JPH02110842A - Magneto-optical recording medium and magneto-optical recording method - Google Patents

Abstract

PURPOSE:To improve C/N by specifying the components of a recording layer and incorporating >=2 kinds of metals or semimetals as well as oxygen and nitrogen into an intermediate layer. CONSTITUTION:The recording layer 3 in which the contents of Tb, Dy and Co expressed by atomic % are 20.5<=Tb+Dy<=31.0, 0.088<=Tb/(Tb+Dy)<=0.22, 6.0<=Co<=15.0 and the balance is substantially Fe is formed on a substrate 2 and the intermediate layer is formed between the substrate 2 and the recording layer 2, by which the magneto-optical recording medium is formed. The intermediate layer 4 of the above-mentioned recording medium contains >=2 kinds of the metals or semimetals as well as the oxygen and nitrogen. Since the recording medium has the intermediate layer having such prescribed compsn. the C/N is extremely high.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a magneto-optical recording medium such as a magneto-optical recording disk, which records and reproduces information using heat and light such as a laser beam, and a magneto-optical recording medium. The present invention relates to a magneto-optical recording method for performing magneto-optical recording.

<Prior Art> A rare earth element-transition metal amorphous magnetic thin film is used in the recording layer of a magneto-optical recording medium.

As rare earth elements, Gd, Tb, Dy, etc. are preferably used, as transition metals, Fe, Co, etc. are preferably used, and in particular, C/
Since the N ratio is high, GdDyFeCo, TbDyFe
A recording layer made of Co has been proposed.

For example, in Japanese Patent Application Laid-Open No. 60-83305, Fe-C
In the o-Dy system, a part of Dy is replaced with Tb or Gd, and examples thereof include (Fe++I, Cob)
7aTb6Gd+e (however, o<b≦0.4) is described. The effect is an improvement in the C/N ratio due to an increase in the Kerr rotation angle.

Furthermore, in Japanese Patent Application Laid-Open No. 60-9855, TbDyFe
Examples include CO3a, s
F e ae, sD y+x, aT b 9.2, CO
+ , oF e g2.5D y! , 7 T b 10
．． 2 is listed. The effect is an improvement in the S/N ratio due to the synergistic effect of the decrease in the magnetostriction value and the increase in the Kerr rotation angle.

Furthermore, in the example of JP-A-60-107751, (D yo, T b o, y
) (F8o,yCOo,s). 8, i.e.
D V s T b 14F e saCO24 is described.

The effect is an improvement in the S/N ratio due to a decrease in the Curie temperature and an increase in the Kerr rotation angle.

Furthermore, in JP-A-60-233810, (F e o, s COol) o, a (Tb
o, D310. s). and (F e .

COO,l)0.79 (T b o,s D 3'
o, s) o, a+, i.e. F 8tzCO respectively
a T b +oD 5' +o and F e 71C
Oa T b +o, sD y+o, s are described.

In addition to these, JP-A No. 60-98611, JP-A No. 59-
TbDyF3C0 is also disclosed in Japanese Patent No. 217249, and its effects include an increase in Kerr rotation angle, an improvement in saturation magnetization, and a decrease in Curie temperature.

However, in the composition range described in the above publication, C/
The improvement in the N ratio may be insufficient, or the magnetic field strength required during information recording/erasing becomes large.

In other words, a magnetic field is externally applied to a magneto-optical recording medium when recording and erasing information, and the magnetic field strength (hereinafter referred to as "Hext") required for these is determined by the composition described in each of the above-mentioned publications. However, since a relatively large magnetic field, for example, 3000 e or more is required, the magnetic field generating device becomes large in size, and therefore the recording/reproducing device for the magneto-optical recording medium also becomes large. Furthermore, in the recording layer having the above composition, the magnetic field strength necessary for erasing information is naturally high.

In addition, in recent years, magnetic field modulation recording, which performs recording using a modulated magnetic field while irradiating light with a constant intensity, has attracted attention due to the demand for the so-called override method, which erases information by overwriting information without providing an independent erasing process. However, in this case, since the recording layer described in each of the above-mentioned publications requires a large applied magnetic field strength, it is necessary to use a coil with a large inductance. High-speed recording is difficult because a coil with large inductance cannot shorten the magnetic field reversal time.

Therefore, the present inventors determined that the content expressed in atomic percent of Tb, Dy, and Co is 20.5≦Tb+Dy≦31.0 0.088≦Tb/(Tb+Dy)≦0.226.0≦
We have proposed a magneto-optical recording medium having a recording layer in which Co≦15.0 and the remainder is substantially Fe, and a magnetic field modulation type magneto-optical recording method that enables high-speed recording using this magneto-optical recording medium ( (Japanese Patent Application No. 63-77394) This magneto-optical recording medium is
/N ratio is high, and Hext can be kept low.

Since the recording layer of the magneto-optical recording medium described in Japanese Patent Application No. 63-77394 has a small Hext, a coil with small inductance can be used and high-speed recording is possible.
Furthermore, when a coil with a smaller inductance is used to perform high-speed recording, the distance between the coil and the recording layer must be made close.

However, a double-sided recording type magneto-optical recording medium is constructed by laminating a pair of substrates each having a recording layer with the recording layer on the inside, or even in a single-sided recording type, the recording layer is placed on the same substrate as the substrate. In a magneto-optical recording medium having a protective plate with a certain thickness, it is difficult to bring the coil and the recording layer close to each other due to the thickness of the substrate or the protective plate. For this reason, when using a coil with smaller inductance, for example, a coil with a thickness of 1 to 100 mm made of an organic material is coated on the recording layer.
It is preferable to use it as a single-sided recording type magneto-optical recording medium provided with a protective coat of μm. However, such a protective coat cannot be said to have sufficient corrosion resistance.

For this reason, the present inventors added a group 4A element, a group 5A element, a group 6A element, a group 8 element, a group 3B element, C, We have proposed a magneto-optical recording medium in which at least one element selected from St and P is added as an additive element (Japanese Patent Application No. 140764/1983). This addition improves the corrosion resistance of the recording layer.

In addition, the present inventors have developed a magneto-optical recording medium in which Ge and/or Sr are added as additive elements to the recording layer of the magneto-optical recording medium described in Japanese Patent Application No. 63-77394 and Japanese Patent Application No. 63-140764. We are proposing a medium (patent application 1986-
No. 142462) This magneto-optical recording medium exhibits extremely small changes in the sensitivity of the recording layer even after storage under high temperature and high humidity conditions or after repeated reproduction.

Furthermore, the present inventors have disclosed that
In the recording layer of the magneto-optical recording medium described in No. 62, Bi, Cu
has proposed a magneto-optical recording medium in which one or more elements selected from , Sn, and Pb are added as an additive element (Japanese Patent Application No. 143335/1982). This magneto-optical recording medium has a further improved C/N ratio.

<Problems to be Solved by the Invention> However, there are strict requirements for the C/N ratio of magneto-optical recording media, and a magneto-optical recording medium having an even higher C/N ratio is required.

The present invention provides a magneto-optical recording medium that can reduce the intensity of the magnetic field applied from the outside when recording and erasing information and has an extremely high C/N ratio, and a magneto-optical recording medium that enables high-speed recording using this magneto-optical recording medium. The purpose of the present invention is to provide a magnetic field modulation type magneto-optical recording method.

Means to solve problems〉 Such objects are achieved by the invention described below.

That is, the present invention has the following (1) to (9).

(1) The content expressed in atomic percent of Tb, Dy and Co is 20.5≦Tb+Dy≦31.0 0.088≦Tb/(Tb+Dy)≦0.226.0≦
A magneto-optical recording medium having a recording layer on a substrate in which Co≦15.0 and the remainder being substantially Fe, and an intermediate layer between the substrate and the recording layer, wherein the intermediate layer 1. A magneto-optical recording medium characterized in that the medium contains two or more metals or metalloids, oxygen and nitrogen.

(2) The magneto-optical recording medium according to (1) above, wherein the metal or metalloid is silicon and aluminum.

(3) The magneto-optical recording medium according to (1) or (2) above, wherein the intermediate layer contains one or more elements selected from Y, a lanthanide element, and an actinide element.

(4) A group 4A element, a group 5A element,
Group 6A elements, Group 8 elements, Group 3B elements, C, Si and P
A magneto-optical recording medium characterized in that at least one element selected from among these is added as an additive element.

(5) the Group 4A elements are Ti, Zr and Hf;
The 5A group elements are V, Nb and Ta, and the 6A
The group elements are Cr, Mo and W, and the group 8 element is N.
The magneto-optical recording medium according to (4) above, wherein the group 3B elements are B and Aβ.

(6) A magneto-optical recording medium characterized in that Ge and/or Sr are added as additional elements to the recording layer of the magneto-optical recording medium according to any one of (1) to 5) above.

(7) For the recording layer of the magneto-optical recording medium according to any one of (1) to 6), Bi, Cu, Sn and
A magneto-optical recording medium characterized in that one or more of the elements selected from b. is added as an additive element.

(8) The total content of the additive elements in the recording layer is 1 to
The magneto-optical recording medium according to any one of (4) to 7) above, wherein the content is 20 at%.

(9) A method for performing magneto-optical recording on the magneto-optical recording medium according to any one of (1) to 8) above, wherein the magneto-optical recording is performed by applying a modulated magnetic field while irradiating light. A magneto-optical recording method characterized by performing the following.

Hereinafter, the specific configuration of the present invention will be explained in detail.

FIG. 1 shows a preferred embodiment of the magneto-optical recording medium of the present invention.

The magneto-optical recording medium 1 shown in FIG. 1 has a protective layer 3, an intermediate layer 4, a recording layer 5, a protective layer 6, and a protective coat 7 on a substrate 2 in this order.

The intermediate layer 4 is provided to increase the Kerr rotation angle and improve the C/N ratio, and in the present invention contains two or more metals or metalloids, oxygen and nitrogen.

By containing these elements, the C/N ratio is improved and the corrosion resistance is also improved.

Examples of such two or more metals or metalloids include Si, Aβ, Ti, Zn, B, Y, lanthanide elements, actinide elements, and the like.

Among these, it is preferable to include Si and 412 as essential elements, and in particular, in addition to SL and AI2, Y
, lanthanide elements, and actinide elements.

In such an intermediate layer, silicon and aluminum are
Usually contained in the form of oxides and nitrides, forming an amorphous substance.

Furthermore, among one or more elements selected from yttrium, lanthanide elements, and actinide elements, it is particularly preferable that one or more of yttrium and lanthanide elements be contained.

By containing these, recording sensitivity and C/N ratio become better.

In particular, yttrium (Y), lanthanum (La),
Cerium (Ce) Praseodymium (Pr), Neodymium (Nd), Samarium (Sm) and Europium (E
When one or more elements selected from the group consisting of u) is contained, even more favorable results can be obtained. At this time,
This is because better results can be obtained not only in terms of recording and reproducing characteristics such as recording sensitivity and C/N ratio, but also in terms of durability, corrosion resistance, etc.

In addition, by including these elements in the target used for sputtering, a dense target can be obtained.
As a result, the cooling efficiency of the target is improved and radiant heat during sputtering is suppressed.

One or more of these, yttrium, rank-maid elements, and actinide elements (hereinafter referred to as R)
is contained in a mixture with the amorphous substance in the protective layer, but it may be contained in the form of either a single element or a compound.

When contained as a compound, it is usually preferably contained in the form of an oxide.

The compounds in the intermediate layer may deviate from the stoichiometric ratio in their composition.

By containing these elements and oxygen and nitrogen, in addition to improving the C/N ratio and corrosion resistance, the light transmittance of the intermediate layer is improved and the amount of reflected light is increased, so the servo signal strength is increased and stable. It is possible to perform various servo operations.

In this case, if even one of these elements is missing, such an effect will not be achieved.

In the present invention, the content of Si+N in the intermediate layer is preferably 20 to 95 at%, more preferably 20 to 84 at%.
t%.

If this value is less than the above range, the refractive index will be low and the enhancement effect will be reduced, as well as the corrosion resistance will be reduced.

If this value exceeds the above range, the membrane stress will increase, so
When the film forming apparatus is used many times, dust is generated in the vacuum chamber of the apparatus, and pinholes are formed in the intermediate layer. Furthermore, since the light transmittance decreases, the reflectance decreases, and the servo signal strength becomes low, making it difficult to perform stable servo.

Moreover, it is more preferable that Si+N is 20 to 65 at% from the viewpoint of light transmittance.

The content of SL is preferably 5 to 45 at%.

The content of Aff is preferably 1 to 33 at%. At this time, the film quality becomes stable and dense, and corrosion resistance improves.

The content of R is preferably 0.1 to 35 at%. If it is less than 0.1 at%, the above effects will not be achieved, and if it exceeds 35 at%, corrosion resistance will deteriorate.

The content of each element in the protective layer is Auger, ESC
A. It may be measured by SIMS or the like.

A more preferable combination of contents of each of these elements,
This is shown in (1) and (2) below.

(1) The content of Si+N is 20 to 95 at%, preferably 20 to 84 at%, more preferably 20 to 65 at%
%.

The content of Si is 5 to 45 at%, more preferably 5 to 3
8at.%.

The content of Afl is 1 to 20 at%, more preferably 2 to 20 at%.
It is 1oat%.

The content of R is 2 to 35 at%, more preferably 6 to 3
It is 5at%.

(2) The content of Si+N is 20 to 90 at%, preferably 20 to 84 at%, more preferably 20 to 65 at%
%.

The content of Si is 8 to 40 at%, more preferably 8 to 3
It is 6at%.

The content of Aj2 is 3 to 33 at%, more preferably 3 to 33 at%.
It is 25at%.

The content of R is 0.1 to 2 at%, more preferably 0.
1 at% or more and less than 2 at%, more preferably 0.2 to
It is 1.9at%.

Note that such an intermediate layer material is used on the recording layer (described later).
It can also be provided as a protective layer on the opposite side of the substrate and used in combination with the intermediate layer 4.

When used together, the compositions of the intermediate layer and the protective layer may be the same or different within the prescribed range of the present invention.

Such an intermediate layer can be formed by various vapor phase deposition methods, for example, sputtering methods such as multi-source sputtering method using targets with two or more different compositions or reactive sputtering method using oxygen, vapor deposition method, and ion blating method. law, plasma CV
D. Formed by photo-CVD or the like.

In particular, it is preferable to use a sputtering method using a sintered body containing each of the above elements as a target or a multi-source sputtering method using a plurality of targets.

The thickness of such an intermediate layer is 30 to 300 nm.
, particularly preferably from 50 to 200 nm.

Furthermore, when the film thickness is set to λ/4n (λ is the wavelength of the laser used and n is the refractive index of the intermediate layer), more favorable results are obtained in terms of the enhancement effect.

Furthermore, Ar, N*, etc. present in the film forming atmosphere may be included as impurities in the intermediate layer.

Others: Fe20s, CuO1CrzOa, Mn
Ox %Co 01Nip, As5es, etc. are 1.
It may be contained in an amount of about 0 wt% or less.

The protective layer 3 and the protective layer 6 are provided to improve the corrosion resistance of the recording layer 5, and at least one of them is
Preferably both are provided. These protective layers are preferably composed of inorganic thin films made of various oxides, carbides, nitrides, sulfides, or mixtures thereof. Further, as described above, the intermediate layer may be formed of the above-mentioned materials. The thickness of the protective layer is 30-300n
From the viewpoint of improving corrosion resistance, it is preferable that the thickness is about m.

Such a protective layer is preferably formed by various vapor phase deposition methods such as sputtering.

In the present invention, the recording layer 5 has the above composition.

The reason why the composition ranges of Tb, Dy and Co are limited as described above is as follows.

If Tb+Dy is less than the above range, the magnetic field sensitivity will decrease and Hext will need to be about 3000e or more, and H
c decreases, leading to a decrease in the C/N ratio.

When Tb+Dy exceeds the above range, magnetic field sensitivity decreases, Hext needs to be about 3000e or more, and Hc
This causes a decrease in the C/N ratio and also decreases reliability.

When Tb/(Tb+Dy) is less than the above range, He
xt becomes approximately 3000e or more, and the Curie point decreases, resulting in a decrease in thermal stability.

When rb/(Tb+Dy) exceeds the above range, Hext
is about 3000e or more.

In addition, 2.5≦Tb≦5.0 and 18.0≦Dy≦26
．． When it is 0, even better characteristics can be obtained, and especially Hext is reduced.

If co is less than the above range, the corrosion resistance of the recording layer will be insufficient and reliability will decrease. In addition, the Curie point is lowered and the thermal stability is lowered.

When co exceeds the above range, the C/N ratio decreases and Hex
t also increases.

The remainder after removing these elements is substantially Fe.

In the present invention, the following X group and Y group are added to the recording layer having such a configuration.
At least one element selected from Group 2 and Group 2 may be added.

Group X: at least one element selected from Group 4A elements, Group 5A elements, Group 6A elements, Group 8 elements, Group 3B elements, C, Si, and P.

In this case, the 4A group elements are Ti, Zr and Hf, the 5A group elements are V, Nb and Ta, and the 6A group elements are V, Nb and Ta.
Group A elements include Cr, Mo, and W, Group 8 elements include Ni and Pt, and Group 3B elements include B and A.
J2 is preferred.

Y group 2 Ge and/or Sr.

Group 2: one or more elements selected from Bi, Cu, Sn, and Pb.

By adding the above group X, the corrosion resistance of the recording layer is improved.

By adding the above Y group, the effect of stabilizing the amorphous state of the recording layer is realized.

In other words, changes in sensitivity of the recording layer (annealing effect) that occur when the recording layer is stored at high temperatures and under high temperature conditions are prevented. Furthermore, changes in sensitivity of the recording layer due to repeated reproduction are also prevented. Note that this effect can also be achieved by adding B and/or Si among the above-mentioned group X.

By adding the above two groups, the Kerr rotation angle increases,
C/N ratio improves. Note that this effect can also be achieved by adding Cr and/or Ni among the above-mentioned group X.

The content ratio of these additive elements in the recording layer, that is, the ratio of the content of the additive element to the total content of Tb, Dy, Go, Fe, and the additive element is 1 to 20 at%.
, particularly preferably 2 to 10 at%. When the content is within this range, each of the above effects will be extremely high.

Such a recording layer 5 is preferably formed by a vapor phase deposition method, particularly a sputtering method, and is usually in an amorphous state.

Further, the thickness of the recording layer 5 is usually about 10 to 11,000 nm.

The substrate 2 is made of glass or resin, especially acrylic resin,
It is preferably made of polycarbonate resin, epoxy resin, polyolefin resin, etc., and is transparent to recording light and reproduction light. Further, the thickness thereof is usually about 0.5 to 3 mm, and the external shape is selected to be disc-shaped or other depending on the purpose.

The protective coat 7 is provided to improve corrosion resistance, and is preferably made of various organic substances, but in particular, it is made of acrylic double bonds that can be cured by radiation such as electron beams and ultraviolet rays. A radiation-curable compound having
Preferably, it is constructed from radiation-cured material.

Moreover, it is preferable that the thickness of the protective coat 7 is usually about 1 to 100 μm.

The magneto-optical recording medium 1 composed of these layers can be made into a double-sided recording medium by bonding two sets of magneto-optical recording media 1 with the recording layer 5 on the inside. A protective plate can be attached to the media to create a single-sided recording medium.

However, since the distance between the magnetic head and the medium can be kept small and high-speed recording is possible, it is preferable to use a single-sided recording type medium without a protective plate.

In addition, when a protective plate is provided, it is usually sufficient to use the same material as the substrate 2, but it does not have to be transparent, and other materials can also be used. Further, any known adhesive may be used for adhesion, such as a hot melt adhesive, a thermosetting adhesive, an anaerobic adhesive, etc.

Next, the magneto-optical recording method of the present invention using the magneto-optical recording medium of the present invention described above will be explained.

The magneto-optical recording method of the present invention is a magnetic field modulation type recording method in which recording is performed by applying a modulated magnetic field while irradiating light.

Usually, the magnetic field is applied from the side of the substrate on which the recording layer is provided.
In the present invention, the magnetic head for applying a magnetic field may be either a normal non-contact type magnetic head or an air floating type floating head, but it is possible to reduce the distance between the magnetic head and the medium. It is preferable to use a floating magnetic head because it enables high-speed recording.

The distance between the magnetic head and the recording layer is approximately 0.5 mm for a normal non-contact type head, and 5 to 20 μm for a floating type head.
Therefore, in the present invention, a single-sided recording medium without a protective plate is usually used.

In the present invention, the magnetic field strength on the recording layer surface of the medium is 3000
It is preferably less than e, preferably less than 2500e, more preferably less than 2000e.

By setting the magnetic field strength within this range, a coil with small inductance can be used. Therefore, the magnetic field reversal time can be shortened, and high-speed recording of, for example, 5 MHz or more is possible.

Light is typically emitted from the opposite side of the magnetic field.

The recording power is usually about 1 to 10 mW, and the spot diameter of the light on the surface of the recording layer is usually about 0.5 to 3 μm.

<Example> Hereinafter, the present invention will be explained in further detail by giving specific examples of the present invention.

[Example 1] On a substrate 2 made of bisphenol A-based optical disk grade polycarbonate resin with a diameter of 130 mm and a thickness of 1.2 mm, a protective layer 3 made of glass was deposited to a layer thickness of 40 nm by high-frequency magnetron sputtering. On this protective layer 3, an intermediate layer 4 having various compositions shown in Table 1 below was formed by a sputtering method, and in some cases a multi-source sputtering method. Note that the composition was measured by Auger spectroscopy.
Further, the film thickness was the optimum film thickness for enhancement (80 to 150 nm) calculated using E/4 for each sample.

Next, a recording layer 5 having a composition shown in Table 2 below was formed on the intermediate layer N4 by sputtering to a thickness of 80 nm. Note that the content ratio (at%) of Tb, D, y, and Co is T
This is the value when the total content of b, Dy, Co and Fe is set to 100. In addition, the content ratio (at
%) is a value when the total content of Tb%Dy, co, Fe and additional elements is set to 100.

Further, a protective layer 6 having the same composition as the protective layer 3 was formed on the recording layer 5 to a thickness of 1100 nm by high-frequency magnetron sputtering, and a protective coat 7 was formed on this protective layer 6.
The protective coat 7 is formed by applying a coating composition containing a polyfunctional oligoester acrylate and a photosensitizer onto the protective layer 6 using a spinner coat, and then cross-linking and curing it by irradiating it with ultraviolet rays for 15 seconds. Layered. The thickness of the protective coat 7 was 5 μm.

In this way, magneto-optical recording medium samples having intermediate layers and recording layers of various compositions were obtained.

Note that sample No. 9 was a comparative sample in which the intermediate layer 4 was not provided.

The following measurements were performed on the above sample.

(1) C/N ratio linear velocity 4. Om/sec frequency], MHz recording power (830 nm) 2.0 to 6.0 mW reproducing power (830 nm) 1.0 mW RB W 30 kHz V B W 100 Hz. The magnetic field strength during recording was 3000
It was set as e.

(2) Reflectance Reflectance at a wavelength of 830 nm at a flat portion was measured using a spectrophotometer.

(3) Corrosion resistance Initial pit error rate (BER) and 80℃/80%
The BER after storage at RH for 1000 hours was measured, and the amount of increase (ΔBER) was determined. The evaluation shown in Table 2 is
It is as follows.

0: No change ○: Increase amount is less than double △: Increase amount is greater than 2 times and less than 5 times X: Increase amount is greater than 5 times (4) Hext Among the following ■ and ■, the larger one was designated as Hext.

■ Recording is performed while increasing the applied magnetic field strength, and C
/Magnetic field strength when the N ratio reaches a certain value ■For the signal recorded with the applied magnetic field strength of 3000e at the optimum recording power, the same (erasing is performed by changing the applied magnetic field at the optimum recording power, and no unerased remains) Magnetic field strength when it becomes 1 dB or less (5) Coercive force (Hc) (6) Curie point (Tc) The results are shown in Table 2.

[Example 2] For each magneto-optical recording medium sample produced in Example 1,
Override recording (erasing by overwriting without providing an independent erasing process) was performed by magnetic field modulation, and the C/N ratio of each sample after recording was measured.

In magnetic field modulation recording, a 500 kHz square wave alternating magnetic field is applied to the recording layer surface using a small coil installed on the recording layer layer side of the substrate while irradiating a constant intensity laser beam from the side opposite to the recording layer layer surface of the substrate. This was done by doing this. The distance between the recording layer surface and the small coil was 0.2 mm, the magnetic field strength at the recording layer surface was 2500 e, and the linear velocity was 4.0 m/s.

In addition, when the distance between the recording layer surface and the small coil was set to 0.1 mm in order to increase the magnetic field strength on the recording layer surface, the small coil came into contact with the protective coat 7 due to deflection and warpage of the substrate, making recording impossible. Met.

Such magnetic field modulation recording was performed 10 times on the same track.

The C/N ratio is the same as in Example 1, with a reproduction power of 1.0 mW.
It was regenerated and measured.

A case where a C/N ratio of 45 dB or more was obtained was evaluated as O, and a case where the C/N ratio was less than 45 dB was evaluated as X.

The results are shown in Table 2. Note that Table 1 shows the composition of the intermediate layer of each sample shown in Table 2.

Table 1 middle class No.

t Intermediate layer composition (at%) AA ON R 3L+N I I 1, aI I a 12 M 4 Y+S1m18 [Example 3] Using each sample prepared in Example 1, the reproduction power 1
．． A continuous reproduction test was conducted at 5 mW.

For sample No. 106, the C/N ratio began to deteriorate after approximately 500 continuous playbacks, but for the other samples, no deterioration in the C/N ratio was observed even after 1000 or more continuous playbacks. .

[Example 4] Samples were prepared in which one or more of the above-mentioned additive elements X group, 7 group, and 7 group were added to the recording layers of sample Nos. 2 to 8 above, and the same corrosion resistance measurements and C/ The N ratio was measured.

In addition, the rate of change in sensitivity after storage for 1000 hours at 80° C. and 80% RH and the rate of change in sensitivity after repeated playback were also measured.

Corrosion resistance was further improved when the additive element included an element selected from Group X.

Furthermore, when the additive element included an element selected from the Y group, the rate of change in sensitivity was extremely small. In addition, also by adding B and/or SL among the above-mentioned group X.

This effect was achieved.

When the additive element included an element selected from the above two groups, the C/N ratio was further improved.

Note that this effect was also achieved by adding Cr and/or Ni among the above-mentioned group X.

The effects of the present invention are clear from the results of the above examples.

That is, the sample of the present invention has an extremely high C/N ratio. It also has high reflectance (and high corrosion resistance).

Moreover, the Hext is low at 2500e or less (Hc is high, and the Tc is higher than 100°C, so the thermal stability is high.

Further, when override recording was performed by magnetic field modulation at a magnetic field strength of 2500e on the recording layer surface, the sample of the present invention showed a good C/N ratio even after overriding, indicating that erasing was performed well by overriding.

Effect> In a magneto-optical recording medium, information is recorded by raising the temperature of a recording layer having a predetermined composition to around the Curie point by irradiation with laser light or the like, and applying a magnetic field from the outside at this time.

Information is recorded using optical modulation recording, which records using modulated light while applying a magnetic field of a certain intensity, or magnetic field modulation recording, which records using a modulated magnetic field while applying light of a certain intensity. Ru.

Information on a magneto-optical recording medium can be erased by externally applying Hc to the recording layer.
Either by the bulk erase method, which erases by applying a magnetic field similar to the one described above, or by raising the temperature of the recording layer by irradiating it with laser light, etc., an external magnetic field of the strength necessary to reverse the magnetization of the recording layer is applied. Apply it.

Further, when recording is performed by magnetic field modulation, recording and erasing can be performed by a so-called override method in which erasing is performed by overwriting information without providing an independent erasing process.

<Effects of the Invention> Since the magneto-optical recording medium of the present invention has an intermediate layer having a predetermined composition, the C/N ratio is extremely high.

Further, the magneto-optical recording medium of the present invention can suppress the intensity (Hext) of the magnetic field applied from the outside when recording and erasing information. Therefore, according to the present invention, the magneto-optical recording medium The recording/playback device can be downsized.

Furthermore, according to the magneto-optical recording method of the present invention in which magnetic field modulation recording is performed using the magneto-optical recording medium of the present invention, Hext can be kept low (suppressed), so a coil with small inductance can be used, and magnetic field reversal is possible. It is possible to perform high-speed recording in a short amount of time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a preferred embodiment of the magneto-optical recording medium of the present invention. Explanation of symbols 1... Magneto-optical recording medium, 2... Substrate, 3... Protective layer, 4... Intermediate layer, 5... Recording layer, 6... Protective layer, 7... Protective coat FIG, 1

Claims (1)

[Claims] (1) The content expressed in atomic % of Tb, Dy and Co is 20.5≦Tb+Dy≦31.0 0.088≦Tb/(Tb+Dy)≦0.226.0≦
A magneto-optical recording medium having a recording layer on a substrate in which Co≦15.0 and the remainder being substantially Fe, and an intermediate layer between the substrate and the recording layer, the intermediate layer 1. A magneto-optical recording medium characterized in that the medium contains two or more metals or metalloids, oxygen and nitrogen. (2) The magneto-optical recording medium according to claim 1, wherein the metal or metalloid is silicon and aluminum. (3) The magneto-optical recording medium according to claim 1 or 2, wherein the intermediate layer contains one or more elements selected from Y, a lanthanide element, and an actinide element. (4) For the recording layer of the magneto-optical recording medium according to any one of claims 1 to 3, a group 4A element, a group 5A element, a group 6A element, a group 8 element, a group 3B element, C, Si, and P are added. A magneto-optical recording medium characterized in that at least one element selected from among these is added as an additive element. (5) the Group 4A elements are Ti, Zr and Hf;
The 5A group elements are V, Nb and Ta, and the 6A
The group elements are Cr, Mo and W, and the group 8 element is N.
5. The magneto-optical recording medium according to claim 4, wherein the group 3B elements are B and Al. (6) A magneto-optical recording medium characterized in that Ge and/or Sr are added as additional elements to the recording layer of the magneto-optical recording medium according to any one of claims 1 to 5. (7) The recording layer of the magneto-optical recording medium according to any one of claims 1 to 6 is characterized in that one or more elements selected from Bi, Cu, Sn, and Pb are added as an additive element. magneto-optical recording medium. (8) The total content of the additive elements in the recording layer is 1 to
8. The magneto-optical recording medium according to claim 4, wherein the content is 20 at%. (9) A method for performing magneto-optical recording on the magneto-optical recording medium according to any one of claims 1 to 8, wherein the magneto-optical recording is performed by applying a modulated magnetic field while irradiating light. A magneto-optical recording method characterized by: