JPH11203739A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which allows the stable writing of recording marks sufficiently smaller than a beam spot without the execution of strict control of a recording power and allows the reproduction of the written small recording marks while stably holding the marks. SOLUTION: The optical recording medium formed with >=1 functional films 13 contributing to the recording and reproducing of information on a substrate is composed of the functional films of a layer structure contiguously laminated with the first layer 13-1 consisting of an alloy of a prescribed compsn. and the second layer 13-2 consisting of an alloy of the compsn. different from the compsn. of the first layer 13-1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium on which information can be rewritten.

[0002]

2. Description of the Related Art An optical disk (optical recording medium) is attracting attention mainly as a recording medium for audio and computers since information can be rewritten, and its large capacity is desired. In order to meet this demand for higher capacity, it is necessary to have both a technology for recording information at high density and a technology for accurately reproducing information recorded at high density.
In recent years, its development has been promoted.

Here, such rewritable optical disks are roughly classified into a magneto-optical disk and a phase-change disk depending on the material of a functional film (such as a memory film) contributing to recording and reproducing of information and the recording / reproducing method. Is done. Hereinafter, the recording and reproduction of information will be described using a magneto-optical disk as an example.
When recording information on a magneto-optical disk, a recording beam is irradiated while intermittent power according to the information,
In addition, an external magnetic field in a fixed direction is applied (light modulation recording method).

[0004] In a region heated by the irradiation of the recording beam and heated to a temperature near the Curie temperature Tcm of the memory film (hereinafter referred to as a "heated region"), the coercive force of the memory film is reduced, and the magnetization direction is changed to the outside. It can be reversed according to the direction of the magnetic field. The magnetic domain having the magnetization direction opposite to that of the surroundings becomes stable when the coercive force of the memory film increases as the temperature decreases, and becomes a recording mark.

Therefore, by irradiating the recording beam intermittently according to the information, the above-described recording marks can be successively formed on the memory film of the magneto-optical disk, and the information can be recorded. Here, in order to record information at high density, it is necessary not only to reduce the distance between adjacent recording marks, but also to reduce the size of the recording marks themselves.

When a small recording mark is formed by using the above-described light modulation recording method, a temperature distribution generated in a beam spot by irradiation of a recording beam is used, and the above-described heating area (temperature) is applied only to a small area in the beam spot. Is Tc
m). The method of forming a small recording mark by making the heating area smaller than the beam spot in this way is called a pen tip recording method.

Therefore, if this pen tip recording method is used,
Recording marks smaller than the beam spot can be successively formed on the magneto-optical disk, and information can be recorded at a high density. On the other hand, information recorded at high density using the pen tip recording method is based on magnetic super-resolution (Magnet
It can be accurately reproduced using the ically induced Super Resolution technology.

In recent years, various types of magnetic super-resolution techniques have been proposed. For example, CAD which performs reproduction in a region in a beam spot where the temperature is higher than a predetermined temperature is proposed.
(Center Aperture Detection) method, magnetostatic coupling method, and FAD (Fro
nt Aperture Detection) and D-RAD (Doublemasked Rear Apert
ure Detection) method (for example, JP-A-4-255946)
There is.

In any of these methods, recording marks smaller than a beam spot formed by using the pen tip recording method can be accurately reproduced one by one only in an area smaller than the beam spot. As described above, in a magneto-optical disk, information can be written at a high density by using a pen tip recording method, and the information written at a high density can be accurately reproduced by using a magnetic super-resolution technique, thereby increasing the capacity. Attempts have been made.

[0010]

In writing one recording mark smaller than the beam spot by the above-described pen tip recording method, usually, the smaller the size of the recording mark, the longer the irradiation time of the recording beam. Must be shorter. This is because the shorter the recording beam irradiation time, the smaller the above-mentioned heating area (the area where the temperature has increased to near Tcm).

However, on the other hand, when the irradiation time of the recording beam is shortened, the temporal fluctuation (noise) of the power of the recording beam greatly influences, and the size of the small heating region varies. Become. As is well known, a memory film of a magneto-optical disk on which a recording mark is written is an alloy film of one composition (for example, a uniform alloy film of a rare earth metal and a transition metal, or a rare earth metal layer and a transition metal layer). (An alloy film obtained by laminating at a constant cycle).

Therefore, the recording power margin when writing a recording mark smaller than the beam spot on the memory film using the pen tip recording method becomes narrower as the irradiation time of the recording beam is shorter (the smaller the recording mark is).
For this reason, the variation in the size of the heating area is directly reflected as the variation in the size of the recording marks, and the size of the small recording marks formed one after another on the magneto-optical disk tends to be non-uniform.

Here, in order to form only small recording marks of a desired size one after another stably on the magneto-optical disk, it is necessary to control recording power extremely strictly. In this case, the control circuit of the power of the recording beam becomes very complicated.

Further, the small recording mark formed by the above-mentioned pen tip recording method is reduced not only in the direction along the track but also in the track width direction, and has a very small area. Therefore, even if a small recording mark can be formed in the memory film by the pen tip recording method, the coercive force is low in the memory film composed of the alloy film of one composition, and the magnetization direction of the recording mark is opposite to the magnetization direction. It may disappear due to the influence of a certain surrounding, or may be in an unstable state where it cannot be reliably reproduced even if it does not disappear.

An object of the present invention is to stably write even a recording mark sufficiently smaller than the beam spot without strictly controlling the recording power, and to stably hold the written small recording mark. An object of the present invention is to provide an optical recording medium that can reproduce information while reproducing.

[0016]

According to a first aspect of the present invention, there is provided an optical recording medium in which one or more functional films contributing to recording and reproduction of information are formed on a substrate. At least one of the films is formed of a functional film having a layer structure in which a first layer made of an alloy having a predetermined composition and a second layer made of an alloy having a different composition from the first layer are stacked adjacent to each other. It was done.

Therefore, according to the first aspect of the present invention, the recording power margin is increased as compared with the case where all of the one or more functional films are formed of an alloy film having one composition. Even a recording mark sufficiently smaller than the beam spot can be stably written. Further, as compared with the case where all of the one or more functional films are formed of an alloy film of one composition, information can be stably held over a wide temperature range, so that a small recorded mark written can be obtained. Can be reproduced while maintaining the stability.

The invention described in claim 2 is the same as the invention described in claim 1.
3. The optical recording medium according to item 1, wherein the functional film having a layered structure is
In this configuration, a basic layer including a layer and a second layer is repeatedly laminated. Therefore, according to the second aspect of the present invention, the recording power margin is reliably expanded, and it is possible to stably write even a recording mark sufficiently smaller than the beam spot. Further, since information can be stably held over a wider temperature range, a small recorded mark can be reproduced while being stably held.

Further, the invention described in claim 3 is the first invention.
Alternatively, in the optical recording medium according to claim 2, both the first layer and the second layer are magnetic layers containing an alloy composed of a rare earth metal and a transition metal. Therefore, according to the third aspect of the present invention, it is possible to stably write even a recording mark sufficiently smaller than the beam spot by expanding the recording power margin, and to have a sufficient coercive force to hold information over a wide temperature range. As a result, a magneto-optical recording medium capable of reproducing even small recording marks stably can be obtained.

The invention described in claim 4 is the third invention.
Wherein the rare-earth metal forming the first layer and the rare-earth metal forming the second layer are the same element, and the transition metal forming the first layer and the transition metal forming the second layer are the same. These are composed of the same element. Therefore, according to the fourth aspect of the present invention, it is possible to stably write even a recording mark sufficiently smaller than the beam spot by enlarging the recording power margin, and to have a sufficient coercive force to hold information over a wide temperature range. Therefore, a magneto-optical recording medium having a simple configuration capable of stably holding and reproducing even small recording marks can be obtained.

The invention described in claim 5 is the same as the invention in claim 4.
Wherein the first layer is composed of a magnetic layer in which sub-lattice magnetization of rare earth metal is predominant, and the second layer is a magnetic layer in which sub-lattice magnetization of transition metal is predominant.

Therefore, according to the fifth aspect of the present invention, it is possible to stably write even a recording mark sufficiently smaller than the beam spot by reliably expanding the recording power margin, and to retain information over a wide temperature range. Therefore, a magneto-optical recording medium having a simple configuration capable of stably holding and reproducing even small recording marks can be obtained.

[0023] The invention described in claim 6 is the first invention.
6. The optical recording medium according to claim 1, wherein at least a first functional film for holding recorded information is formed on a substrate. In this case, this first
Is composed of a functional film having a layered structure in which a first layer and a second layer are stacked adjacent to each other. Therefore, according to the sixth aspect of the present invention, the recording power margin is enlarged as compared with the case where the first functional film is formed of an alloy film having one composition, and therefore, is sufficiently smaller than the beam spot. Even a recording mark can be stably written. Further, compared to the case where the first functional film is formed of an alloy film having one composition, information can be stably held over a wide temperature range, so that small written recording marks can be stably written. You can also play while holding.

[0024] Further, the invention described in claim 7 is based on claim 1.
6. The optical recording medium according to claim 1, wherein at least a first functional film holding recorded information on the substrate and a part of the first functional film corresponding to a temperature distribution in a reproduction beam irradiation area. A second functional film in which a perpendicular magnetization region corresponding to the magnetization direction of the first functional film is formed in the region. In this case, at least the first functional film is formed of a functional film having a layer structure in which the first layer and the second layer are stacked adjacent to each other.

Therefore, according to the invention of claim 7, since the recording power margin is expanded, even a recording mark sufficiently smaller than the beam spot can be stably written on the first functional film. Further, since the information can be stably held over a wide temperature range, the magnetic super-resolution by the function of the second functional film can be stably held while the small recording mark written on the first functional film is stably retained. It can also be accurately reproduced by technology.

The invention described in claim 8 is the same as that in claim 7.
In the optical recording medium described in the above, the third function of transferring the magnetization direction of the first functional film to the second functional film in a partial region between the first functional film and the second functional film It is a film formed. In this case, the third functional film is an in-plane magnetization film, and has a higher Curie temperature than a temperature at which the in-plane magnetization state changes to a perpendicular magnetization state. And
In the reproduction beam irradiation region, a partial region is set in a region where the temperature is higher than the temperature at which the in-plane magnetization state of the third functional film changes to the perpendicular magnetization state and lower than the Curie temperature of the third functional film. Is formed.

Therefore, according to the present invention, even a recording mark sufficiently smaller than the beam spot can be stably written on the first functional film by expanding the recording power margin. Further, since the information can be stably held over a wide temperature range, the small recording mark written on the first function film can be stably held while the second function film and the third function film are kept. Accurate reproduction can also be performed by the D-RAD method by function.

Further, the invention according to claim 9 is the same as the invention according to claim 7.
In the optical recording medium described in the above, the third function of transferring the magnetization direction of the first functional film to the second functional film in a partial region between the first functional film and the second functional film It is a film formed. In this case, the third functional film is a perpendicular magnetization film. Then, a part of the reproduction beam irradiation region is formed in a region lower than the Curie temperature of the third functional film.

Therefore, according to the ninth aspect of the present invention, even if the recording mark is sufficiently smaller than the beam spot, the first functional film can be stably written by expanding the recording power margin. Further, since the information can be stably held over a wide temperature range, the small recording mark written on the first function film can be stably held while the second function film and the third function film are kept. Accurate reproduction can also be performed by the FAD method based on the function.

According to a tenth aspect of the present invention, in the optical recording medium according to the seventh aspect, a nonmagnetic film or a paramagnetic film is formed between the first functional film and the second functional film. It was done. Therefore, according to the tenth aspect, even if the recording mark is sufficiently smaller than the beam spot, it is possible to stably write to the first functional film by expanding the recording power margin. Further, since the information can be stably held over a wide temperature range, the small recording mark written on the first function film can be stably held while the second function film and the non-magnetic film or the normal Accurate reproduction can also be performed by the magnetostatic coupling system by the action of the magnetic film.

According to an eleventh aspect of the present invention, in the optical recording medium according to any one of the sixth to tenth aspects, information is temporarily stored on an opposite side of the first functional film from the substrate. A fourth functional film for transferring the recorded magnetization direction representing the information to the first functional film; and a fourth functional film for transferring the magnetization direction of the fourth functional film to the first functional film. And a fifth functional film for forcibly aligning the magnetization direction in one direction. In this case, both the fourth functional film and the fifth functional film are perpendicular magnetization films.

Therefore, according to the eleventh aspect of the present invention, a recording mark sufficiently smaller than the beam spot is formed by using the overwrite recording system by the function of the fourth functional film and the fifth functional film. Can be stably written to the first functional film. Further, since information can be stably held over a wide temperature range, small recording marks written on the first functional film can be stably held and accurately reproduced by the magnetic super-resolution technique. .

According to a twelfth aspect of the present invention, in the optical recording medium of the eleventh aspect, the first functional film and the fourth
When the magnetization direction of the fourth functional film is forcibly aligned in one direction between the fourth functional film and the fourth functional film,
A sixth functional film for weakening a magnetic coupling force from the magnetic film to the first magnetic film is formed. Therefore, claim 12
According to the invention described in (1), a recording mark sufficiently smaller than a beam spot is formed by using an overwrite recording method by the function of the fourth functional film, the fifth functional film, and the sixth functional film, thereby increasing the recording power margin. Accordingly, writing can be stably performed on the first functional film. Furthermore, since information can be stably held over a wide temperature range,
The small recording mark written on the first functional film can be accurately reproduced by the magnetic super-resolution technique while being stably held.

According to a thirteenth aspect of the present invention, in the optical recording medium according to the eleventh or twelfth aspect, a perpendicular magnetization film is provided between the fourth functional film and the fifth functional film. Thus, when information is temporarily recorded on the fourth functional film,
A seventh functional film for weakening the magnetic coupling force from the fifth functional film to the fourth functional film is formed. Therefore, according to the thirteenth aspect of the present invention, at least the fourth functional film, the fifth functional film, and the seventh functional film use an overwrite recording method, and a recording mark sufficiently smaller than the beam spot is formed. In addition, it is possible to stably write on the first functional film by increasing the recording power margin. Further, since information can be stably held over a wide temperature range, small recording marks written on the first functional film can be stably held and accurately reproduced by the magnetic super-resolution technique. .

According to a fourteenth aspect of the present invention, there is provided the optical recording medium according to any one of the eleventh to thirteenth aspects, wherein the first functional film and the third functional film are disposed between the first functional film and the third functional film. An eighth functional film, which is a perpendicular magnetization film and whose Curie temperature is lower than the Curie temperature of the first functional film, is formed. Therefore, according to the fourteenth aspect of the present invention, the recording mark sufficiently smaller than the beam spot is formed by using the overwrite recording method by the operation of at least the fourth functional film and the fifth functional film, thereby increasing the recording power margin. Accordingly, writing can be stably performed on the first functional film.
Further, since information can be stably held over a wide temperature range, the second function film, the third function film, and the like can be stably held while the small recording mark written on the first function film is stably held. Accurate reproduction can also be performed by the magnetic super-resolution technique by the function of the eighth functional film.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. Note that the first embodiment corresponds to claims 1 to 8. The magneto-optical disk 10 according to the first embodiment is a rewritable disk, and a protective film 22, a reproducing film 11, a reproducing intermediate film 12, a memory film 13, and a protective film are formed on a substrate 21 from above to below in FIG. 23 are sequentially formed.

The memory film 13 (corresponding to the first functional film of claims 6 to 8) is a film for retaining recorded information. The reproducing film 11 (corresponding to the second functional film of claims 7 and 8) and the reproducing intermediate film 12 (third of claim 8)
Is a film that performs an operation of reproducing information recorded in the memory film 13. The protective films 22 and 2
Reference numeral 3 denotes a film that protects each of the films 11 to 13 described above.

Here, the composition, film thickness, film forming method and function of each of the films 11 to 13, 22, and 23 constituting the magneto-optical disk 10 will be individually described. The memory film 13 is made of terbium (Tb) which is a rare earth metal and iron which is a transition metal.
A magnetic film composed of (Fe) and cobalt (Co),
As shown in FIG. 2, two adjacent layers 13-1 and 1
The basic layer 13a composed of 3-2 has a layered structure (multilayer) repeatedly laminated.

One of the layers 13-1 of the basic layer 13a constituting the memory film 13 having such a layer structure is an alloy layer in which the sub-lattice magnetization of the rare earth metal is dominant (corresponding to the first layer of claims 1 to 7). In the following, the specific composition is represented by atomic percentage, Tb is 21 atomic%, Fe is 63.2 atomic%, and Co is 15.8 atomic%. (Hereinafter, the atomic percentage of the composition is expressed as Tb21Fe63.2Co1
5.8). This RE-rich alloy layer 13-
The thickness D1 of 1 is 2 nm.

The other layer 13-2 of the basic layer 13a constituting the memory film 13 having a layered structure has a different composition from the above-mentioned RE-rich alloy layer 13-1, and the sub-lattice magnetization of the transition metal is dominant. An alloy layer (corresponding to the second layer in claims 1 to 7; hereinafter, referred to as a “TM-rich alloy layer”). The specific composition of the TM-rich alloy layer 13-2 is Tb19Fe64.8Co
16.2 The thickness D2 of the TM rich alloy layer 13-2
Is 2 nm.

The memory film 13 having a layer structure in which the RE-rich alloy layer 13-1 and the TM-rich alloy layer 13-2 having such compositions and film thicknesses are stacked has magnetization perpendicular to the film surface ( This is a perpendicular magnetization film oriented in the vertical direction in FIG. The memory film 13 has a thickness D13 of 50 nm and a Curie temperature Tc13 of about 260 ° C. In this connection, as shown in FIG. 3, the formation of the memory layer 13 having such a layer structure is performed by mixing Tb, Fe, and Co according to the composition (Tb21Fe63.2Co15.8) of the RE-rich alloy layer 13-1. Alloy target 51 and TM rich alloy layer 1
According to the composition of 3-2 (Tb19Fe64.8Co16.2), Tb,
In a known co-sputtering apparatus 50 in which an alloy target 52 in which Fe and Co are mixed is separately arranged (argon gas is introduced, and gas pressure is 5 × 10 ⁻³ Torr).
, The substrate 21 attached to the pallet 54 is
It is performed while revolving around 4 (for example, 90 rpm). The thickness D1, TM of the RE-rich alloy layer 13-1
The thickness D2 of the rich alloy layer 13-2 depends on the rotation speed of the substrate 21,
The thickness D13 of the entire memory layer 13 is adjusted by the sputtering time, which is adjusted by the gas pressure and the power applied to each of the alloy targets 51 and 52.

The reproducing intermediate film 12 (FIG. 1) formed adjacent to the memory film 13 having the above-mentioned layer structure on the substrate 21 side is composed of gadolinium (Gd) which is a rare earth metal and Fe which is a transition metal. It is a magnetic film of one composition composed of a uniform alloy. The specific composition of the reproducing intermediate film 12 is as follows:
Gd29Fe71. The thickness D12 of the reproducing intermediate film 12
Is 50 nm.

The recycled intermediate film 1 having such a composition and thickness is as follows.
Reference numeral 2 denotes room temperature Tr (corresponding to the temperature of the magneto-optical disk 10 when no recording beam or reproduction beam is irradiated. For example, 20 ° C. to 30 ° C.), the magnetization is oriented in-plane (in the horizontal direction in FIG. 1). In-plane magnetization film. At a predetermined temperature Tx higher than the room temperature Tr, the reproduction intermediate film 12 changes its magnetization from the in-plane magnetization state to the perpendicular magnetization state (vertical direction in FIG. 1).
Changes to The predetermined temperature Tx is around 110 ° C.

Further, the Curie temperature Tc12 of the reproduced intermediate film 12 is higher than the above-mentioned predetermined temperature Tx (110 ° C.) and is about 220 ° C. The Curie temperature T
c12 (220 ° C.) is lower than either the Curie temperature Tc13 (260 ° C.) of the memory film 13 described above or the Curie temperature Tc11 of the reproduced film 11 described later. By the way, in the formation of the reproduction intermediate film 12 made of such a uniform alloy having one composition, the composition of the reproduction intermediate film 12 (Gd29Fe7
Using an alloy target mixed according to 1), the sputtering is performed in a known single-wafer sputtering apparatus (argon gas is introduced, and gas pressure is 5 × 10 ⁻³ Torr).

The reproducing film 11 is made of G which is a rare earth metal.
This is a magnetic film of one composition composed of a uniform alloy of d and transition metals Fe and Co. The specific composition of the reproducing film 11 is Gd25Fe60Co15. The thickness D11 of the reproducing film 11 is 30 nm. The reproduction film 11 having such a composition and thickness is a perpendicular magnetization film in which the magnetization is vertically oriented, like the memory film 13 described above. The Curie temperature Tc11 of the reproduced film 11 is at least the Curie temperature Tc12 of the reproduced intermediate film 12 (220 ° C.).
Higher than.

Incidentally, the formation of the reproduction film 11 made of a uniform alloy having one composition as described above is performed by the above-described reproduction intermediate film 1.
2, the composition of the reproducing film 11 (Gd25Fe60Co
Using an alloy target in which Gd, Fe, and Fe are mixed according to (15), the sputtering is performed in a known single-wafer sputtering apparatus (introducing an argon gas and at a gas pressure of 5 × 10 ⁻³ Torr).

The protective films 22 and 23 are made of silicon nitride, and each of the film thicknesses D22 and D23 is 70 nm.
Such protective layers 22 and 23 are formed in a sputtering apparatus in which a silicon target is arranged (gas pressure is set to 1 × 10
After reducing the pressure to ^-6 Torr or less, a mixed gas of argon and nitrogen was introduced to make the pressure 5 × 10 ^-3 Torr.)
The film is formed by well-known RF magnetron sputtering.

The substrate 21 is a transparent polycarbonate substrate (86 mm in diameter), and a guide groove is spirally formed on one surface thereof. Next, an operation of recording information on the memory film 13 having a layer structure in the rewritable magneto-optical disk 10 configured as described above by using the pen tip recording method will be described. In FIG. 4 illustrating the recording operation, the directions of magnetization of the films 11 to 13 are indicated by arrows.

The operation of recording information on the rewritable magneto-optical disk 10 is performed after the information already written on the memory film 13 is once erased (initialization of the magneto-optical disk 10). Here, the magneto-optical disk 10
The description of the initialization operation is omitted. When the initialization of the magneto-optical disk 10 is completed, the magnetization direction of the memory film 13 is uniformly aligned in the erasing direction (downward in FIG. 4) (hereinafter, referred to as “initial state”).

In recording information, the initialized magneto-optical disk 10 is rotated at a constant linear velocity (for example, 9 m / sec) by a motor of a recording / reproducing apparatus (not shown) (the direction is shown in FIGS. 4 and 5). 5 as indicated by arrow 10A). In recording information, the magneto-optical disk 10 is irradiated with a recording beam 31 (power is, for example, 8 mW) from a semiconductor laser (wavelength: 680 nm) of a recording / reproducing device (not shown) (FIG. 4).

At this time, the recording beam 31 is condensed to the diffraction limit by an objective lens (numerical aperture 0.55) of a recording / reproducing apparatus (not shown), and the diameter of the beam spot 31A on the magneto-optical disk 10 is approximately 1.1 μm. The irradiation of the recording beam 31 is as follows.
The operation is interrupted by turning on / off the semiconductor laser according to the information to be recorded. For example, when a recording mark having a mark length of 0.3 μm is recorded at a mark-to-mark distance of 0.3 μm, the recording beam 31 is given a duty ratio in consideration of the linear velocity of the magneto-optical disk 10 and the lighting / non-lighting cycle of the semiconductor laser. 3
Intermittent at 0%.

In recording information, a recording magnetic field Hw (for example, 300 (Oe)) having a constant magnitude generated from a magnetic coil of a recording / reproducing apparatus (not shown) is continuously applied to the beam spot 31A. (FIG. 4). The direction of the recording magnetic field Hw is opposite to the direction of magnetization (erasing direction) of the memory film 13 in the initial state (recording direction, upward in FIG. 4).

When the recording beam 31 (8 mW) is actually irradiated, a temperature distribution is generated in the magneto-optical disk 10, and one recording mark (1 μm) smaller than the beam spot 31A (1.1 μm) is obtained as follows. 0.3 μm) is written in the memory film 13. The magneto-optical disk 10 irradiated with the recording beam 31 has a temperature T1 (hereinafter, “recording temperature”) near the Curie temperature Tc13 (260 ° C.) of the memory film 13 only in a small area 31B located near the center of the beam spot 31A. ). Then, in a region 13B of the memory film 13 heated to the recording temperature T1 (hereinafter, referred to as a "heating region"), the coercive force is reduced or the magnetization is lost.

Thereafter, when the heating area 13B comes off the beam spot 31A with the rotation of the magneto-optical disk 10, and the temperature starts to decrease from the recording temperature T1, the heating area 13B
Magnetization starts to recover. At this time, the magnetization of the heating region 13B is affected by the continuously applied recording magnetic field Hw, and the recording state is reversed from the above initial state (the magnetization is in the recording direction (upward in FIG. 4)). Becomes

When the temperature of the heating area 13B further decreases and reaches near the room temperature Tr, the coercive force of the heating area 13B increases, and the magnetization of the heating area 13B in the recording state due to the effect of the recording magnetic field Hw becomes itself. The recording state (the magnetization is in the recording direction) is maintained by the coercive force of. In this way, one recording mark 13A (magnetic domain in the recording direction, mark length 0.3 μm) is written in the heating area 13B smaller than the beam spot 31A (1.1 μm).

Here, the small recording mark 1 as described above
In writing one 3A, the on / off cycle of the semiconductor laser is accelerated and the duty ratio is reduced, so that the irradiation time for one recording beam 31 is shortened and the heating area 13B is reduced. . As described above, when the irradiation time of the recording beam 31 is shortened, the size of the heating region 13B tends to vary due to a temporal variation (noise) of the power (8 mW) of the recording beam 31.

However, in the magneto-optical disk 10 of the first embodiment, as described above, the memory film 13 is not an alloy film of one composition, but a RE-rich alloy layer 13-1 and a TM-rich alloy layer having different compositions. This is a film having a layer structure in which the layer 13-2 and the layer 13-2 are stacked (FIG. 2). Thus, the structure of the memory film 13 is changed to the two alloy layers 13-1 and 13-1 having different compositions.
-2 is a layer structure in which the memory film 1
The recording power margin ΔP of No. 3 is larger than that of the memory film composed of an alloy film having one composition.

As shown in FIG. 6 (a diagram showing the relationship between the recording power and the CN ratio), the reason for the expansion of the recording power margin is that the original recording power margin Δp1 of one of the alloy layers 13-1 and the other, The recording power margin ΔP is slightly different from the original recording power margin Δp2 of the alloy layer 13-2 due to the difference in the composition. Therefore, the recording power margin ΔP can be reduced by forming these two alloy layers 13-1 and 13-2 into a layered structure. It is thought to expand.

As described above, in the memory film 13 having a layer structure in which the recording power margin ΔP is enlarged, the recording beam 31
Of the heating area 13B smaller than the beam spot 31A (1.1 μm) due to the time variation (noise) of the power, the fixed size (0.3 μm).
The recording mark 13A (the magnetization is in the recording direction) of m) can be stably written.

Note that the irradiation of the recording beam 31 is intermittent, and in a portion where the recording beam 31 is not irradiated, the magnetization of the memory film 13 is maintained in the above initial state (the magnetization is in the erasing direction). Therefore, the magneto-optical disk 10
By irradiating the recording beam 31 with intermittent power according to the information to be recorded, the recording mark 13 smaller than the beam spot 31A (1.1 μm) is formed.
A, 13A,... (Each mark length 0.3 μm) can be stably written to the memory film 13 having a layer structure one after another (distance between each mark 0.3 μm), and high-density information can be reliably recorded. .

At the time of recording the above information, the magnetization of the films 11 and 12 other than the memory film 13 disappears once in the small area 31B in the beam spot 31A similarly to the memory film 13, but thereafter the temperature decreases. When the temperature reaches around the room temperature Tr, the magnetization of the reproduction intermediate film 12 returns to the in-plane magnetization state, and the magnetization of the reproduction film 11 returns to the perpendicular magnetization state, and is stabilized (FIG. 4).
Next, an operation of reproducing the information using the D-RAD method in the rewritable magneto-optical disk 10 in which high-density information is recorded in the memory film 13 having a layer structure as described above will be described. In FIG. 7 illustrating the reproducing operation,
The direction of magnetization of each of the films 11 to 13 is indicated by an arrow.

When reproducing information, the magneto-optical disk 1
0 is irradiated with a reproduction beam 41 having a constant power (for example, 3.5 mW) from a semiconductor laser of a recording / reproducing apparatus (not shown) (FIG. 7). After passing through the polarizing filter, the reproducing beam 41 is applied to the magneto-optical disk 10 in a state of linearly polarized light. In reproducing the information, the reproducing magnetic field Hr (for example, 100 μm) having a constant magnitude is applied to the beam spot 41A of the reproducing beam 41 as in the above-described recording.
(Oe)) is applied (FIG. 7). The direction of the reproducing magnetic field Hr is opposite to the direction of the recording magnetic field Hw (recording direction) (erasing direction).

Further, in reproducing the information, the magneto-optical disk 10 is rotated at the same linear velocity (for example, 9 m / sec) as in the above-described recording, and is moved in the disk moving direction 10.
A (to the left as indicated by the arrows in FIGS. 7 and 8) moves across the beam spot 41A. When the reproducing beam 41 is actually irradiated, heat is accumulated in the magneto-optical disk 10 and a temperature distribution occurs. At this time, in the beam spot 41A of the magneto-optical disk 10, a temperature distribution is generated in which the temperature gradually decreases from the front to the rear (from left to right in FIGS. 7 and 8) in the disk moving direction 10A. ing. This is because, in the beam spot 41A, the reproduction beam 41 is irradiated for a longer time, and more heat is accumulated in the forward direction of the disk moving direction 10A.

Here, it is assumed that the inside of the beam spot 41A is divided into three regions having different temperatures. Part 3
The two areas are arranged in order from the front in the disk moving direction 10A.
They are a high temperature area 41F, a medium temperature area 41E, and a low temperature area 41D. In the first embodiment, the reproduction beam 41
By the irradiation of (3.5 mW), in the high temperature region 41F,
The temperature is lower than the Curie temperature Tc13 of the memory film 13 (260 ° C.) or the Curie temperature Tc11 of the reproducing film 11 and higher than the Curie temperature Tc12 of the reproducing intermediate film 12 (220 ° C.). In the middle temperature region 41E, the temperature is lower than the Curie temperature Tc12 (220 ° C.) of the reproduction intermediate film 12 and higher than the predetermined temperature Tx (110 ° C.) of the reproduction intermediate film 12. Further, in the low temperature region 41D, the reproduced intermediate film 1
2 is lower than the predetermined temperature Tx (110 ° C.) and higher than the room temperature Tr.

As described above, three regions 41 having different temperatures are used.
Beam spot 41A divided into D, 41E and 41F
Within each of the films 11 to 11 constituting the magneto-optical disk 10
Each of the 13 magnetizations is in a state as described below.
First, the magnetization of the memory film 13 will be described. The temperature in the beam spot 41A is in any of the areas 41D to 41F.
Also, the Curie temperature Tc13 of the memory film 13 (26
0 ° C.), which is a temperature at which the magnetization of the memory film 13 is maintained in the perpendicular magnetization state.

Further, the memory film 13 of the first embodiment
Is not an alloy film having a single composition as described above, but a film having a layered structure in which an RE-rich alloy layer 13-1 and a TM-rich alloy layer 13-2 having different compositions are laminated (FIG. 2). )
Therefore, the coercive force is sufficiently increased to retain information over a wider temperature range (the entire temperature range within the beam spot 41A) than the memory film formed of the alloy film of one composition. I have.

Accordingly, the recording mark 13A (the magnetic domain whose magnetization is in the recording direction) written in the memory film 13 having the layer structure.
Means that the size (0.3 μm) of the beam spot 41A
(1.1 μm), even if the area is very small, all the regions 41D to 41F in the beam spot 41A are not affected by the surroundings in the opposite magnetization direction (erasing direction). Is stably maintained in the state as recorded in.

On the other hand, the magnetization of the reproducing film 11 related to the operation of reproducing the information held in the memory film 13 is maintained in the perpendicular magnetization state in any of the regions 41D to 41F in the beam spot 41A. This is beam spot 4
This is because the highest temperature in 1A (the temperature of the high-temperature region 41F) is lower than the Curie temperature Tc11 of the reproduction film 11.
Similarly to the reproduction film 11, the magnetization of the reproduction intermediate film 12 related to the operation of reproducing the information held in the memory film 13 is controlled by the low-temperature region 41D and the medium-temperature region 41 in the beam spot 41A.
E, each of the high temperature regions 41F is in a different state according to the temperature. In the low-temperature region 41D, the temperature is lower than the predetermined temperature Tx (110 ° C.) of the reproduction intermediate film 12, so that the magnetization of the reproduction intermediate film 12 has an in-plane magnetization state (FIG. 7).
(Middle, horizontal direction) (FIG. 7). In the middle temperature region 41E, the temperature is lower than the Curie temperature Tc12 (220 ° C.) of the reproduction intermediate film 12 and higher than the predetermined temperature Tx (110 ° C.) of the reproduction intermediate film 12;
Has changed from the in-plane magnetization state to a perpendicular magnetization state (vertical direction in FIG. 7). In the high temperature region 41F, the temperature is the Curie temperature Tc12 (220
° C), the magnetization of the reproducing intermediate film 12 has disappeared (Fig. 7).

As described above, in the magneto-optical disk 10, only the medium temperature region 41E of the three regions 41D to 41F in the beam spot 41A has the reproducing film 11 and the reproducing intermediate film 1.
Both magnetizations are in a perpendicular magnetization state. Therefore, the magnetization that is stably held in the state as recorded in the memory film 13 having the layered structure is the beam spot 4
Only in the middle temperature region 41E in 1A, the transfer is performed in the order of the reproduction intermediate film 12 → the reproduction film 11. That is, the magnetization of the reproducing intermediate film 12 and the magnetization of the reproducing film 11 in the medium temperature region 41E are changed by the exchange coupling force from the memory film 13 to the memory film 1.
3 has the same direction as the magnetization. As a result, a perpendicular magnetization region corresponding to the magnetization direction of the memory film 13 is formed in the medium temperature region 41E of the reproduction film 11.

Here, the size of the intermediate temperature region 41E depends on the composition (Gd30Fe70) of the reproducing intermediate film 12, the reproducing power (3.5 mW), and the rotational speed of the disk (9 m / sec).
c) is determined by the relationship in FIG.
A plurality of small recording marks 13A formed at μm intervals,
13A,... (Each mark length is 0.3 μm).

For this reason, the 1
Only one recording mark 13A is in the intermediate temperature region 41E, and the reproduction intermediate film 12 (transfer mark 12A) → the reproduction film 11
(Transfer mark 11A).

In the low temperature region 41D, the exchange coupling force from the memory film 13 does not directly act on the reproduction film 11 due to the in-plane magnetization state of the reproduction intermediate film 12, and the magnetization of the memory film 13 is Not transferred to (low temperature mask). At this time, the reproduction film 11 in the low temperature region 41D is
Under the influence of the applied reproducing magnetic field Hr, the magnetization is uniformly aligned in the erasing direction (downward in FIG. 7).

In the high temperature region 41F, the magnetic coupling between the memory film 13 and the reproducing film 11 is interrupted by the above-mentioned demagnetized state of the reproducing intermediate film 12.
The magnetization of the memory film 13 is not transferred to the reproduction film 11 (high-temperature mask). At this time, the regenerated film 11 in the high temperature region 41F
As in the case of the low-temperature region 41D, the magnetization is uniformly aligned in the erasing direction (downward in FIG. 7) under the influence of the applied reproducing magnetic field Hr.

The reproducing magnetic field H applied at this time is
r is a relatively weak magnetic field that does not affect the transfer of the mark in the medium temperature region 41E (100
(Oe)). As described above, in the magneto-optical disk 10, one transfer mark 11A (magnetization is in the recording direction) is formed only in the middle temperature region 41E in the beam spot 41A, and a double mask (magnetization is one) is formed in the low temperature region 41D and the high temperature region 41F. The erase direction is formed in the same manner. Therefore, by detecting the component (reflected beam) of the reproduction beam 41 reflected by the beam spot 41A, the memory film 13 having a layered structure is detected.
, A plurality of small recording marks 13A, 13A,
, And only one of them is D
-Can be reproduced by the RAD method.

The above-described reproducing operation is sequentially performed in the disk moving direction 10A with the rotation of the magneto-optical disk 10, whereby a plurality of small recording marks 13A held in the memory film 13 having a layer structure of the magneto-optical disk 10 are obtained. ,
13A,... Can be sequentially reproduced one by one.

In this rewritable magneto-optical disk 10, a recording mark having a mark length of 0.3 μm was actually recorded at a distance between marks of 0.3 μm, and a carrier-to-noise intensity ratio (CN
As a result, it was found that a good CN ratio of 47.5 dB or more, which is a practical level (45 dB) or more, was obtained. As described above, in the rewritable magneto-optical disk 10 according to the first embodiment, the structure of the memory film 13 is a layered structure in which two alloy layers 13-1 and 13-2 having different compositions are stacked. Without extremely strictly controlling the power of the beam 31, the recording mark 13A sufficiently smaller than the beam spot 31A can be stably and surely written.
3A can be accurately reproduced by the D-RAD method while being stably held.

Therefore, according to the rewritable magneto-optical disk 10 of the first embodiment, a plurality of small recording marks 1
It is possible to obtain a high-density magneto-optical disk suitable for recording and reproducing information composed of 3A, 13A,. In the first embodiment, the rewritable magneto-optical disk 10
The memory film 13 of FIG. 2 has a layer structure in which a basic layer 13a composed of an RE-rich alloy layer 13-1 and a TM-rich alloy layer 13-2 is repeatedly laminated (FIG. 2). As shown in FIG. 9, the film 13 may have a two-layer structure including an RE-rich alloy layer 13-1 and a TM-rich alloy layer 13-2.

In the first embodiment, in the memory film 13 of the magneto-optical disk 10, the RE-rich alloy layer 13
-1 and the thickness D2 of the TM-rich alloy layer 13-2 are both 2 nm.
2 can be set to any value within a range greater than 0.5 nm and less than 50 nm. In this case, the thicknesses D1 and D2 of the alloy layers 13-1 and 13-2 may be different. Incidentally, the thickness D of each of the alloy layers 13-1 and 13-2 described above.
1, the minimum value of D2 (0.5 nm) is determined for each alloy layer 13-1,
This corresponds to the thickness of one atom constituting 13-2.

Further, in the first embodiment, in the memory film 13 of the magneto-optical disk 10, the RE-rich alloy layer 1
Although the example in which the ratio of Tb constituting 3-1 is 21 atomic% has been described, the ratio of Tb in the RE-rich alloy layer 13-1 is 20 atomic%.
It can be set to any value within the range greater than atomic% and less than 25 atomic%. In the first embodiment, the memory film 13 of the magneto-optical disk 10
The example in which the ratio of Tb constituting the M-rich alloy layer 13-2 is 19 atomic% has been described.
The ratio of b can be set to any value within the range of more than 15 atomic% and less than 20 atomic%.

Further, in the first embodiment, the example in which the memory film 13 having the layer structure is constituted by the RE-rich alloy layer 13-1 and the TM-rich alloy layer 13-2 has been described. And two alloy layers in which the ratio of constituent elements is different but the sub-lattice magnetization of the rare earth metal is dominant, or two alloy layers in which the ratios of the constituent elements are different but the sub-lattice magnetization of the transition metal are both dominant. You can also.

In the first embodiment, the D-RAD type magneto-optical disk 10 in which an in-plane magnetization film (reproduction intermediate film 12) is formed between the reproduction film 11 and the memory film 13 has been described as an example. A FAD type magneto-optical disk in which a perpendicular magnetization film is formed between the reproduction film 11 and the memory film 13 or a non-magnetic film or paramagnetic film between the reproduction film 11 and the memory film 13; In the formed magnetostatic coupling type magneto-optical disk (Claim 10), the memory film may have a layered structure.

Further, in the first embodiment, the example of the magneto-optical disk 10 in which a plurality of functional films (reproducing film 11, reproducing intermediate film 12, and memory film 13) are formed on the substrate 21 has been described. In a magneto-optical disk having a functional film (memory film) formed on a substrate (claim 6), the memory film may have a layered structure. In the first embodiment,
Although the example has been described in which only the memory film 13 of the rewritable magneto-optical disk 10 has a layered structure, the reproduction intermediate film 12 and the reproduction film 1 related to the operation of reproducing the information recorded in the memory film 13 are described.
1 may have a layered structure.

Further, in the first embodiment, an example of using the pen tip recording method to record information at a high density on the memory film 13 of the magneto-optical disk 10 has been described, but the magnetic field modulation recording method may be used. it can. However, even when the magnetic field modulation recording method is used, information can be recorded on the memory film 13 at a high density.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. This second embodiment corresponds to claims 1 to 8, and claims 11 to 14. The magneto-optical disk 60 according to the second embodiment is a magneto-optical disk of a light modulation direct overwrite recording method (hereinafter, referred to as a “LIMDOW recording method”), and a protective film is formed on a substrate 71 from the upper side to the lower side in FIG. 72, a reproducing film 61, a reproducing intermediate film 62, a cutting film 63, a memory film 64, an intermediate film 65, a recording film 66,
The switching film 67, the initialization film 68, the protection film 73, the metal film 74, and the resin protection film 75 are sequentially formed.

The memory film 64 (claims 6 to 8)
Is a film for retaining recorded information, similarly to the memory film 13 of the rewritable magneto-optical disk 10 of the first embodiment. Also, a reproducing film 61 (corresponding to the second functional film of claims 7 and 8), a reproducing intermediate film 62 (corresponding to the third functional film of claim 8),
Cutting film 63 (corresponding to the eighth functional film of claim 14)
Is a rewritable magneto-optical disk 10 according to the first embodiment.
D-RAD of information recorded on the memory film 64
This is a film that performs a reproducing operation by the method.

Further, the intermediate film 65 (corresponding to the sixth functional film of claim 12), the recording film 66 (corresponding to the fourth functional film of claim 11), the switching film 67 (corresponding to the 13th functional film of claim 13). 7), an initialization film 68 (claim 11).
Is a film for performing an overwrite recording operation of information on the memory film 64.

Here, each of the films 61 to 68, constituting the magneto-optical disk 60 of the LIMDOW recording system of the second embodiment,
The composition, film thickness and function of 72 to 75 will be described individually. The reproducing film 61 is a magnetic film of one composition composed of a uniform alloy of Gd as a rare earth metal and Fe and Co as transition metals. The specific composition of the reproducing film 61 is Gd25Fe60Co15, and the film thickness D61 is 30 nm.

The reproduction film 61 having such a composition and thickness is as follows.
Is a perpendicular magnetization film in which the magnetization is oriented perpendicular to the film surface (vertical direction in FIG. 10). In addition, the Curie temperature Tc61 of the reproducing film 61 is set to at least a reproducing intermediate film 62 described later.
Curie temperature Tc62 (220 ° C.). Also,
The reproduction intermediate film 62 is a magnetic film of one composition composed of a uniform alloy of Gd which is a rare earth metal and Fe which is a transition metal. The specific composition of the reproduction intermediate film 62 is G
d29Fe71, and the film thickness D62 is 50 nm.

The reproduced intermediate film 6 having such composition and film thickness
Reference numeral 2 denotes an in-plane magnetized film whose magnetization is oriented in-plane (horizontally in FIG. 10) at room temperature Tr. Further, the reproduced intermediate film 62
Is a predetermined temperature Tx higher than the room temperature Tr (around 110 ° C.)
The magnetization changes from the in-plane magnetization state to the perpendicular magnetization state. Further, the Curie temperature Tc62 of the reproduced intermediate film 62
Is higher than the predetermined temperature Tx (110 ° C.)
It is about 20 ° C.

The cutting film 63 is made of T which is a rare earth metal.
This is a magnetic film of one composition composed of a uniform alloy of b and a transition metal, Fe. The specific composition of the cut film 63 is Tb20Fe80, and the film thickness D63 is 20 nm. The cut film 63 having such a composition and thickness is a perpendicular magnetization film similarly to the reproduction film 61, and has a Curie temperature Tc63 of about 140 ° C. This Curie temperature Tc
63 (140 ° C.) is lower than the Curie temperature Tc 62 (220 ° C.) of the reproduction intermediate film 62 and the Curie temperature Tc 64 (180 ° C.) of the memory film 64 described later. Further, the Curie temperature Tc63 (140 ° C.) is higher than the predetermined temperature Tx (110 ° C.) of the reproduced intermediate film 62 described above.

The memory film 64 is a magnetic film composed of Tb, which is a rare earth metal, and Fe, Co, which are transition metals. Like the memory film 13 of the first embodiment, the memory film 64 is composed of two alloys having different compositions. It has a layer structure (multilayer) in which layers are repeatedly laminated (FIG. 2). One alloy layer forming the memory film 64 having such a layer structure is the RE-rich alloy layer 1 forming the memory film 13 of the first embodiment.
Like 3-1, the layer is a layer in which the sublattice magnetization of the rare earth metal is dominant (corresponding to the first layer in claims 1 to 7), and its specific composition is Tb21Fe71.1Co7.9 (the thickness is 2 nm).

The other alloy layer forming the memory film 64 having the layer structure has the same transition metal sublattice magnetization as the TM rich alloy layer 13-2 forming the memory film 13 of the first embodiment. (Corresponding to the first layer of claims 1 to 7), and its specific composition is Tb19Fe72.9Co8.1 (the thickness is 2 nm). Note that the memory film 64 having a layered structure in which the RE-rich alloy layer and the TM-rich alloy layer having such compositions and thicknesses are stacked is a perpendicular magnetization film in which the magnetization is oriented perpendicular to the film surface. Also, the memory film 64
Has a Curie temperature Tc of 35 nm.
64 is about 180 ° C.

The intermediate film 65 is made of G which is a rare earth metal.
It is a magnetic film of one composition (in-plane magnetized film at room temperature Tr by itself) composed of a uniform alloy of d and transition metals Fe and Co. The specific composition of the intermediate film 65 is Gd
32Fe64Co4, and the film thickness D65 is 10 nm. Since the intermediate film 65 has the above composition, it has almost no coercive force.

The recording film 66 is a magnetic film of one composition (perpendicular magnetization film) composed of a uniform alloy of dysprosium (Dy) as a rare earth metal and Fe and Co as transition metals. The specific composition of the recording film 66 is Dy26
Fe44Co30, and the film thickness D66 is 20 nm. The recording film 66 has a compensation temperature Th66 at room temperature T.
This is a film between r and the Curie temperature Tc66. In addition,
The Curie temperature Tc66 of the recording film 66 is at least the Curie temperature Tc64 (180 ° C.) of the memory film 64,
It is higher than the Curie temperature Tc67 of the switching film 67 described later.

The switching film 67 is a magnetic film (perpendicular magnetization film) of one composition made of a uniform alloy of Tb as a rare earth metal and Fe and Co as transition metals. The specific composition of the switching film 67 is Tb17
Fe77Co6, and the film thickness D67 is 12 nm. The switching film 67 has a Curie temperature Tc.
67 is lower than the Curie temperature Tc66 of the recording film 66 and the Curie temperature Tc68 of the initialization film 68 described later.

The initialization film 68 is a magnetic film (perpendicular magnetization film) of one composition made of a uniform alloy of Tb which is a rare earth metal and Fe and Co which are transition metals. The specific composition of the initialization film 68 is Tb20Fe16Co64.
And the film thickness D68 is 20 nm. The initialization film 68 has a Curie temperature Tc68 higher than the above-described Curie temperature Tc66 of the recording film 66, and has a high coercive force.

The protective films 72 and 73 for protecting the above-described films 61 to 68 are made of silicon nitride, and have a thickness D72 of 70 nm and a thickness D73 of 30 nm. The metal film 74 is a film for adjusting the recording sensitivity, and has a film thickness D
74 is a 30 nm aluminum thin film. In addition, the resin protective film 75 is formed of each of the above films 61 deposited on the substrate 71.
To 68, 72 to 74. The substrate 71 is a polycarbonate substrate (90 mm in diameter) in which guide grooves are formed in a spiral shape.

Incidentally, among the films 61 to 68 described above, the formation of the memory film 64 having a layered structure is described in the first embodiment.
Similar to the formation of the memory film 13 of the embodiment, the formation is performed in a synchronous sputtering apparatus in which an alloy target for the RE-rich alloy layer and an alloy target for the TM-rich alloy layer are separately arranged. Further, the film formation of the other films 61 to 63 and 65 to 68 is the same as the reproduction film 11 of the first embodiment described above.
As in the case of the regeneration intermediate film 12, the film formation is performed in a single-wafer sputtering apparatus.

In the magneto-optical disk 60 of the LIMDOW recording system configured as described above, overwriting of information on the memory film 64 having a layer structure is performed as follows. First, in overwriting information,
The magneto-optical disk 60 is continuously irradiated with a recording beam (having a wavelength of 680 nm) from a recording / reproducing device (not shown). Information is written by modulating the recording power at this time (high level / low level). In the overwrite recording, a recording magnetic field (recording direction) of a certain magnitude is applied to the beam spot (1.1 μm) of the recording beam. The direction of the recording magnetic field is determined by the initialization film 6.
8 is opposite to the magnetization direction (erase direction). At the time of overwrite recording, the magneto-optical disk 60 is rotated at a constant linear velocity (for example, 9 m / sec) by a motor.

When the recording power is at a high level, only a part (heating area) within the beam spot (1.1 μm) is heated at least higher than the Curie temperature Tc 66 of the recording film 66, and the recording film 66 and the memory film are heated. 64, the magnetization of the switching film 67 temporarily disappears. Thereafter, when the above-mentioned heating region deviates from the beam spot and its temperature gradually decreases toward room temperature Tr, the magnetization of the recording film 66 recovers,
The magnetization direction follows the recording magnetic field (recording direction).

When the temperature further decreases, the recording film 66
Is then transferred to the memory film 64 where the magnetization is recovered, where it is retained (the magnetization is in the recording direction). In this way, the recording mark (the magnetic domain in the recording direction, the mark length of 0.3) is smaller than the beam spot (1.1 μm) temporarily written on the recording film 66 by the recording magnetic field.
μm) is transferred and held on the memory film 64.

After the magnetization is transferred from the recording film 66 to the memory film 64, if the temperature further decreases, the initialization film 68
By this operation, the magnetization direction of the recording film 66 is forcibly aligned in one direction, and the recording film 66 is initialized (the magnetization is in the erasing direction). When the recording film 66 is initialized, the memory film 6
The magnetization of No. 4 is maintained in the recording direction without being initialized integrally with the recording film 66. This is because the function of the intermediate film 65 provided between the recording film 66 and the memory film 64 causes the recording film 66 to be initialized when the recording film 66 is initialized.
This is because the magnetic coupling force between the semiconductor device and the memory film 64 is weakened.

The magnetic coupling force from the initialization film 68 to the recording film 66 is applied to the recording film 66 by the recording magnetic field by the action of the switching film 67 provided between the initialization film 68 and the recording film 66. The information is temporarily weakened when information is written, and is transmitted only when the recording film 66 is initialized. By irradiating a high-level recording beam in this manner, a beam spot (1.1
μm), one recording mark (magnetic domain whose magnetization is in the recording direction, mark length 0.3 μm)
Can be overwritten.

Here, in the overwrite recording of the recording mark smaller than the beam spot as described above, similarly to the first embodiment, the irradiation time of the high-level recording beam is shortened and the heating area is reduced. (Writing method). For this reason, the size of the heating region tends to vary due to the temporal fluctuation (noise) of the high-level recording power.

However, in the magneto-optical disk 60 of the second embodiment, as in the first embodiment, the memory film 64
Instead of an alloy film having one composition, the film has a layered structure in which RE-rich alloy layers and TM-rich alloy layers having different compositions are stacked. Therefore, the recording power margin of the memory film 64 is larger than that of the memory film composed of an alloy film having one composition.

As described above, in the memory film 64 having a layer structure in which the recording power margin is enlarged, the beam spot (1.
Even if the size of the heating region smaller than 1 μm) varies, it is possible to stably overwrite the recording mark (magnetization direction) of a fixed size (0.3 μm).

On the other hand, when the recording power is low, the temperature of a part of the area within the beam spot becomes higher than the Curie temperature Tc 64 (180 ° C.) of the memory film 64, but becomes lower than the Curie temperature Tc 66 of the recording film 66. Does not reach. Therefore, although the magnetization of the memory film 64 temporarily disappears, the recording film 6
6 remains in the initialized state (the magnetization is in the erasing direction). Thereafter, when the temperature gradually decreases toward the room temperature Tr, the magnetization of the memory film 64 recovers, and the magnetization direction follows the magnetization (erasing direction) of the recording film 66. When the temperature reaches the room temperature Tr, the magnetization of the memory film 64 is maintained while following the initialized recording film 66.

By irradiating a low-level recording beam in this way, a recording mark can be erased in a part of the area smaller than the beam spot. Accordingly, by irradiating the magneto-optical disk 60 with a recording beam while modulating the power (high level / low level) in accordance with the information to be recorded, the beam spot (regardless of the recorded marks already recorded) is obtained. Recording marks (0.3 μm) smaller than 1.1 μm) can successively be overwritten on the memory film 64 having a layered structure (distance between marks 0.3 μm), and reliably record high-density information. it can.

Next, the operation of reproducing information using the D-RAD method on the magneto-optical disk 60 of the LIMDOW recording method in which high-density information is recorded on the memory film 64 having a layer structure as described above will be described. I do. In FIG. 11 for explaining the reproducing operation, the directions of the magnetizations of the films 61 to 64 are indicated by arrows.

When reproducing information, the magneto-optical disk 6
0 is irradiated with a reproducing beam 81 of constant power from a semiconductor laser of a recording / reproducing apparatus (not shown) (FIG. 11).
In this case, the power of the reproducing beam 81 is set to a value (for example, 2 mW) smaller than the power (3.5 mW) of the reproducing beam 41 in the magneto-optical disk 10 of the first embodiment. The reproducing beam 81 is also applied to the magneto-optical disk 60 in a state of linearly polarized light.

In reproducing information, the beam spot 81A of the reproduction beam 81 has a reproduction magnetic field Hr (for example, 100 (Oe)) of a constant magnitude generated from a magnetic coil of a recording / reproducing apparatus (not shown). Is applied (FIG. 1
1). The direction of the reproducing magnetic field Hr is opposite to the direction of the recording magnetic field (recording direction) (erasing direction). Further, in reproducing the information, the magneto-optical disk 60 is rotated at the same linear velocity (for example, 9 m / sec) as the above-described recording, and the disk moving direction 60A (the left direction indicated by an arrow in FIGS. 11 and 12). On the other hand, it moves while crossing the beam spot 81A.

When the reproduction beam 81 is actually irradiated, the first beam spot 81A on the magneto-optical disk 60
As in the case of the magneto-optical disk 10 of the embodiment, a temperature distribution is generated in which the temperature gradually decreases from the front to the rear in the moving direction 60A (from left to right in FIGS. 11 and 12). Here, the inside of the beam spot 71A is divided into three regions having different temperatures (a high temperature region 81F, a medium temperature region 81E,
The low-temperature region 81D) will be considered separately.

In the second embodiment, the Curie temperature Tc64 (1) of the memory film 64 in the high-temperature region 81F is irradiated by the irradiation of the reproduction beam 81 of low power (2 mW).
80 ° C.) and the Curie temperature Tc 63 of the cut film 63
(140 ° C.). In addition, medium temperature area 8
In 1E, the Curie temperature Tc63 of the cut film 63 (140
° C) and a predetermined temperature Tx (11
0 ° C.). Further, the low-temperature region 81D
In this case, the temperature is lower than the predetermined temperature Tx (110 ° C.) of the reproducing intermediate film 62 and higher than the room temperature Tr.

As described above, three regions 81 having different temperatures are used.
Beam spot 81A divided into D, 81E and 81F
Within each of the films 61 to 61 constituting the magneto-optical disk 60,
Each of the 64 magnetizations is in the state described below. First,
The magnetization of the memory film 64 will be described. The temperature in the beam spot 81A is the Curie temperature Tc64 (180 ° C.) of the memory film 64 in any of the regions 81D to 81F.
Lower than the temperature at which the magnetization of the memory film 64 is maintained in the perpendicular magnetization state.

Further, the memory film 64 of the second embodiment
Has a layered structure in which two alloy layers having different compositions are stacked instead of an alloy film having a single composition as described above, and thus has a wide temperature range (beam) as in the memory film 13 of the first embodiment. Over the entire temperature range within the spot 81A), the coercive force is sufficiently increased to hold information.

Therefore, the recording mark 64A (magnetic domain whose magnetization is in the recording direction) written in the memory film 64 having a layer structure.
Indicates that the size (0.3 μm) of the beam spot 81
A (1.1 μm), even if the area is very small, the small recording mark 64A is not affected by the surroundings in the opposite magnetization direction (erasing direction), and the beam spot 81A is not affected. All areas 81D to 8 in
The state as recorded in 1F is stably maintained.

On the other hand, the magnetization of the reproducing film 61 related to the operation of reproducing the information held in the memory film 64 is maintained in the perpendicular magnetization state in any of the regions 81D to 81F in the beam spot 81A. This is beam spot 8
This is because the highest temperature in 1A (the temperature of the high-temperature region 81F) is lower than the Curie temperature Tc61 of the reproduction film 61.

Further, like the reproduction film 61, the memory film 64
The magnetization of the reproduction intermediate film 62 involved in the operation of reproducing the information in the low temperature region 81D (when the temperature is the predetermined temperature Tx of the reproduction intermediate film 62)
(Lower than 110 ° C.), the in-plane magnetization state (FIG. 11)
(Medium, horizontal direction) (FIG. 11). Further, in the middle temperature region 81E and the high temperature region 81F, the temperatures are lower than the Curie temperature Tc62 (220 ° C.) of the reproduction intermediate film 62 and higher than the predetermined temperature Tx (110 ° C.) of the reproduction intermediate film 62. The magnetization of 62 changes from the in-plane magnetization state to a perpendicular magnetization state (vertical direction in FIG. 11).

Similarly to the reproducing film 61 and the reproducing intermediate film 62, the cutting film 6 relating to the information reproducing operation of the memory film 64 is used.
In the low temperature region 81D and the medium temperature region 81E (the temperature is lower than the Curie temperature Tc63 (140 ° C.) of the cut film 63), the magnetization of No. 3 is maintained in the perpendicular magnetization state without disappearing (FIG. 11). In the high temperature region 81F,
That temperature is the Curie temperature Tc63 (140
° C), the magnetization of the cut film 63 has disappeared (Fig. 11).

As described above, in the magneto-optical disk 60, of the three regions 81D to 81F in the beam spot 81A, the reproducing film 61 and the reproducing intermediate film 6 are formed only in the medium temperature region 81E.
2. The magnetization of the cutting film 63 is all in a perpendicular magnetization state. Therefore, the magnetization stably held in the memory film 64 having a layer structure is transferred in the order of the cutting film 63 → the reproducing intermediate film 62 → the reproducing film 61 only in the middle temperature region 81E in the beam spot 81A. That is, the magnetizations of the cut film 63, the intermediate reproduction film 62, and the reproduction film 61 in the middle temperature region 81E have the same direction as the magnetization of the memory film 64 due to the exchange coupling force from the memory film 64. As a result, the reproduction film 6
A perpendicular magnetization region corresponding to the magnetization direction of the memory film 64 is formed in one medium temperature region 81E.

Here, the size of the intermediate temperature region 81E depends on the composition of the reproducing intermediate film 62 (Gd30Fe70), the composition of the cut film 63 (Tb20Fe80), the reproducing power (2 mW),
One of a plurality of small recording marks 64A, 64A,... Formed on the memory film 64 at intervals of 0.3 μm is determined by the relationship of the rotation speed of the disk (9 m / sec).
It is said that only one can enter.

For this reason, the 1
Only one recording mark 64A is in the middle temperature region 81E, and the cutting film 63 (transfer mark 63A) → the reproducing intermediate film 62.
(Transfer mark 62A) → reproduction film 61 (transfer mark 61)
A) is sequentially transferred. Note that the low temperature region 81
In D, the exchange coupling force from the memory film 64 and the cut film 63 does not directly act on the reproducing film 61 due to the above-mentioned in-plane magnetization state of the reproducing intermediate film 62, so that the magnetization of the memory film 64 is transferred to the reproducing film 61. Not performed (low temperature mask). At this time, the reproduction film 61 in the low temperature region 81D is in a state where its magnetization is uniformly aligned in the erasing direction (downward in FIG. 11) under the influence of the applied reproduction magnetic field Hr.

In the high-temperature region 81F, the magnetic coupling between the memory film 64 and the reproducing intermediate film 62 is interrupted by the magnetization disappearing state of the cutting film 63.
The magnetization of the memory film 64 is not transferred to the reproduction film 61 (high-temperature mask). At this time, the reproduction film 61 in the high temperature region 81F
As in the case of the low-temperature region 81D described above, the magnetization is uniformly aligned in the erasing direction (downward in FIG. 11) under the influence of the applied reproducing magnetic field Hr.

The reproducing magnetic field H applied at this time is
r is a relatively weak magnetic field that does not affect the transfer of the mark in the medium temperature region 81E (100
(Oe)). As described above, in the magneto-optical disk 60, one transfer mark 61A (the magnetization direction is the recording direction) is formed only in the middle temperature region 81E in the beam spot 81A, and the double mask (the magnetization is one) in the low temperature region 81D and the high temperature region 81F. The erase direction is formed in the same manner. Therefore, by detecting the reproduction beam 81 component (reflected beam) reflected by the beam spot 81A, the memory film 64 having a layered structure is detected.
, A plurality of small recording marks 64A, 64A,
, And only one of them is D
-Can be reproduced by the RAD method.

The above-described reproducing operation is sequentially performed in the disk moving direction 60A with the rotation of the magneto-optical disk 60, whereby a plurality of small recording marks 64A held in the memory film 64 having a layer structure of the magneto-optical disk 60 are obtained. ,
64A,... Can be sequentially reproduced one by one. Actually, a recording mark having a mark length of 0.3 μm is recorded at a distance between marks of 0.3 μm on the magneto-optical disk 60 of the LIMDOW recording method, and a carrier to noise intensity ratio (CN ratio) is recorded.
It was found that a good CN ratio of 47.5 dB or more, which is a practical level (45 dB) or more, was obtained.

As described above, the LI of the second embodiment
In the magneto-optical disk 60 of the MDOW recording method, the structure of the memory film 64 is a layered structure in which two alloy layers having different compositions are stacked. A sufficiently small recording mark 64A can be stably and reliably written, and accurate reproduction can be performed by the D-RAD method while maintaining such a small recording mark 64A stably.

Therefore, the LIMDOW of the second embodiment
According to the magneto-optical disk 60 of the recording system, it is possible to obtain a high-density magneto-optical disk suitable for recording and reproducing information including a plurality of small recording marks 64A. Furthermore, according to the magneto-optical disk 60 of the LIMDOW recording system of the second embodiment, the cutting film 63 (perpendicular magnetization film; T) between the memory film 64 and the reproducing intermediate film 62.
c62, Tc64>Tc63> Tx), it is possible to secure a wide high-temperature region 81F for masking high-density information of the memory film 64 even if the power of the reproduction beam 81 is small, and the D-RAD method Accurate reproduction can be reliably performed.

According to the magneto-optical disk 60 of the LIMDOW recording system of the second embodiment, the power of the recording beam is modulated (high level / low level) according to the information to be recorded.
By simply doing so, it is possible to erase the already recorded recording mark or write a new recording mark, so that the speed of the information recording operation can be increased.

In the second embodiment, an example has been described in which the memory film 64 of the magneto-optical disk 60 has a layer structure (multilayer) in which an RE-rich alloy layer and a TM-rich alloy layer are repeatedly laminated. , This memory film 64 also
Similarly to the memory film 13 of the first embodiment, a two-layer structure including an RE-rich alloy layer and a TM-rich alloy layer may be employed.

In the second embodiment, in the memory film 64 of the magneto-optical disk 60, the RE-rich alloy layer, T
Although the example in which the thicknesses of the M-rich alloy layers are both 2 nm has been described, these thicknesses may be arbitrary within a range larger than 0.5 nm and smaller than 50 nm, as in the memory film 13 of the first embodiment. Can be set to a value. Further, in the second embodiment, the example in which the ratio of Tb constituting the RE-rich alloy layer is 21 atomic% in the memory film 64 of the magneto-optical disk 60, but the ratio of Tb in the RE-rich alloy layer is: It can be set to any value within the range of more than 20 at% and less than 25 at%.

In the second embodiment, the example in which the ratio of Tb constituting the TM rich alloy layer is 19 atomic% in the memory film 64 of the magneto-optical disk 60 has been described.
The ratio of Tb in the TM-rich alloy layer can be set to any value within a range of more than 15 atomic% and less than 20 atomic%. Further, in the second embodiment, the example in which the memory film 64 having the layer structure is configured by the RE-rich alloy layer and the TM-rich alloy layer has been described. Two alloy layers in which the sub-lattice magnetization of the rare earth metal is dominant, or two alloy layers in which the sub-lattice magnetization of the transition metal is dominant but the ratios of the constituent elements are different from each other can be used.

In the second embodiment, the D-RAD type magneto-optical disk 60 in which an in-plane magnetization film (reproduction intermediate film 62) is formed between the reproduction film 61 and the memory film 64 has been described as an example. A magneto-optical disk of the FAD type in which a perpendicular magnetization film is formed between the reproducing film 61 and the memory film 64, or a non-magnetic film or a paramagnetic film between the reproducing film 61 and the memory film 64. In the formed magnetostatic coupling type magneto-optical disk (Claim 10), the memory film may have a layered structure.

Further, in the second embodiment, LIMDOW
Although the example in which only the memory film 64 of the recording type magneto-optical disk 60 has a layer structure has been described, the cutting film 63 and the reproducing intermediate film 6 related to the operation of reproducing the information recorded in the memory film 64 are described.
2. The intermediate film 65, the recording film 66, the switching film 67, and the initialization film 68 related to the overwrite recording operation of information on the reproduction film 61 and the memory film 64 may have a layered structure.

In the second embodiment, the example in which the recording film 66 of the magneto-optical disk 60 is made of DyFeCo has been described. However, this recording film 66 can be made of GdTbFeCo. Thus, the recording film 66 is formed of GdTbFeCo.
When forming the recording film 66 into a layered structure, two alloy layers (GdFe
(Co alloy layer, TbFeCo alloy layer).

In the second embodiment, the example in which the intermediate film 65 is formed between the recording film 66 and the memory film 64 has been described. However, by adjusting the compositions of the recording film 66 and the memory film 64 themselves, When the recording film 66 is initialized, the memory film 6
The intermediate film 65 may not be provided as long as the magnetization of No. 4 can be prevented from being initialized integrally with the recording film 66.

Further, in the second embodiment, the initialization film 68
Although the example in which the switching film 67 is formed between the recording film 66 and the recording film 66 has been described, information on the recording film 66 is temporarily recorded by adjusting the composition of the initialization film 68 and the recording film 66 itself. When the recording film 6
The switching film 67 may not be provided as long as the magnetic coupling force to the switching film 6 can be weakened.

In the second embodiment, an example in which the pen tip recording method is used to record information at a high density on the memory film 64 of the magneto-optical disk 60 has been described.
As in the embodiment, a magnetic field modulation recording method can be used. Furthermore, in the above-described embodiment, a magneto-optical disk has been described as an example, but each functional film constituting the phase change disk may have a layered structure.

[0138]

As described above, claims 1 to 1 are provided.
According to the optical recording medium described in No. 4, at least one structure of one or more functional films that contribute to recording and reproduction of information has a layer structure in which two alloy layers having different compositions are stacked.
Without very tightly controlling the power of the recording beam,
A recording mark sufficiently smaller than the beam spot can be stably and reliably written, and reproduction can be performed while such a small recording mark is stably held.

Therefore, it is possible to obtain an optical recording medium in which information composed of a plurality of recording marks smaller than the beam spot has been increased in density and the reliability in recording and reproducing high-density information has been enhanced.

[Brief description of the drawings]

FIG. 1 is a rewritable magneto-optical disk 10 according to a first embodiment.
It is sectional drawing which shows a structure of.

FIG. 2 is a cross-sectional view illustrating a memory film 13 having a layer structure.

FIG. 3 is an explanatory view showing a configuration of a simultaneous sputtering apparatus 50 for forming a memory film 13 having a layer structure.

FIG. 4 is a cross-sectional view illustrating an operation of recording information on a memory film 13.

FIG. 5 is a top view for explaining an operation of recording information on a memory film 13;

FIG. 6 is a diagram for explaining an enlargement of a recording power margin in the memory film 13 having a layer structure.

FIG. 7 is a cross-sectional view illustrating an operation of reproducing information recorded on a memory film 13;

FIG. 8 is a top view for explaining an operation of reproducing information recorded on the memory film 13;

FIG. 9 is a cross-sectional view illustrating another configuration of the memory film 13 having a layer structure.

FIG. 10 is a cross-sectional view showing a configuration of a magneto-optical disk 60 of the second embodiment using the LIMDOW recording method.

FIG. 11 is a cross-sectional view illustrating a reproducing operation of information recorded on a memory film 64.

FIG. 12 is a top view for explaining an operation of reproducing information recorded in a memory film 64;

[Explanation of symbols]

 10, 60 Magneto-optical disk 11, 61 Reproduced film 11A, 12A, 61A, 62A, 63A Transfer mark 12, 62 Reproduced intermediate film 13, 64 Memory film 13A, 64A Record mark 13B Heated area 21, 71 Substrate 22, 23, 72 , 73 Protective film 31A, 41A, 81A Beam spot 41F, 81F High temperature region 41E, 81E Medium temperature region 41D, 81D Low temperature region 63 Cutting film 65 Intermediate film 66 Recording film 67 Switching film 68 Initialization film 74 Metal layer 75 Resin protection layer

Claims (14)

[Claims] 1. An optical recording medium having at least one functional film contributing to recording and reproduction of information formed on a substrate, wherein at least one of the one or more functional films is made of an alloy having a predetermined composition. An optical recording medium comprising a functional film having a layered structure in which a first layer and a second layer made of an alloy having a composition different from that of the first layer are stacked adjacent to each other. 2. The optical recording medium according to claim 1, wherein the functional film having the layer structure is formed by repeatedly laminating a basic layer including the first layer and the second layer. Optical recording medium. 3. The optical recording medium according to claim 1, wherein each of the first layer and the second layer is a magnetic layer containing an alloy composed of a rare earth metal and a transition metal. An optical recording medium characterized by the above-mentioned. 4. The optical recording medium according to claim 3, wherein the rare earth metal forming the first layer and the rare earth metal forming the second layer have the same constituent element. An optical recording medium, wherein the transition metal constituting the second layer and the transition metal constituting the second layer have the same constituent element. 5. The optical recording medium according to claim 4, wherein the first layer has a predominant sub-lattice magnetization of a rare earth metal, and the second layer has a predominant sub-lattice magnetization of a transition metal. An optical recording medium characterized by the above-mentioned. 6. The optical recording medium according to claim 1, wherein at least a first functional film for retaining recorded information is formed on the substrate, and The optical recording medium according to claim 1, wherein the first functional film is a functional film having a layer structure in which the first layer and the second layer are stacked adjacent to each other. 7. The optical recording medium according to claim 1, wherein at least a first functional film for holding recorded information and a reproduction beam irradiation area are provided on the substrate. A second functional film in which a perpendicular magnetization region corresponding to the magnetization direction of the first functional film is formed in a partial region corresponding to a temperature distribution in the first functional film; , The first layer and the second layer
An optical recording medium, characterized in that the layer is a functional film having a layer structure laminated adjacently. 8. The optical recording medium according to claim 7, wherein a magnetization direction of the first functional film is set between the first functional film and the second functional film. Forming a third functional film to be transferred to the second functional film in the region, wherein the third functional film is an in-plane magnetized film, and has a temperature higher than a temperature at which the in-plane magnetized state changes to a perpendicular magnetized state. Is higher than the temperature at which the in-plane magnetization state of the third functional film changes to the perpendicular magnetization state in the reproduction beam irradiation area, and the Curie temperature of the third functional film. An optical recording medium, wherein an area at a lower temperature is the partial area. 9. The optical recording medium according to claim 7, wherein a magnetization direction of the first functional film is set between the first functional film and the second functional film. A third functional film to be transferred to the second functional film is formed in the region, the third functional film is a perpendicular magnetization film, and a Curie of the third functional film in the reproduction beam irradiation region. An optical recording medium, wherein an area lower than the temperature is the partial area. 10. The optical recording medium according to claim 7, wherein a nonmagnetic film or a paramagnetic film is formed between the first functional film and the second functional film. Optical recording medium. 11. The optical recording medium according to claim 6, wherein a perpendicular magnetization film is provided on a side of the first functional film opposite to the substrate, and the information is temporarily stored on the first functional film. A fourth functional film for recording and transferring the magnetization direction representing the information to the first functional film; and a perpendicular magnetic film, wherein the magnetization direction of the fourth functional film is applied to the first functional film. An optical recording medium, characterized in that, after the transfer, a fifth functional film for forcibly aligning the magnetization direction of the fourth functional film in one direction is sequentially formed. 12. The optical recording medium according to claim 11, wherein an in-plane magnetization film is provided between the first functional film and the fourth functional film, Optical recording, characterized in that a sixth functional film is formed, which weakens the magnetic coupling force from the fourth magnetic film to the first magnetic film when the magnetization direction is forcibly aligned in one direction. Medium. 13. The optical recording medium according to claim 11, wherein a perpendicular magnetization film is provided between the fourth functional film and the fifth functional film, and When information is temporarily recorded on the functional film, a seventh functional film for weakening a magnetic coupling force from the fifth functional film to the fourth functional film is formed. Optical recording medium. 14. The method according to claim 11, wherein
The optical recording medium according to claim 1, wherein a perpendicular magnetization film is provided between the first functional film and the third functional film, the Curie temperature of which is higher than the Curie temperature of the first functional film. An optical recording medium, wherein a low eighth functional film is formed.