JPH0413250A - Magneto-optical recording element - Google Patents

Abstract

PURPOSE:To decrease the external magnetic field required for erasing and to decrease the coil current for erasing, etc., by forming an amorphous yttriums- SIALON (Y-SIALON) dielectric layer to 200 - 600 Angstrom thick. CONSTITUTION:The magneto-optical recording element consists of a transparent substrate 2, dielectric layer 4, magneto-optical recording layer 6, reflecting layer 10, and the dielectric layer comprising Y-Sialon is made 200 - 600 Angstrom thick. In this constitution, intensity of the external magnetic field required for erasing can be decreased without reducing the maximum C/N on recording. If the dielectric film is made >=700 Angstrom thick, the external magnetic field required for erasing increases. If the film is <200 Angstrom thick, the maximum C/N decreases, especially decreases in a higher magnetic field. This is because the Y-Sialon dielectric layer is made 200 - 600 Angstrom thick, and the erasing magnetic field for magneto-optical recording element using the amorphous Y-Sialon dielectric layer can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an improvement in a magneto-optical recording element using a yttrium-sialon dielectric layer.

[Prior Art] A magneto-optical recording element generally has a dielectric layer, a magneto-optical recording layer, and a reflective layer laminated on a transparent substrate. The dielectric layer C is for increasing the Kerr rotation angle by the Kerr enhancement effect, and is usually about 700 to 1200 A. It is also well known to use amorphous yttrium sialon as the dielectric layer;
Approximately 1,000 people have been robbed.

On the other hand, the inventors have discovered that the thickness of the dielectric layer affects the characteristics of the magneto-optical recording layer, changing the writing and erasing characteristics of the element.

[Problem of the Invention] An object of the present invention is to reduce the erasing magnetic field of a magneto-optical recording element using an amorphous yttrium-sialon dielectric layer.

[Structure of the Invention] A magneto-optical recording element of the present invention is a magneto-optical recording element in which a dielectric layer, a magneto-optical recording layer and a reflective layer are laminated on a transparent substrate. It is characterized by having 600 amorphous yttrium sialons.

The thickness of the yttrium-sialon dielectric layer is more preferably 300 to 550.

The thickness of the yttrium-sialon dielectric layer is 200 to 6
00 people, the strength of the external magnetic field necessary for erasing records decreases, and the maximum CZN ratio during recording hardly decreases. On the other hand, if the film thickness is 700A or more, the strength of the external magnetic field required for erasing increases. On the other hand, increase the film thickness to 20
If it is less than OA, the maximum C/N ratio will decrease and the C/N
The ratio decreases on the high field side. For this reason, the thickness of the yttrium-sialon dielectric layer is set to 200 to 600 layers.

Next, the film thickness is preferably 300 to 550 people. The characteristics during erasing hardly change when the film thickness is 200 to 600, but when the film thickness is less than 300, the C/N ratio decreases on the high magnetic field side. For this reason, the film thickness is preferably 300 to 550 people.

[Example] FIG. 1 shows the structure of a magneto-optical recording element of an example. In the figure, 2 is a glass substrate, 4 is an amorphous yttrium
This is the lower dielectric layer using Sialon. The thickness of the lower dielectric layer 4 is 200 to 600, more preferably 300 to 600.
The number of people will be 550. The composition of the amorphous yttrium sialon is Y, .Si, .Alc-0, .N.

It is expressed as 0　　　＜a＜0.5゜ 0.1<b<0.8゜ 0 <c<O-5゜ 0 <d<0.5゜ 0.1<e<0.7 a+b+c+d+e31 It is.

Reference numeral 6 denotes a magneto-optical recording layer, which is an amorphous thin film with a magnetization direction perpendicular to the substrate 2. Materials for such thin films include G
dDyFeTi, GdDyFe, GdTbFe, TbF
eCo, , DyFeCo, GdTbDyFe, GdTb
FeCo, TbDyFeCo, GdDyFeCo,
NdGdDyFe, NdDyFeCo, NdGdDyF
There are eCo etc. 8 is the upper dielectric layer, which uses the same amorphous indium sialon as the lower dielectric layer 4, but is made of SiO, SiO, CeO2, ZrO2, TiO2.
2°BizOx, ZnS, 5b2Sx, 5ixN4, etc. may also be used.

The upper dielectric layer 8 does not necessarily need to be provided, IO is a reflective layer, A1. Metals such as Ti, Cr, Cu, Ag, and Au and their low oxides are used.

The second diagram shows an element using a polycarbonate resin substrate 3. Polycarbonate can be replaced with any transparent resin such as epoxy, polyester, or acrylic. 4 is a lower dielectric layer with a film thickness of 200 to 600 layers, preferably 300 to 550 layers; 6 is a magneto-optical recording layer;
8 is an upper dielectric layer, IO is a reflective layer, and 12 is an ultraviolet curing resin protective layer. For the protective layer 12, an ultraviolet curing resin such as acrylic ester, epoxy, polyester, acrylic, or acrylic urethane is used. The protective layer 12 does not necessarily need to be provided.

The device of the example was manufactured as follows. When using the glass substrate 2, a slide glass was used. Board 2
, 3, the lower dielectric layer 4, the magneto-optical recording layer 6, the upper dielectric layer 8, and the reflective layer 10 were sputtered by magnetron sputtering.

The ultimate vacuum level during sputtering is 5XlO-'Torr.
, the distance between the substrate 2.3 and the target was 120 mm, the sputtering power was IKW, and the atmosphere was Ar.

Si3N as a target for the lower dielectric layer 4.

An amorphous yttrium sialon lower dielectric layer 4 having a thickness of 150 to 100 OA was formed using a sintered body having a molar ratio of :AhOs, Y, and Oj of 86:10:4. Next j: Gd
Targeting DyFeTi, amorphous GdDyFeT
A magneto-optical recording layer 6 (thickness: 20 OA) of a perpendicularly magnetized film was formed.Furthermore, an upper dielectric layer 8 (thickness: 300 OA) of amorphous yttrium sialon was formed, and a metal AI layer was formed on top of this. 400 people, laminated A1 low oxide to 15OA,
The reflective layer 10;

In the case of the device shown in Fig. 2, after sputtering is completed, a copolymer-based ultraviolet curable resin of urethane acrylate and acrylic acid ester is spin-coded and cured with ultraviolet rays.
A resin layer 12 with a thickness of 10 μm was formed.

3 to 7 show the influence of the film thickness of the lower dielectric layer 4. Measurement wavelength is 800nm, writing frequency is 3.7MH
z (270 nsec period).

FIG. 3 shows the relationship between the thickness of the lower dielectric layer 4 and MS-Hc. Ms is saturation magnetization, Hc is coercive force, and a slide glass substrate 2 was used as the substrate. This relationship holds true for the polycarbonate substrate 3 as well.

When the film thickness is 800 Å or less, MS-HC decreases monotonically. Note that symbols I to ■ in the figure represent samples, and the thickness of the lower dielectric layer 4 differs for each sample.

FIG. 4 shows the relationship between film thickness and C/N ratio. The substrate is a polycarbonate substrate 3. The smaller the MS-HC,
The external magnetic field required to erase records is small. For example, film thickness 95
For sample I with 0 people, the required external magnetic field is 2000e or more, but for sample ■ with a film thickness of 450 people and sample V with 250 people, the required external magnetic field is about 1500e, and for sample ■ with a film thickness of 150 people it is 1ooooe.
It is weak.

In Sample I and Sample ■, C when a high magnetic field was used for writing.
/N ratio decrease is small. However, in sample V, 2000e
When writing with the above conditions, a decrease in the C/N ratio was observed, and sample
In this case, the decrease in the C/N ratio on the high magnetic field side is more remarkable.

Figure 5 shows the strength of the external magnetic field necessary for erasing and the 3500e
The C/N ratio during writing is shown (polycarbonate substrate). For a film thickness of 250 to 550 mm, the erase magnetic field is almost constant. The drop in the C/N ratio during writing on the high magnetic field side is slight for 300 to 550 people, but the drop in the C/N ratio is steep at 300 A or less. Therefore, the film thickness was set to 30
If there are 0 to 550 people, C/ when writing on the high magnetic field side.
It is possible to suppress a decrease in the N ratio and reduce dependence on an external magnetic field during writing.

FIG. 6 shows the relationship between the thickness of the lower dielectric layer 4, the Kerr rotation angle θ, and the reflectance R. In addition, 800 people and 950 people in the figure
In the sample with a human thickness, the thickness of the upper dielectric layer 8 was 350 people. Further, the substrate is a glass slide.

FIG. 7 shows the relationship between the amount of jitter and the thickness of the lower dielectric layer 4 when magnetic field modulation recording is performed.

The substrate is polycarbonate. The coil currents used for writing were 200 mA and 400 mA, the writing frequency was 3.7 MHz (270 nsec period), and the amount of jitter was expressed by converting the standard deviation of the frequency during reproduction into n5eC units. The amount of jitter is small when the film thickness is 250 to 550 people, but the amount of jitter is large even when the thickness is 950 or 150 people.

[Effects of the Invention] In this invention, by setting the thickness of the amorphous yttrium-sialon dielectric layer to 200 to 600, the external magnetic field required during erasing is reduced, and the coil current during erasing is reduced. I can do it. Moreover, the maximum value of the C/N ratio hardly decreases.

Furthermore, the amount of jitter can be reduced when magnetic field modulation recording is performed.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of the magneto-optical recording element of the example. FIG. 3 is a characteristic diagram showing the relationship between the thickness of the lower dielectric layer and MS-HC, and FIG. 4 is a characteristic diagram showing the relationship between the recording magnetic field and the C/N ratio. Figures 5 to 7 are characteristic diagrams showing the influence of the thickness of the lower dielectric layer. Figure 5 shows the recording magnetic field required for erasing and the C/N ratio at 3500e, and Figure 6 shows the curve. The rotation angle and reflectance are shown, and FIG. 7 shows the amount of jitter. In the figure, 2 glass substrate, 3 polycarbonate substrate, 4
lower dielectric layer, 6 magneto-optical recording layer, 8 upper dielectric layer, IO reflective layer.

Claims (1)

[Claims] (1) In a magneto-optical recording element in which a dielectric layer, a magneto-optical recording layer and a reflective layer are laminated on a transparent substrate, the dielectric layer is made of amorphous yttrium sialon with a thickness of 200 to 600 Å. A magneto-optical recording element characterized by: