JPH02105352A - magneto-optical recording medium - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium that is capable of high-speed, high-density recording and is suitable for a magnetic field modulation method.

[Conventional technology]

Magneto-optical recording media utilize perpendicular magnetic recording and magneto-optical effects (Kerr effect, etc.), and like conventional optical recording media, they use laser light to record and reproduce information, so they have a large recording capacity. Can be overwritten. Furthermore, recording and reproduction can be performed without contact between the head and the medium, and it is not affected by dust, so it has excellent stability. For this reason, magneto-optical recording media are currently being actively researched, and are expected to be used for document information files, video/still image files, computer memory, etc., or to replace floppy disks and hard disks, and are expected to be commercialized in the near future. We have reached the point of welcoming

A transition metal (
Fe, Go) and rare earth metals (Tb, Dy, Gd, Ha
, Er, etc.) have been proposed. A magnetic alloy film made by combining one or more transition metals and one or more rare earth metals and fabricated on a substrate by sputtering or vapor deposition is an amorphous perpendicularly magnetized film (easily magnetized in the direction perpendicular to the film surface) near the compensation composition. It becomes a magnetized film with an axis) and can be applied to magneto-optical recording media.

On the other hand, optical modulation is currently the mainstream method for recording and erasing information on magneto-optical recording media. According to this optical modulation method, recording and erasing are performed by inputting a modulated information signal to a semiconductor laser, irradiating the laser pulse light onto the recording layer of the magneto-optical recording medium to heat it, and simultaneously recording or erasing on that part. This is done by applying an external magnetic field in the direction. In this method, if information has already been recorded, it is erased and then new information is recorded. Generally, there are two methods of erasing: one is to erase one sector at a time, and the other is to arrange two heads close together so that the two laser beams can be irradiated closely, and then use the preceding head to erase the data. . The former method requires waiting time for the recording layer after erasing.

In addition, the latter method requires the erasing and recording electromagnets or magnets to be placed close to each other, but there is a limit to how close these electromagnets or magnets can be placed due to their size or the influence of each other's magnetic fields. , this creates an area that is not erased. That is, as schematically shown in FIG.
Assuming that it is erased in area B and recorded in area B,
When the magneto-optical recording medium rotates once and returns to area A,
The erasing laser beam irradiates the next track or is turned off (if it is not turned off, the information in the area where information is recorded will be erased). Therefore, the area between AB becomes an area that cannot be erased.

For the reasons mentioned above, a magnetic field modulation method that can be overridden (superimposed) is attracting attention instead of an optical modulation method. This method uses a floating magnetic head 2 as shown in FIG.
It is excited by inputting an information signal modulated to 1, and at the same time irradiates the laser beam 22 continuously or in synchronization with the channel clock, and like current magnetic disks, overrides are possible, that is, erasing is not necessary. .

[Problem to be solved by the invention]

However, the prior art has the following problems.

From the standpoint of increasing the speed of information processing and replacing hard disks, etc., it is desirable that the recording speed on magneto-optical recording media be equal to or higher than that of hard disks, that recording can be performed at high density, and that it is compatible with an overridable magnetic field modulation method. It will be done. To achieve this, recording must be possible at a disk rotation speed of 360 rpm, a linear velocity of 22.6 m/s, a recording frequency of 10 MHz or more, a recording laser power (medium surface) of 10 mV or less, and a recording bit (recording magnetic domain) size of 1 tone or less, and a recording bit size of 1 tone or less. is required to have a sharp shape. However, none of the conventional magneto-optical recording media satisfies the above conditions, and it has been desired to realize a magneto-optical recording medium with further improved characteristics.

In view of the problems of the prior art, the present invention provides magneto-optical recording that is capable of high-speed, high-density recording and is compatible with the magnetic field modulation method, which can sufficiently cope with the above-mentioned speeding up of information processing and replacement of hard disks, etc. The purpose is to provide a medium.

[Means and effects for solving the problem] In order to achieve the above object, according to the present invention, a magneto-optical recording layer is provided on a substrate via a dielectric layer, and a heat insulating layer is further provided on the magneto-optical recording layer. In the magnetic recording medium, a heat absorption layer is provided on the heat insulation layer, and the heat conductivity at room temperature is in the order of the heat insulation layer, the dielectric layer, and the heat absorption layer, and the dielectric layer has a refractive index of 2. A magneto-optical recording medium characterized in that the number of magneto-optical recording media is one or more is provided.

When magneto-optical recording is performed on a magneto-optical recording medium using the magnetic field modulation method, the shape of the recording bit is as shown in FIG. 3 in the diagram
1 is a magneto-optical recording medium, 32 is a recording laser beam, 33 is a recording bit, 33' is a bit tail, 34 is a 100°C thermal isotherm, and 35 is a 70°C thermal isotherm. Now, the magneto-optical recording medium 31 moves to the right as indicated by the arrow P in the figure, and the recording laser beam 32 is continuously irradiated in the area C, and the magneto-optical recording medium 31
Suppose that the magnetic field moves from tl to t2 in the figure during the time from the on-time (t□) to the off-time (t2) of the magnetic field. Further, the recording start temperature of this magneto-optical recording medium 31 is set to 150°C. In this case, the thermal isotherms at 150° C., 100° C., and 70° C. are 33 and 34.35, respectively, and 33 is the recording bit. The area C' is not recorded because the medium temperature is high when the recording magnetic field is off, and is magnetized in the erasing direction. The thermal isotherm in the magneto-optical recording medium 31 is determined by its thermal conductivity, and the shape of the recording bit is influenced by the thermomagnetic characteristics of the magnetic film and the frequency characteristics (rise and fall of the magnetic field) of the magnetic head.

In order to perform high-density recording in magneto-optical recording using the magnetic field modulation method, the recording bit length must be 1/Ja1 or less.

In addition, the bit shape must be sharp and the length of the tail at the rear end of the bit (33' in FIG. 4) must be short. If the recording bit length is long, it becomes a hindrance to increasing the recording density, and if the trailing end of the recording bit is long and its shape is disordered, noise becomes large and the reproduction C/N deteriorates.

In view of the above, as a result of intensive research, the present inventor has developed a structure in which the layer structure of a magneto-optical recording medium is laminated in this order: a substrate, a dielectric layer, a magneto-optical recording layer, a heat insulating layer, and a heat absorption layer. By specifying the conductivity to increase in the order of heat insulating layer, dielectric layer, and heat absorption layer, and specifying the refractive index of dielectric constant to be 2.1 or more, it was found that the above target values and target characteristics could be achieved. Ta.

The present invention will be explained in more detail below with reference to the drawings.

FIG. 1 is a sectional view showing an example of the layer structure of a magneto-optical recording medium according to the present invention. In the figure, 1 indicates a substrate, on which a dielectric layer 2, a magneto-optical recording layer 3, a heat insulating layer (a protective layer) are provided. ) 4, the heat absorbing layer (heat sink layer) 5 is successively laminated, and an organic protective layer or bonding layer 6 is formed as required.

First, as the material of the substrate 1, plastics such as polycarbonate, methyl methacrylate, polyolefin, epoxy resin, or glass can be used. Guide tracks and preformats may be formed on the substrate 1 in advance. In addition, the laser beam incident surface of the substrate 1 is set to H,
In order to prevent the intrusion of O10□, it may be coated with a dielectric layer, a hydrophobic layer, a gas-resistant layer (for example, a fluororesin layer), or the like.

The dielectric layer 2 serves to prevent 820.02 from entering from outside the substrate and deteriorating the magnetic properties of the recording layer 3, and also to enhance the magneto-optic effect (Kerr rotation angle θk) through multiple reflections of light. Here, we will consider the characteristics of the dielectric layer 2 that are optimal for fulfilling this role. FIG. 5 is a graph showing the relationship between the dielectric layer thickness, absorption coefficient A, and reflectance R when the medium structure is as shown in FIG. 6. In Fig. 6, 61 is a glass substrate, 62 is 5iXN,
Dielectric layer (refractive index 2.3), 63 is TbDyFeCo magnetic layer, 64 is 5i
XN is a protective layer, and 65 is a laser beam. The thickness of the magnetic layer 63 is constant (700 layers). In FIG. 5, the absorption rate A becomes maximum when the thickness of the dielectric layer 62 is around 600 to 700, and it can be seen that the recording sensitivity can be improved if the thickness is around this range. Further, FIG. 7 is a graph showing the relationship between the dielectric layer thickness and the Kerr rotation angle 0. This figure shows that near the film thickness where the absorption rate A is maximum, the Kerr rotation angle θ also increases due to the multiple reflection (enhancement) effect. Further, FIG. 8 shows the relationship between the refractive index, absorption coefficient A, and reflectance R of the dielectric material used for the dielectric layer. From this figure, it can be seen that the absorption rate A is maximum when the refractive index n is 2.5 to 2.7. From the above, in the dielectric layer 2 of the magneto-optical recording medium of the present invention, a material having a refractive index n of 2.1 or more is used in a film thickness of 500 to 800 mm. In addition, from the viewpoint of heat loss due to thermal conduction, the thermal conductivity of the dielectric layer 2 is 0.
It is preferable that it is 1CaQ/Cm-8.degree. C. or less. Such a material is tt, specifically S l x N Y
, AflN, 5iO1AQON, 1QsiN, Zn
S, Aα5iNO, etc. are preferably used. As a film forming method, a sputtering method, a vapor deposition method, an ion blating method, etc. are used.

Next, to explain the recording layer 3, this recording layer 3 includes:
At least one rare earth metal (Tb, DytGd+
An amorphous magnetic alloy film is used, which is made of Ha, ttr, etc.) and at least one transition metal, and has an axis of easy magnetization in a direction perpendicular to the film surface. The magnetic alloy film has a composition in which the concentration of the rare earth metal is compensated (IM, , -MTM1=, where the magnetic moment of the rare earth metal in the magnetic alloy film at room temperature is 'RE, and the magnetic moment of the transition metal is 'TM).

Use a material that is close to the composition (composition) and rich in rare earth metals (predominant). For compensation composition, rare earth metal-rich magnetic alloy films generally have a larger coercive force Hc at room temperature, a larger slope of the temperature characteristic curve of the coercive force He, and a lower saturation magnetization Ms value than transition metal-rich ones. Shows a small tendency. Note that the concentration of rare earth metal z (aton+%) in the magnetic alloy film is the concentration in the compensation composition zo (
atom%), zo<z(z.

Preferably it is +4. If the value of 2 becomes too large, the coercive force Hc and the Kerr rotation angle θ at room temperature will rapidly decrease, making it unsuitable for the recording layer of a magneto-optical recording medium.

Here, as an example, FIGS. 9 and 10 respectively show rare earth metal-rich magnetic alloy films (Tb1□, 4Dy1□, 5F
eGG, 1lCoe, 3) and transition metal-rich magnetic alloy film CGdx□-1Tbxs, -7Feb□-5cOB
, 4) shows the temperature dependence of the coercive force He and the Kerr rotation angle O3. Rare earth metal rich T b, D y shown in FIG.
The Curie temperature Tc of the F e Co magnetic alloy film is 168°C.
The coercive force Hc is low near the Curie temperature Tc.
The temperature characteristic curve changes linearly with a large slope.

In such a magnetic alloy film, the difference in coercive force He between the recording bit and non-recording area is large and changes digitally, so the length of the recording pits 1~ formed by the magnetic field modulation method is short and the bit The tail is short and has a sharp shape. On the other hand, the transition metal-rich GdTbFe shown in FIG.
The Co magnetic alloy film has a high Curie temperature Tc of 236°C.
The temperature characteristic curve of the coercive force He has a small slope near the Curie temperature Tc, and has a long tail. In such a magnetic alloy film, the difference in coercive force He between the recorded bit and non-recorded area is small, the tail of the recorded bit is long, and the bit shape is
As shown in Figure 1, the image is not sharp and is distorted. Furthermore, the size of the recording bits becomes irregular, making it susceptible to small fluctuations in the composition of the magnetic alloy film, which is undesirable. As described above, the larger the gradient value of the coercive force He near the Curie temperature Tc is, the better, and it is preferable that it changes linearly without drawing a long tail. The quality of the temperature characteristics of the coercive force He is determined by the Curie temperature T.
When the coercive force at a temperature 50°C lower than c (Tc - 50°C) is He5o, this He. It can be evaluated using the slope value divided by 50°C + 1c, 150 (Os7°C). The gradient value He5o 15o of the magnetic alloy film of the present invention is preferably 20 or more. By the way, TbDyFeC in Figure 9
o For magnetic alloy films, ties o > 25000e,
The slope value Hcso150>50(Oe/'c),
In the GdTbFeCo magnetic alloy film shown in FIG. 10, Hc. 4
2000e, gradient value He,. 750 4 (Oe/℃).

Also, regarding saturation magnetization Ms, rare earth metal-rich magnetic alloy films exhibit better characteristics than transition metal-rich ones, as described below. Figure 12 is a graph showing the temperature dependence of the saturation magnetization of rare earth metal-rich and transition metal-rich magnetic alloy films, and Figure 13 is a graph showing the magnetization distribution around the recording bit and the stray magnetic field distribution inside the recording bit. be. FIG. 14 is a model diagram of bit formation during recording. In FIG. 14, 71 is a magneto-optical recording medium, 72 is a substrate, 73 is a magnetic alloy film, and 74 is a recording laser beam. As shown in Fig. 12, the saturation magnetization Ms of the transition metal-rich magnetic alloy film does not decrease much even if the temperature rises by 2'', and the Curie temperature Tc
It shows a tendency to rapidly decrease in the vicinity. On the other hand, the saturation magnetization Ms of the rare earth metal-rich magnetic alloy film shows a tendency to linearly decrease as the temperature increases. The above tendency in the transition metal-rich magnetic alloy film is due to the fact that the saturation magnetization Ms remains largely as a residual magnetizer around the recording bit, compared to the rare earth metal-rich magnetic alloy, as shown in FIG. It is. This has a negative effect on the recording and erasing processes. That is, in the recording process, as shown in FIG. 14, the demagnetizing field Hd due to residual magnetization acts on the laser beam irradiated recording section in the same direction as the external magnetic field Hex, expanding the recording bit, so that the recording of minute recording bits is becomes difficult. On the other hand, in the erasing process, the demagnetizing field 1 (d) acts in the opposite direction, so an external magnetic field that is 28 d larger than that during recording is required. The magnitude of the external magnetic field is changed at a frequency of 10 MHz between recording and erasing. Therefore, magnetic alloy films rich in transition metals are not particularly suitable for magnetic field modulation methods.Magnetic alloy films rich in rare earth metals do not have the above disadvantages and can easily record with minute recording bits. The saturation magnetization Ms of the magnetic alloy film of the present invention is as small as possible, and is also compatible with the magnetic field modulation method.
150 Gauss or less, more preferably ], 00 Gauss
It is desirable that it be below ss.

On the other hand, the thickness of the magnetic alloy film is largely related to recording sensitivity, that is, recording laser power. Figure 15 shows the film thickness t of the magnetic alloy film and the minimum recording start laser power Pm (bit length 1 μm,
The relationship with the second-order high-frequency minimum value is shown in a graph. Also,
Figure 16 shows the film thickness t, absorption rate A, and reflectance R of the magnetic alloy film.
A graph shows the relationship between As can be seen from Figure 15,
The minimum laser power Pm for starting recording becomes minimum when the film thickness is 300, and the power Pm remains the same even if the film thickness is thinner or thicker.
increases. This means that the power Pm is pmceΔT−x
A (1-R-T) (ΔT is the temperature difference between the Curie humidity Tc and room temperature, t is the film thickness, A is the absorption rate, R is the reflectance, T
This is because the absorption rate A changes according to the relational expression (transmittance), and as shown in FIG. 16, when the film thickness becomes smaller than 300, the absorption rate A decreases rapidly. From the above, it is preferable that the thickness of the recording layer 3 is 300 to 600.

In addition, the recording layer 3 includes AQ, Ti, etc. to improve corrosion resistance.
It may contain at least one or more of Cr, Zr, Ni, In, Su, Cu, etc., and may further contain Sm, Nd, Pr, Ce, Pt, etc. to improve magneto-optical properties.
Au%Nb, Eu, Y.

At least one kind of B1 etc. may be contained.

As an amorphous magnetic alloy film that can be applied to the recording layer 3 of the magneto-optical recording medium of the present invention, (Tbxao-XDyX)Z(Fe
lao-, Coy)ion-Z(0<X<IOo, 3<
y<20. Preferably 50 < x < 100, 3
<y<10, and 2 is zo<z<zo+4, where zo is the compensation composition. ], (GdlllO-
xDy) OzCFel n++-ycOy) too-z
(0 < x < ioo, O < y < 10, and Z is zo < z < zo + 4, where zo is the compensation composition)
etc., but the invention is not limited thereto, and any material that satisfies the above conditions can be applied.

The heat insulating layer 4 serves to collect the heat generated in the recording layer 3 by laser irradiation during recording into the recording layer 3 without diffusing it, and also prevents the recording layer 3 from being oxidized and corroded by water and oxygen in the atmosphere. perform the role of Therefore, it is desirable that the thermal conductivity of the heat insulating layer 4 is lower than that of the dielectric layer 2, and the thermal conductivity is 5X 1O-2cafl/cm-s・℃
The following dielectric materials are preferably used. And, such dielectric materials include Six Ny, Sj, Oz
, 5iO1Zr02.5iZrN, etc. are optimal.

Furthermore, Tj, Pt, Cr, Nd, Mn, etc. may be added. The heat insulating layer 4 is formed to a thickness of 400 to 1000 layers using the same film forming method as for forming the dielectric layer.

The heat absorbing layer 5 functions to prevent heat diffusion in the heat insulating layer 4. That is, the heat generated in the recording layer 3 by laser irradiation during recording is conducted to the heat insulating layer 4, which has a low thermal conductivity, and the heat in the heat insulating layer 4 is conducted to the heat absorption layer 5, so that the heat generated in the heat insulating layer 4 is transferred to the heat absorbing layer 5. Heat diffusion is prevented.

As a result, as shown in FIG. 17(a), the tail at the rear end of the recorded bit is short, and the bit shape is sharp and faithful to the laser spot diameter. On the other hand, when there is no heat absorption layer 5, heat diffusion occurs in the heat insulating layer 4, and as shown in FIG. 17(b), the tail at the trailing edge of the recording bit is long and its shape is narrower than the laser spot diameter. .

Due to the above action, the heat absorption layer 5 has a thermal conductivity of 0.2ca.
Materials with a good temperature of Q/cm-s・℃ are used. Examples of such materials are 11. Pt, Au, Rh, Cu,
Ag, Cr, etc. or alloys thereof are most suitable. As the film forming method, methods such as sputtering method and vapor deposition method are used.
It is formed to a thickness of 0.00 to 600 people. If the thickness of the heat absorbing layer 5 is greater than 600 mm, heat diffusion occurs in the lateral direction of the heat absorbing layer 5, which requires strong recording laser power, which is undesirable, and if it is thinner than 200 mm, the above effect will not occur. You won't get any more.

An organic protective layer or bonding layer 5 is provided on the heat absorbing layer 5 if necessary, and the organic protective layer protects the heat absorbing layer 5, and the bonding layer performs bonding in a double-sided recording type medium. These organic protective layers or bonding layers 5 are formed using ultraviolet curable resins (UV resins), thermoplastic resins, plasma polymerized resins, etc. to a film thickness of 1 μL 11 to 100 layers by spinner coating or other methods. Ru.

Further, when a double-sided recording type magneto-optical disk is prepared by bonding two disks together, it is preferable to join the ends of the disks with a dielectric material or plastic.

〔Example〕

Examples of the present invention are given below, but the present invention is not limited to these Examples.

Example 1 A glass plate with an outer diameter of 130 mm, an inner diameter of 15 mm, and a thickness of 1 to 2 mm was used as a substrate, and a SixNy film (refractive index n: 2.3, thermal conductivity 0) was formed as a dielectric layer on the substrate in an RF magnetron sputtering device. , 04caalCm-8・
℃) by sputtering at a deposition rate of 32 people/min.
Formed to the thickness of a human.

Next, in the same sputtering apparatus, Tbtz, 4Dyzz-sFeg6. A sco+z3 magnetic film was formed to a thickness of 400 layers by sputtering at a deposition rate of 40 layers/minute. The magnetic properties of this recording layer were as follows: Curie temperature Tc=168° C., coercive force Hc=3.7 kOe, and saturation magnetization Ms=108 Gauss. Then, on top of that,
Similarly, a SixNy film (thermal conductivity: 0.04 CaQ/Cm-8.degree. C.) was formed as a heat insulating layer by sputtering at a deposition rate of 40 persons/min. Finally, apply UV resin (UDAL-39 (manufactured by Dainichiseika Chemical Co., Ltd.) on the heat absorption layer using a spin cord.
) was deposited to a thickness of 307 ann, and then cured by ultraviolet irradiation to form an organic protective layer to obtain a magneto-optical recording medium.

Examples 2 to 6 Magneto-optical recording media were obtained in the same manner as in Example 1 using the materials shown in Tables 1 and 2 for each layer, each layer having the thickness shown in Table 3. The magnetic properties of the recording layer were as shown in Table 2, and the refractive indexes or thermal conductivities of the dielectric layer, heat insulating layer, and heat absorption layer were as shown in Table 3. Note that the epoxy resin was applied and formed using a heated roller.

Table-2 = 19- Comparative example Using polycarbonate as the substrate material, Table-3 was coated with the materials shown in Table-1 and Table-2 on the substrate in the same manner as above.
A dielectric layer, a recording layer, and a heat insulating layer were formed with the film thicknesses shown in Figure 3. A magneto-optical recording medium was obtained by forming an organic protective layer on the heat absorbing layer without providing a heat absorption layer.

The recording and reproducing characteristics of each of the magneto-optical recording media produced as described above were evaluated under the following conditions.

・Flying height 2 to 4 (μ+a) on the organic protective layer of the magnetic head
・Recording frequency 15 (MHz) ・Linear speed 22 (m/s) ・Medium rotation speed 3600 (rpm) ・Recording laser wavelength 780 (nm) ・Recording laser power (medium surface) 4 to 10 (mW) ・Laser spot Diameter approx. 1 (voice) ・Bias magnetic field ±200-300 (Os) ・Reproduction laser wavelength 780 (ru++) ・Reproduction laser power 2
(ms) When recording, the laser beam is set to a channel clock of 30MH.
Pulses are generated in synchronization with Z, and the magnetic head is 15MH
The information signal was modulated at a frequency of z. The above characteristic evaluation results are shown in Table-4.

Table 4 As shown in the table, the magneto-optical recording medium of this example has a recording laser power of 8 mW or less and a recording bit length of 0° 8 μm.
The recording bit shape was sharp and trailing was small, and the reproduction C/N was 50 dB or more, allowing high speed and high density, and was compatible with the magnetic field modulation method.

On the other hand, in the magneto-optical recording medium of the comparative example without a heat absorption layer, the recording laser power is 7 mV or less, but the recording bit length is 1.1 μm, the shape is irregular, there is a lot of tailing, and the reproduction C/ N was inferior at 40 dB.

〔Effect of the invention〕

As explained in detail above, according to the present invention, since the heat absorbing layer is provided on the heat insulating layer, heat diffusion in the heat insulating layer is prevented, the recording bit length is short, the bit shape is sharp, and there is no trailing. It is possible to provide a magneto-optical recording medium that is short, enables high-speed, high-density recording, and is compatible with the magnetic field modulation method.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the structure of the magneto-optical recording medium according to the present invention, Fig. 2 is an explanatory diagram showing the drawbacks of the optical modulation method, and Fig. 3 is a floating magnetic head and magneto-optical recording used in the magnetic field modulation method. A diagram showing the positional relationship with the medium, Figure 4 is an explanatory diagram of recording bits using the magnetic field modulation method, and Figure 5 is the film thickness and absorption rate A of the dielectric layer.
6 is a cross-sectional view showing the structure of the magneto-optical recording medium used to measure the data shown in FIG. 5, and FIG. 7 is a graph showing the relationship between dielectric layer thickness and Kerr rotation angle θ. FIG. 8 is a graph showing the relationship between the refractive index of the dielectric layer and the absorptivity A and reflectance R. FIG. 9 is a graph showing the relationship between the refractive index of the dielectric layer and the absorption rate A and reflectance R. Graph showing temperature dependence of Kerr rotation angle Ok and coercive force He, 1st
Figure 0 is a graph showing the temperature dependence of Kerr rotation angle θ and coercive force Hc in an example of a transition metal-rich magnetic alloy film.
Figure 11 is a diagram showing the recording bit shape of transition metal-rich magnetic alloy films, Figure 12 is a diagram showing the temperature dependence of saturation magnetization of rare earth metal-rich and transition metal-rich magnetic alloy films, and Figure 13 is a diagram showing the temperature dependence of saturation magnetization of rare earth metal-rich and transition metal-rich magnetic alloy films. A graph showing the magnetization distribution around the recording bit and the stray magnetic field distribution inside the bit in metal-rich and transition metal-rich magnetic alloy films. Figure 14 shows the model during recording. Figure 15 shows the film thickness of the magnetic alloy film. 16 is a graph showing the relationship between the recording start minimum laser power and the recording start minimum laser power; FIG. 16 is a graph showing the relationship between the thickness of the magnetic alloy film and the absorption rate A and the reflectance R
FIG. 17 is a diagram showing a comparison of recording bit shapes of a magneto-optical recording medium provided with a heat absorption layer and a magneto-optical recording medium without a heat absorption layer. 1... Substrate 2... Dielectric layer 3... Magneto-optical recording layer 4... Heat insulating layer 5... Heat absorption layer 6... Organic protective layer or bonding layer Patent applicant Rico Co., Ltd.

Claims (1)

[Claims] (1) In a magneto-optical recording medium in which a magneto-optical recording layer is provided on a substrate via a dielectric layer, and a heat insulating layer is further provided on top of the magneto-optical recording layer, a heat absorption layer is provided on the heat insulating layer to improve heat conduction at room temperature. 1. A magneto-optical recording medium, wherein the refractive index of the heat insulating layer, the dielectric layer, and the heat absorption layer are increased in this order, and further, the dielectric layer has a refractive index of 2.1 or more.