JPS62128041A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To form a photomagnetic recording medium which has excellent quantity of magnetization, coercive force and anisotropy and permits high density recording by providing a magnetized film for photomagnetic recording repeatedly laminated with metallic layers and respective ultrathin film layers of transition metallic layers and specifying the thickness of the rare earth metallic layers and the compsn. as the entire part of the magnetized film for photomagnetic recording. CONSTITUTION:The magnetized film 4 for photomagnetic recording which is successively and repeatedly laminated with the rare earth metallic layers 2 consisting of >=1 kinds among Tb, Dy, and Gd and the transition metallic layers 3 consisting of >=1 kinds among Fe, Co, and Ni by vapor deposition and sputtering, etc. and has a vertical anisotropy is constituted on a substrate 1. The rare earth metallic layers 2 and the transition metallic layers 3 are respectively formed to the ultrasmall thickness of order of an atomic layer and particularly the thickness of the rare earth metallic layers 2 is selected at >=2Angstrom and <6Angstrom . All of Tb, Dy, and Dg of rare earth metals have a bout 3.5Angstrom atomic diameter and therefore the thickness of >=2Angstrom and <6Angstrom is approximately equiv. to 2 atomic layers or below or single atomic layer. The compsn. ratio of the rare earth metals and transition metals is specified to 10-40atom% rare earth metal and the balance transition metal as the whole of the recording layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium applied to, for example, a rewritable magneto-optical disk.

[I existing requirements of the invention]

The present invention provides a magnetized film for magneto-optical recording in which ultrathin layers of a metal layer and a transition metal layer are repeatedly laminated, and the thickness of the rare earth metal layer and the composition of the magnetized film for magneto-optical recording as a whole are determined. By specifying this, a magneto-optical recording medium with excellent magnetization, coercive force, and anisotropy, and which enables high-density recording, can be constructed.

[Conventional technology]

The present applicant has previously provided a magneto-optical recording medium having a structure in which rare earth metal layers and transition metal layers are alternately laminated (see Japanese Patent Application No. 59-217247). This magneto-optical recording medium is designed to improve the squareness ratio and coercive force Hc.

[Problem that the invention seeks to solve]

In the present invention, as described above, in a magneto-optical recording medium having a magnetized film for magneto-optical recording having a repeated laminated structure of a rare earth metal layer and a transition metal layer, the thickness of the rare earth metal layer and the overall rare earth metal and transition Based on the investigation that the composition ratio with metal has a large effect on magnetic properties, we aim to further improve the properties.

[Means for solving problems]

As shown in FIG.
a rare earth metal layer (2) consisting of one or more of Y and Gd;
A transition metal layer consisting of one or more of Fe, Co, and Ni (
Magneto-optical recording magnet I1w (4
1.

These rare earth metal N (2) and transition metal layer (3) are:
Each layer has an extremely thin thickness on the order of an atomic layer, and in particular, the thickness of the rare earth metal layer (2) is selected to be 2 Å or more and less than 6 Å.

Here, since the atomic diameter of the rare earth metals Tb, DV, and Gd is about 3.5 nm, a thickness of 2 Å or more and less than 6 nm corresponds to a diatomic layer or less or a monoatomic layer. It will be of a certain extent.

In addition, the composition ratio of rare earth metals and transition metals in the recording layer (
4), the total content of rare earth metals is 10 to 40 atomic %, and the remainder is transition metal. However, even if the composition is within this range, the compensation point composition is outside this range. For example, when Fe is used as the transition metal and the rare earth metal is Tb, the overall composition of the magnetized film (4) is 22~
23 atomic%, in the case of Gd or ay, this is 25~
At 26 atom%? ili (1 point.

[Effect]

When using the above-described magneto-optical recording medium according to the present invention, a magneto-optical recording medium can be obtained which has large magnetic anisotropy, a large amount of magnetization, and a high coercive force, and is therefore capable of high-density recording. this is,
Coupled with the repeated laminated structure of the rare earth metal layer (2) and the transition metal layer (3) according to the present invention, recording magnetization can be achieved by specifying the thickness of the rare earth metal layer (2) and further specifying the overall composition. In the film (4), in the thickness direction, a basic atomic pair configuration in which 2IIlil transition gold mud atoms are bonded to one rare earth metal atom is formed in just the right amount, that is, transition metal atoms are bonded to each other, or rare earth This seems to be due to the fact that the metal atoms are efficiently arranged in the film thickness direction with almost no bonding.

〔Example〕

The magneto-optical recording layer (4) of the magneto-optical recording medium according to the present invention can be formed by sputtering.

As shown in FIG. 2, this sputtering device may have a magnetron type configuration. In this case, a base (6) that rotates around an axis 0-0' is provided in a bell jar (not shown), and a base (11) constituting the intended magneto-optical recording medium is mounted on the bottom surface of the base (6), for example. Two sputtering sources (7) and (8) are placed facing the base (1) at equiangular intervals, that is, at an angular interval of 180°, about the axis 0-0'. Between these sputtering sources (7) and (8) and the base (6), that is, the base (1), there are sputtering positions for metal sputtered from the sputtering sources (7) and (8), respectively. The sputtering source (7) is made of a rare earth metal and has a target α (to), and the sputtering source (8) is a target α (11) made of a transition metal plate. It consists of
(12) and (13) each indicate a magnet.

For example, as shown in FIG. 3, the mask (9) has a ginkgo-shaped part facing the targets 00) and (11) that extends outward in the direction of a straight line X passing through the centers of these targets 00) and (11). windows (14) and (I5) are bored in the base body (14) and (I5), and when the base base (6) is stopped, the base body (1
For example, the rare earth metal from one target [alpha] is sputtered mainly onto one half of the target (11), and the transition metal from the other target (11) is mainly sputtered onto the other half.

Then, while rotating the base (6), DC sputtering is performed with targets QO) and (11) on the negative electrode side.

In this manner, while rotating the base (6), a laminated magnetic film (4) having a total thickness of 200 to 50,000 layers, for example, 1,000 layers is formed.

Example 1 Magnetization J for magneto-optical recording by a Tb-Fe magnetized film having a total composition of 19 at% Tb on a glass substrate (11)
l! ! (41 was formed.) This magnetized film (4) was formed using the sputtering apparatus described in FIGS. The rotation speed of the base (6) and therefore the base body (1) is set to 2Or,p
I went with ,m.

The sputtering currents for Tb target 0φ and Fe target (11) are 0.6 A and 2.5 A, respectively.
I gave it an A. At this time, the crystallization rate of Tb is approximately 1.5
person/sec, that of Fe is approximately 2.6 person/s
It was ec.

In this way, (rl) Tb-Fe demagnetization of the magneto-optical medium (4) is achieved by repeatedly forming the rare earth metal layer (2) made of Tb and the transition metal layer (3) made of Fe as explained in FIG.
It was confirmed that a periodic structure formed by layers was formed. This confirmation was performed by small-angle X-ray diffraction. Figure 4 is the X
This figure shows the measurement of the diffraction intensity with respect to the angle 2θ, where θ is the angle between the beam irradiation and the film surface, and in this case, Co-KeL
(wavelength λ = 1.79 people) was used.

According to Fig. 4, a diffraction peak occurs at 2θ = 8.4, and the pitch of the repetition period (that is, the pitch of the repetition period (that is, the pitch of the rare earth metal Tb1ii (21) and the transition metal Fe layer (3)) Therefore, it can be seen that the pitch P is 12.2 people.

Example 2 A magnetized film was formed by the same method as in Example 1, but Tb was selected to be 21 atomic % as a whole.

FIG. 5 shows the results of measuring the magnetic properties of the magneto-optical recording media according to Examples 1 and 2 by varying the thickness of the Tb metal layer. The dashed curve shows an overall Tb ratio of 19
When expressed as atomic %, the solid line curve is for 21 atomic %, curves 1 and 2 are the measurement results of the magnetic anisotropy coefficient, and curves MS1 and MS2 are the measurement results of the magnetization amount (curve). (C1 and HC2 indicate the measurement results of coercive force.

According to this, it can be seen that excellent magnetic properties are exhibited when the thickness of the Tb layer (2) is 2 to 6 layers.

Furthermore, the sputtering conditions were set to 0.6A for Tb and 1.85A for SFe, and the sputtering rate for Tb was set to 1.
．． 5 people/sec, Fe sputtering speed 2
．． 5 people/sec, each layer (2) and (3) 1 each
When the film thickness is formed in seconds, 3 seconds, and 6 seconds, that is, when the Tb layer (2) is 1.5 thick and the Fe layer (3) is 2.5 thick, the Tb layer (2) is 4.5 thick. In humans, Fe layer (3) is 7.5
For humans, the Tb layer (2) is 9 people and the Fe layer (3) is 15A.
The magnetization curves at the time are shown in FIG. 6, FIG. 7, and FIG. 8, respectively. Table 1 shows the saturation magnetization MS and coercive force He at this time.

This also reduces the thickness of T bJi (2) to less than 6 people 2
The example shown in FIG. 7, which corresponds to Å or more, has excellent Ms and Hc, and also shows a high squareness ratio.

Example 3 A glass substrate (11) with an overall composition of 20% Tb, 80% Fe-Co transition metal, and Fe
The ratio of Go and l1l (atomic ratio), that is, Tb2o
(Fe5sCo5) n.

A magnetized film was formed. In this case, as in Example 1, the same sputtering apparatus as described above was used.

In this case, a Tb target was used as the target aω, and a Pe5s Cos alloy target was used as the target (11). The sputtering conditions at this time were Tb
0.6A for Fe55Cos, 2 for Fe55Cos
．． 2A, and the rotation speed of the base (6) is 20r, p, m,
And so. The growth rate of Tb at this time is approximately 1.4 people/
sec+Feg5 That of Co5 is 2.6 people/sec. Tb2o (Fe5s C
o5) Similarly, for the +Io magnetized film (4), Co-
When small-angle X-ray diffraction was measured using kX-rays, the result was as shown in Figure 9, and since it had a peak at 2θ = 8°, it was determined that the Tb layer (2) and the Fe5s CoS layer (3) were repeatedly laminated. The periodic pitch P was found to be 12.9 people.

The overall composition of the above-mentioned Tb-FeCo magnetized film (4) is Tb
Fig. 1θ shows the results of measuring the saturation value MS, Kerr rotation angle θk, and Curie point Tc when expressed as -Fe1-y Coy and changing the value of y, that is, the amount of Co. In FIG. 10, the curves MSCO+ θkco and T CCO do not indicate their saturation magnetization MS, Kerr rotation angle θk, and Curie point Tc, respectively. According to this, there is a tendency for Mg and θk to increase with an increase in the amount of co, but since the Curie point Tc also increases, if the amount of co is too large, the recording power increases. Therefore, the amount of Co in the transition metal component is 1 to 3.
It is desirable to select 0 atomic %.

Example 4 A Gd-Fe magnetized film was produced on the glass substrate [1] using the same sputtering apparatus as described above.

In this case, Gd is used as the target αω of the sputtering device, Pe is used as the target (11), and Gd
The growth rate of Fe was approximately 1.5 people/sec, and that of Fe was approximately 2.6 people/sec. In this case, the pitch P of the repetition period between the Gd rare earth metal layer (2) and the Fe transition metal layer (3) was 12.5 as measured by small-angle X-ray diffraction.

Example 5 A Dy-Fe magnetized film was produced on a glass substrate (1) using the same sputtering apparatus as described above.

In this case, Dy was used as the target Q[I] of the sputtering device, and Fe was used as the target (11).

Regarding each of Examples 1.4 and 5 described above, Tb of each rare earth element is used as the composition of the entire magnetized film (4).

By changing the amount of Gd and oyO, each Curie point Tc
.

The measurement results of saturation magnetization MS and coercive force Hc are shown in FIG. In the same figure, the curves Hctb, Hcgd and Hcd
y indicates the measurement results of the coercive force Hc with respect to changes in the composition ratio of Tb, Gd and oy, respectively, Mstb, Msg
d and M sdy show the measurement results of saturation magnetization M g with respect to changes in the similar composition ratios of Tb, Gd, and Dy, respectively, and curves T c tb +T cgd and Tcdy show the results of measurement of the saturation magnetization M g with respect to changes in the similar composition ratios of Tb, Gd, and Dy, respectively. The measurement results of the Curie temperature Tc with respect to changes in are shown.

Example 6 A Gd-FeCo magnetized film was produced on a glass substrate (1) using the same sputtering apparatus as described above.

In this case, Gd was used as the target 00) of the sputtering device, and an Fe-Co alloy was used as the target (11).

Example 7 A GdTb-Fe magnetized film was produced on a glass substrate (1) using the same sputtering apparatus as described above.

In this case, the target α of the sputtering device is Gd2o, the target (11) is Fe.
was used.

Example 8 A GdTb-FeCo magnetized film was produced on a glass substrate (1) using the same sputtering apparatus as described above. In this case, a Gd2a Fbeo alloy was used as the target αω of the sputtering device, and a Fe55Cos alloy was used as the target (11).

Example 9 A TbDy FeCo magnetized film was produced on a glass substrate (1) using the same sputtering apparatus as described above. In this case, the target 01l of the sputtering device
Tb5o Dy5o alloy as ll, target (1
Ita using Fe5o Co5o as 1).

Each of these Examples 6 to 9 also had high Hc.

MS and Tc are shown.

〔Effect of the invention〕

As described above, according to the present invention, although the structure of the magnetized film is formed by repeatedly laminating the rare earth metal layer (2) and the transition metal layer (3), both layers (2) and (3) are formed on the atomic layer order. In particular, the rare earth metal layer (2) has a thin layer of 2 to 6 people, and the composition of the entire magnetized film has a rare earth metal of 10
By setting the composition to 40 atomic % and excluding the compensation point composition, it was possible to obtain a magneto-optical recording medium with excellent magnetic properties.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of an example of a magneto-optical recording medium according to the present invention, FIG. 2 is a configuration diagram of an example of a sputtering apparatus, FIG. 3 is a plan view of a mask thereof, and FIGS. 4 and 9 are FIG. 5 is a measurement curve diagram of the irradiation angle-intensity of small-angle X-ray diffraction of an example of the magneto-optical recording medium according to the present invention, FIG. 5 is a measurement curve diagram of the relationship between Tb film thickness and each magnetic property, and FIGS. 6 to 8 is a magnetization characteristic curve diagram, Figure 10 is a diagram showing the Co content and each characteristic, and Figure 11 is a diagram showing the Co content and each characteristic.
The figure is a diagram showing the relationship between the rare earth metal content and each characteristic. (11 is the substrate, (2) is the rare earth metal layer, (3) is the transition metal layer, and (4) is the magnetized film. Figure 3: Planar view of the /1 mask. % mlu'r”I
n 'l'J Fixed curve amFigure 5Figure 10Figure 11

Claims (1)

[Claims] The magnetic film for magneto-optical recording is formed by sequentially stacking a rare earth metal layer and a transition metal layer on a substrate, and the rare earth metal layer is selected to have a thickness of 2 Å or more and less than 6 Å, 1. A magneto-optical recording medium characterized in that the overall composition is comprised of 10 to 40 atomic % of rare earth metals, and the composition is selected to exclude a compensation point composition.