the present invention, and 5-23 to 5-31 are samples of comparative examples that are outside the scope of the present invention.

Table 2 shows the CNR of the sample and 70"CX90
Reliability under %RH environment (BER is 5X1 from initial value)
0-'time until increase).

As is clear from Table 2, the sample of the present invention has a CNR higher than that of the comparative example by 2 to 3 dB, and also achieved 3 dB in the reliability test.
It has more than twice the durability.

(Example 3) A magneto-optical recording medium was prepared in the same manner as in Example 2. The composition of the magneto-optical recording layer was (Ys, t@Nd, , Gdl, , Tb).

1)1. ! 6 (Fe*, sCO*, sNi
@.

+,)1. @I-z-13z The components of B and the values of 2 are shown in Table 3.

Table 3 and Table 4 show the CNR of the sample and 70°C x 90
%Reliability under RH environment (BER is 5X10 from initial value)
−'time until increase).

As is clear from Table 4, the sample of the present invention had a high CNR of about 52 dB (and also showed good results in the reliability test for more than 2000 hours).

For comparison, (Y* -ts Nd* -+s Gd*, 6 Tb
−.

s) e, sa (Fe*, @CO*, 5Nie.

1)1. When a magneto-optical media using @& was similarly evaluated, the CNR was 49.1 to 49°9 dB, and the reliability test was 700 to 800 H.

[Example 4] A magneto-optical recording medium was prepared in the same manner as in Example 2, and the composition of the magneto-optical distribution DIiI was (C84, tSm@, +Tlbo-*)e, a (F
e*-5Nf*, *)*, 5-zBx and the component of B,
and Z values are shown in Table 5.

Table 5 Table 6 shows the CNR of the sample and the 70°CX90
%Reliability under RH environment (BER is 5810 from initial value)
−'time until increase).

Table 6 Here, U-1 to U-12 are samples belonging to the scope of the present invention, and U-13 to U-16 are samples of comparative examples that are outside the scope of the present invention.

As is clear from the table, the CNR of the sample of the present invention is 2 to 3 dB higher than that of the comparative example (and 3 dB higher in the reliability test).
It has more than twice the durability.

[Example 5] 5-17 in Example 2, T-8 in Example 3,
u-12 in Example 4 and Example 3 as a comparative example
Similarly, (Y,,,,Nd,,,,Gdl,,Tb@.

*) e, si (Fe*, sCO*, sNlm.

,). ,.

We created magneto-optical media using this technology and evaluated its repeated recording and replay characteristics.

900γpmt Erase power 4.5mW, Recording power 4m
The change in time (〒) corresponding to the recording pit length of a single frequency was investigated under the conditions of W and read power of 1.2 mW.

The results are shown in FIG.

Here 11 is 5-17.12 is T-8, 13 is U-12
, 14 correspond to the comparative example.

As is clear from the figure, by adding the element B, the repeated recording and reproducing characteristics were greatly improved, and this tendency was the same for other component systems other than the present example.

Furthermore, the composition system of the present invention has the advantage that during sputtering, the pre-sputtering time for the magneto-optical recording layer can be reduced to about one-fourth of the conventional method, which has a significant effect on speeding up the film-forming process. Ta.

〔Effect of the invention〕

As detailed above, according to the present invention, light is irradiated onto the amorphous magneto-optical recording layer whose magnetization direction is perpendicular to the film surface and has a binary value of either upward or downward, thereby performing recording, reproduction, and erasing. In the magneto-optical recording medium to be used, when the general formula of the alloy is (LRx HR+ -x) y Al--z Bz, 0<X<0.5 Q, f<y<0.5 0<z<0.01 LR is one or more YN La1Cet Prs Nd55m, HRltGd, Tb, Dy is 111 or more, A is F
e 1Co 1N i is one or more types, B is T I N
By using a magneto-optical recording layer consisting of ZrXHf, S1SGe, and Pb of ta or more, it is possible to obtain a magneto-optical medium that has excellent initial characteristics and reliability, and has less restrictions on sputtering conditions, and is suitable for external memory for computers, fly rings, etc. It can be applied to optical memories for various uses such as systems.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a magneto-optical recording medium according to an embodiment of the present invention. The m2 diagram is an evaluation diagram of repeated recording and reproducing characteristics in an example of the present invention. Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Tsutomu Mogami and 1 other person;,,,-7
;/, Yu Tomb board λ Weight 3 Marutoki Kaiki ↑ Turtle 4 Hirotsu 44 Kaya /IZ I go away 1-1ii state (IjQ) ¥ 2
mouth

Claims (1)

[Claims] (1) In magneto-optical recording media, in which recording, reproduction, and erasing are performed by irradiating light onto an amorphous magneto-optical recording layer whose magnetization direction is perpendicular to the film surface and has a binary value of upward or downward, alloy The general formula of (LR_xHR_1_-_x)_yA_1_-_y_z
When B_z is 0<x<0.5 0.1<y<0.5 0<z<0.01 LR is one or more of Y, La, Ce, Pr, Nd, and Sm,
HR is one or more of Gd, Tb, Dy, A is Fe, Co,
Ni is one or more kinds, B is Ti, Zr, Hf, Si, Ge,
A magneto-optical recording medium comprising a magneto-optical recording layer comprising one or more of Sm and Pb.