JP2000076719A - Magneto-optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical disk which uses a DWDD (magnetic domain wall detection system) of high mass-productivity. SOLUTION: The magneto-optical disk B is constituted by successively laminating at least a recording layer 2 and a protective layer 3 on a transparent substrate 1, and performs the recording/reproducing of information by the use of the DWDD. The transparent substrate 1 is constituted by continuously forming minute track patterns in a spiral or concentric circular shape. The recording layer 2 is constituted by successively laminating at least a moving layer 2A, a switching layer 2B and a memory layer 2C on the transparent substrate 1. The tracks formed on the moving layer 2A are magnetically divided between adjacent tracks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DWDD (Dom
ain Wall DisplacementDete
ction, domain wall motion detection method).

[0002]

2. Description of the Related Art As one example of a magneto-optical disk capable of high-density recording and reproduction, a magneto-optical disk using DWDD is known.

FIG. 12 is a view for explaining a cross-sectional structure of a magneto-optical disk using DWDD, and FIG. 13 is a view for explaining DWDD. As shown in FIG. 12, a magneto-optical disk A using DWDD has at least a recording layer 2 and a protective layer 3 sequentially laminated on a plastic transparent substrate 1. The recording or reproducing laser beam L is applied to the recording layer 2 from the transparent substrate 1 side. The recording layer 2 includes a moving layer 2A exhibiting a small domain wall coercive force, a switching layer 2B having a relatively low Curie temperature, and a large domain wall coercive force in order from the irradiation side of the laser beam L (the transparent substrate 1 side). It is composed of a three-layer magnetic exchange coupling film composed of a memory layer 2C.

Recording and reproduction of the magneto-optical disk A having such a configuration are performed as shown in FIG. At the time of recording, FIG.
(A) An external magnetic field (not shown) for perpendicularly magnetizing in the opposite direction (upper direction in the figure) is applied to the magneto-optical disk A vertically magnetized in the lower direction in FIG. The recording layer 2 is locally irradiated with the laser beam L and heated. As a result, the portion heated by the recording laser beam L is shown in FIG.
The temperature gradient shown in FIG. 3 (B) occurs. When the irradiation of the recording laser beam L is completed, the moving layer 2A, the switching layer 2B,
A domain wall 2Aa penetrating through the memory layer 2C is generated, and the portion irradiated with the recording laser beam L is vertically magnetized (upward in the figure). The memory layer 2C stores this state. on the other hand,
At the time of reproduction, when the reproducing laser light L having a lower power than the recording laser light L is irradiated, the magnetic domain wall temperature of the moving layer 2A is located in a region where the temperature is lower than the temperature Ts (temperature region Tsa shown in FIG. 13B). In this case, since the magnetic exchange coupling between the memory layer 2C and the moving layer 2A acts on the entire recording layer 2 due to the magnetism of the switching layer 2B, domain wall motion of the moving layer 2A does not occur. However, when the domain wall 2Aa in the moving layer 2A reaches a region having a temperature higher than the temperature Ts (a temperature region Tsb shown in FIG. 13B) with the reproduction scanning of the magneto-optical disk A (scanning direction 1A). ,
Thereby, the magnetism of the switching layer 2B is lost, and the magnetic exchange coupling between the memory layer 2C and the moving layer 2A is cut off.
For this reason, only the domain wall 2Aa in the moving layer 2A alone is
It expands toward the peak temperature Tsc side. In this manner, each time the magnetic domain walls 2Aa formed in the memory layer 2C at intervals corresponding to the information signal reach the isothermal line of the temperature Ts or more with the reproduction scanning of the magneto-optical disk A, the moving layer 2A The moving domain wall 2Ab that moves is generated. When the reproduction scanning of the magneto-optical disk A is performed at a constant speed, a moving domain wall 2Ab that moves at a time interval corresponding to the spatial interval of the domain walls 2Aa recorded is generated. In this way, the information is enlarged and reproduced.

As described above, in the magneto-optical disk A using DWDD, the reproducing laser beam L is locally irradiated on the moving layer 2A, and the moving magnetic wall 2Ab is detected, thereby recording on the memory layer 2C. The reproduced information signal can be enlarged and reproduced. In other words, by utilizing the generation of the moving magnetic domain wall 2Ab to enlarge the magnetic domain in the moving layer 2A transferred from the memory layer 2C, the resolution of the optical system is originally determined by the conventional detection method using the magneto-optical system. This enables high-density reproduction at a resolution higher than the resolution regulated by the standard.

Although not shown here, optical tracking grooves, which are ordinary fine track patterns, are continuously formed spirally or concentrically on the transparent substrate 1 described above. Lands are formed between the grooves. The recording layer 2 is, for example, a super-resolution magneto-optical film typified by a three-layer stack of GdFeCr as the memory layer 2C / TbFeCr as the switching layer 2B / TbFeCoCr as the moving layer 2A. .

[0007]

The above-mentioned DWD will be described.
About D. National Institute of Electrical Engineers of Japan S. 10-25 (199
Since the details are described in 8), the detailed description is omitted, but the information can be recorded and reproduced on either the land or the groove. At this time, at least one of the land and the groove in the moving layer 2A is a magnetic region, and the other is a non-magnetic region or a region having different magnetic characteristics. An important point in realizing DWDD reproduction is that when both the land and the groove in the moving layer 2A are magnetic regions having the same magnetic characteristics, the intended super-resolution is not exhibited. Therefore, by using a recording / reproducing pickup, the non-recording track is continuously heated with a laser power much higher than the recording condition, so as to demagnetize the magnetic material or change the magnetic characteristics. In other words, magnetic separation is performed between adjacent tracks.

Conventionally, magnetic separation between adjacent tracks involves forming a material having completely different properties, for example, a non-magnetic material such as aluminum from a magnetic recording material by some means. However, if it takes time and effort, even if one disk can be produced with insufficient performance, there is no specific method for mass production. At present, magnetic separation in a magneto-optical disk using DWDD is performed by scanning tracks adjacent to the right and left of a track used for information reproduction one by one with a laser beam having a stronger power than a recording laser beam required for information recording. Irradiation changes the state of the magnetic material (for example,
The magnetic separation is performed by changing the perpendicular magnetization film, which is the moving layer 2A, to an in-plane magnetization film or a discontinuous film). This was also unsuitable for mass production.
Therefore, an object of the present invention is to provide a magneto-optical disk using DWDD having high mass productivity.

[0009]

In order to solve the above-mentioned problems, the present invention provides a magneto-optical disk having the following constitutions (1) to (5).

(1) As shown in FIGS. 1 and 2, at least a recording layer 2 and a protective layer 3 are sequentially laminated on a transparent substrate 1 and information is recorded by using DWDD (Domain Wall Movement Detection System). Magneto-optical disks B and C for performing reproduction, wherein the transparent substrate 1 has a fine track pattern formed continuously in a spiral or concentric manner, and the recording layer 2 is formed on the transparent substrate 1. , At least a moving layer 2A, a switching layer 2B, and a memory layer 2C are sequentially laminated, and a track formed on the moving layer 2A is selectively connected to an adjacent track (in accordance with the track pattern). A magneto-optical disk characterized in that it is magnetically separated between.

(2) As shown in FIGS. 1 and 2, the magneto-optical disks B and C according to claim 1, wherein the moving layer 2
A magneto-optical disk characterized in that a magnetic separation portion 10 comprising a wedge-shaped groove (for example, a V-shaped groove) 4a or a projection (V-shaped projection) 4c exists between adjacent tracks formed on A. .

(3) As shown in FIG. 7, the magneto-optical disks B and C according to claim 1 or 2, wherein
The magneto-optical disk according to claim 1, wherein a width MM of the track A is smaller than a width AA of a recording track formed on the memory layer 2C.

(4) The magneto-optical disk according to claim 3, wherein the width MM of the reproduction track is about 90% or less of the width AA of the recording track.

(5) As shown in FIG. 8, the magneto-optical disk according to claim 4, wherein the reproduction track has a meandering MM.
1. A magneto-optical disk, wherein MM2 is about 10% or less of the width of a track formed on the transparent substrate 1.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magneto-optical disk according to the present invention will be described below in detail with reference to the drawings. FIGS. 1 and 2 are diagrams for explaining the configuration of the first and second embodiments of the magneto-optical disk of the present invention, and FIGS. 3, 4 and 5 are diagrams for explaining recording marks, respectively. 6 is a diagram for explaining a track, FIGS. 7 and 8 are diagrams for explaining a track on which a recording mark is recorded, and FIG. 9 is a diagram for recording when a reproduced track has meandering and when there is no meandering. FIG. 10 is a diagram showing a reproduced waveform of a recorded mark reproduced, FIG. 10 is a diagram for explaining a recorded mark enlarged at the time of reproduction, and FIG. 11 is a diagram for explaining a moving layer magnetically separated. The same components as those described above are denoted by the same reference numerals, and description thereof will be omitted.

The magneto-optical disks B and C of the present invention are shown in FIGS.
As shown in FIG. 2, a magneto-optical disk in which at least a recording layer 2 and a protective layer 3 are sequentially laminated on a transparent substrate 1 and records and reproduces information by using DWDD (Domain Wall Movement Detection Method). The transparent substrate 1 has a flat land (land track) 5 which is a fine track pattern, and a groove 4 (or a not-shown) which is a wedge-shaped (for example, V-shaped) groove having two slopes formed on both sides of the groove. (A flat groove or a groove track) is formed continuously and alternately in a spiral or concentric manner, and the recording layer 2 is formed on the transparent substrate 1 at least by the moving layer 2A, the switching layer 2B, and the memory layer. 2C are sequentially stacked, and tracks formed on the moving layer 2A are magnetically separated from adjacent tracks selectively in accordance with the track pattern. It is a disk.

More specifically, as shown in a magneto-optical disk B of FIG. 1, for example, a recording layer 2 comprising a moving layer 2A, a switching layer 2B, and a memory layer 2C, and a protective layer 3 on a plastic transparent substrate 1. Are sequentially laminated.
On the transparent substrate 1, a groove 4 for optical tracking, which is a fine track pattern, is continuously formed spirally or concentrically as a V-shaped groove. Flat lands 5 which are fine track patterns are continuously formed in a spiral or concentric manner between the grooves 4.

The magnetic separation in the magneto-optical disk B having such a configuration may be performed only on the moving layer 2A constituting the recording layer 2, and the groove 4 between the adjacent lands 5, 5 (or the land between the adjacent grooves 4, 4). What is necessary is to perform in 5). This magnetic separation is performed while the lands 5 remain as the perpendicular magnetization films formed by the sputter deposition on the transparent substrate 1, while the grooves 4 are in the non-perpendicular magnetization state (in-plane magnetization film or the state where the magnetic properties are lost (oxidation, nitridation). Etc.) or as a discontinuous film (burn-out)).
Of course, the magnetic separation in the magneto-optical disk B is caused by the movement layer 2
A, the switching layer 2B and the memory layer 2C may be penetrated.

In order to form the groove 4 in the above-mentioned non-perpendicular magnetization state or discontinuous film formation, as shown in FIG. The reflection and absorption effect of the irradiated magnetic separation light La is used. That is, the magnetic separation light La transmitted through the transparent substrate 1 is incident on one V-shaped wall surface 4aa of the V-shaped groove 4a, and repeats the incident and reflection between the opposite V-shaped wall surface 4aa. Eventually, it reaches the tip 4b of the V-shaped groove 4a. The light irradiation intensity per unit area that has reached the vicinity of the leading edge 4b is higher than that of the land 5 because the amount of light irradiation in this portion increases due to repeated reflection and reflection between one and the other V-shaped wall surface 4aa. Above the magnetic separation light L
The intensity is extremely higher than the light irradiation intensity when a is irradiated. As a result, heat generated by the magnetic separation light La is trapped in the vicinity of the front end 4b of the V-shaped groove 4a, resulting in an extremely high temperature state. Etc. occur. Also, V-shaped wall 4
Since aa has a smaller film thickness than the upper surface of the land 5 when the moving layer 2A is formed, it is easily damaged by such light irradiation. From this, the magnetic separation light L
This part can be easily changed to a non-perpendicular magnetization state (in-plane magnetization film, loss of magnetic characteristics (oxidation, nitridation, etc.), or discontinuous film formation (burn-out)) with a small amount of light irradiation a. It is. Thus, the magnetic separation in the magneto-optical disk B is performed in the moving layer 2A corresponding to each groove 4. In other words, a track formed on the moving layer 2A is magnetically separated from an adjacent track.

The above-mentioned magneto-optical disk B (shown in FIG. 1)
Is formed so that the V-shaped groove 4a is opened in the direction to open to the transparent substrate 1 side. In this case, irradiating the V-shaped groove 4a with the magnetic separation processing light La is necessary for forming the magneto-optical disk B. After forming all necessary films, the recording / reproducing surface is subjected to a batch light irradiation division method using a surface light source such as a xenon lamp, thereby selectively forming a non-magnetic film or a magnetic film only on the V-shaped groove 4a. Characteristic modification is performed.

On the other hand, in contrast to the case where the V-shaped groove 4a of the magneto-optical disk B is formed so as to open toward the transparent substrate 1,
As shown in FIG. 2, the V-shaped protrusion 4c of the magneto-optical disk C
Are formed in a direction to open to the opposite side (the protective layer 3 side) of the transparent substrate 1. The configuration of the magneto-optical disk C is similar to that of the above-described magneto-optical disk B in which the opening direction of the V-shaped groove 4a is reversed, and the other configuration is the same. In the magneto-optical disk C shown in FIG.
The same reference numerals are given to the same components as those of the magneto-optical disk B shown in FIG.

In the magnetic separation of the magneto-optical disk C, the V-shaped projection 4c is formed in a direction to open to the protective layer 3 side, so that the V-shaped projection 4c is irradiated with the magnetic separation light La. After the formation of the moving layer 2A on the transparent substrate 1, this is performed from the protective layer 3 side by a batch light irradiation division method using a surface light source such as a xenon lamp. Also in this case, as described above, this portion can be easily changed to a non-perpendicular magnetization state (in-plane magnetization film or a state in which the magnetic properties are lost (oxidation, nitridation, etc.) or a slight irradiation of the magnetic separation processing light La, or
It is possible to form a discontinuous film (burn-out). Needless to say, the switching layer 2B, the memory layer 2C, and the protective layer 3 are sequentially stacked on the magnetically separated moving layer 2A.

Usually, after a phase-change recording medium is formed in an amorphous state, the phase-change recording medium is initialized with a laser beam in order to change the phase into a crystalline state. The intensity of the laser beam is several times the energy density required for recording and reproduction. The degree is sufficient and the intended purpose can be achieved. Crystallization can also be performed by irradiation with a surface light source other than laser light having the same energy density. However, the latter case is not usually adopted because the rewriting characteristics are delicate due to the wavelength dependency and others, and the desired characteristics cannot be obtained. In the case of the present invention, there is no such a subtle problem, and the process is merely a process of changing the non-perpendicular magnetization film or changing the magnetic characteristics. Therefore, as shown in FIG. (Angle of the land 5 with respect to the recording / reproducing surface) θ, and the irradiation energy based on the thermal conductivity / reflectivity / absorbance of the films (the moving layer 2A, the switching layer 2B, and the memory layer 2C) constituting the recording layer 2. If it is determined, the V-shaped effect is assisted, and the angle θ of the V-shaped groove 4a and the V-shaped projection 4c shown in FIGS.
0.2 Watt · sec / c in the case of about 0 to 85 degrees
Irradiation of a surface light source of a xenon lamp of about m <2> can sufficiently selectively or non-perpendicularly magnetize (magnetic separation) a part or the whole of the V-shaped groove 4a and the V-shaped protrusion 4c of the moving layer 2A. It is known. As a matter of course, the irradiation light energy density on the recording / reproducing surface varies depending on the recording marks existing on the lands 5 other than the V-shaped grooves 4a and the V-shaped protrusions 4c of the magneto-optical disks B and C (for example, non-perpendicular magnetization film formation). The density should not be higher than that which does not return to the original state at normal temperature. Also,
The light source used in the present process is desirably of a wavelength as short as possible (ultraviolet light or the like) so that the light reaches deep inside the V-shaped groove 4a.

The recording marks recorded on the recording layer 2 of the magneto-optical disk A using the DWDD shown in FIGS. 1 and 2 usually employ a magnetic field modulation recording method. It is known that the short mark M1 has a crescent shape and the long mark M2 has an arrow shape as shown in FIGS. A recording mark reproducing method for reproducing a recording mark recorded on the recording layer 2 by DWDD is based on the crescent-shaped or arrow-shaped marks M1 and M2.
From the laser beam L for reproduction at the same time
Enlarging (super-resolution) reproduction of a transfer recording mark in the moving layer 2A caused by the thermal gradient of the moving layer 2A generated by (reading light), thereby improving the C / N of the reproduction detection signal. It is.

In the magneto-optical disks B and C using DWDD, the perpendicular magnetic domain wall of the transferred recording mark is set to facilitate the enlargement of the fine recording mark transferred from the memory layer 2C to the moving layer 2A. Use a technique that does not exist on the entire circumference of the mark. That is, as shown by thick lines in FIGS. 4A and 4B, perpendicular magnetic domain walls are formed only at the front end f and the rear end e of the recording marks M11 and M21 in the tangential direction (enlargement direction; scanning direction 1A of the laser beam L). (Domain wall 2Aa shown in FIG. 13)
To exist. In this way, it has been found that the expansion of the perpendicular magnetization domain of the moving layer 2A easily occurs with a slight thermal gradient. In the state where the perpendicular magnetization domain wall 2Aa is present in the entire circumferences f, g, h, e of the recording marks M11, M21, very large energy such as recording laser light for moving the domain wall in the enlargement direction is required. Domain wall movement 2Ab is not easy.

As will be readily understood from actual recording, it is difficult to find the ideal recording marks M1 and M2 as shown in FIGS. 3A and 3B. M
1 and M2, the recording becomes vague or not transferred, and the recording marks M1 shown in FIGS.
2, M22, a recording mark in which details of g and h are blurred is observed. As a result, it should be particularly noted that the width of the crescent-shaped mark M12 in the radial direction is the arrow-shaped mark M2.
2 is often shorter than the radial width.
The extremely thin portion of the crescent-shaped mark MM12 has a crescent shape corresponding to the projected shape of the recording spot light because the energy distribution on the magneto-optical disks B and C formed by the substantially circular outer shape of the recording spot light fluctuates slightly. Becomes ambiguous when the outline is formed. That is, one cause is energy shortage, and magnetization reversal recording does not occur in the dotted line portions g and h of the recording mark M12 in FIG. 5A corresponding to the dotted line portions g and h in FIG. 4A. It is considered that an ambiguous shape is generated. Strictly speaking, the arrow mark-shaped recording mark M22 corresponding to the long wavelength also corresponds to FIG.
It becomes like.

Overlooking such a phenomenon, when designing the magneto-optical disks B and C, the radial widths of the recording marks M1 and M2 on the recording tracks formed on the memory layer 2C and the transfer of the moving layer 2A. If the width of the recording area (playback track) is set, the width of the former is smaller than the width of the latter unexpectedly, and as a result, reproduction by DWDD fails as described above. Since it is important that the DWDD does not form the perpendicular magnetic domain walls g, h in the radial position direction of the recording transfer marks M1, M2 as described above, the moving layer 2
In A, the magnetic separation is performed in a track shape by any method.

FIG. 6 shows a moving layer 2 magnetically divided into tracks.
3 shows the magnetization state of A. That is, the width of the transfer recording area (track width) of the moving layer 2A is larger than the width of the recording marks M1 and M2.
6 is set to be small, and as shown in FIG. 6, for example, the magnetic separation portion 10 between the lands 5 which are recording tracks is in a state where magnetism is completely lost, for example, a completely non-magnetic material such as aluminum is disposed. Although there is a method of changing the magnetic field, it is very difficult to do so. Therefore, usually, the degree of change in the magnetism of a desired portion of the moving layer 2A (for example, by reducing the perpendicular magnetic anisotropy, To the extent that a track that is not a perpendicular magnetization film is formed) to perform magnetic separation. DWDD produced in this way
FIG. 7 shows a state in which information (recording marks M12, M22) recorded on the memory layer 2C of the magneto-optical disk using the above method is transferred and recorded on the moving layer 2A.

As shown in FIG. 7, the short mark M12 in the shape of a crescent moon to the long mark M22 in the shape of an arrow feather have portions M12a and M22a hanging on the magnetic separation portion 10. A state where the portions M12a and M22a of the marks M12 and 22 are hardly applied to the magnetic separation portion 10, that is, the memory layer 2
The width AA of the recording marks M12 and M22 recorded in C in the radial direction is the width (track width) of the transfer recording area of the moving layer 2A.
At the same level as or slightly longer than the MM, the marks M12, M3, M2, M3, M2, M3, M2, M3, M2 due to fluctuations in the applied magnetic field intensity due to the tracking servo state during recording, the focus state of the recording laser beam, the positional accuracy of the recording magnetic head, etc. The overlap of the M22 with the magnetic separation part 10 may be missing. In view of this, the present invention takes this into consideration, and as shown in FIG. 7, the moving layer 2A with respect to the width AA of the recording marks M12 and M22 (that is, the width of the recording recording track formed on the memory layer 2C).
Of the reproduction track width MM of about 90% or less (about 90%).
Percent). This numerical value is evaluated as a value (approximately twice) that matches the standard value of the tracking error tolerance when reproducing the normal magneto-optical disks B and C.

However, it has been found that the jitter of the reproduced signal may not always be reduced only under the condition that the reproduced track width MM is constant within the above specification. For example,
As shown in FIG. 8B, the reproduction track 5 of the moving layer 2A
This is the case where A is meandering. Both edges 5a and 5b of the track 5A meander. However, the recording track 5B formed on the memory layer 2C (shown in FIG. 8A)
Are reproduced tracks 5A formed on the moving layer 2A (FIG. 8).
(Illustrated in (B)) and meandering in pairs
The recording mark M12 is recorded on the recording track 5B, and the reproduction laser beam L that plays a role of enlarging and reproducing the recording mark M12 magnetically transferred to the reproduction track 5A of the moving layer 2A by moving the magnetic domain wall is ideal. If the tracking control is accurately performed on the reproduction track 5A, the jitter is usually very small except for the case where the magnetic separation of the moving layer 2A is performed in the post-process of forming the recording film on the disk. Also, it is known that the jitter is very small if the meandering MM1 and MM2 of the reproduction track are about 10% or less of the width of the track formed on the transparent substrate 1.

It is actually extremely difficult to satisfy such conditions in a DWDD magneto-optical system. In practice, the recording track 5B and the reproduction track 5A are generally processed in different steps. If the specifications have a correlation as shown in FIG. 8, the reproduced signal will have a jitter as shown in FIG. 9 regardless of where the slice levels a ″ and b ″ of the reproduced signal are set. Become. In the figure, a broken line indicates a reproduction waveform when the reproduction track 5A has no meandering, and a solid line indicates a reproduction waveform when the reproduction track 5A has the meandering. That is, a waveform obtained by reproducing the recording mark M12 can obtain a substantially constant reproduction level when the reproduction track 5A does not meander. On the other hand, if the reproduction track 5A has meandering, a constant reproduction level cannot be obtained. In this case, jitter occurs. In particular, it is desirable that this meandering be strictly controlled at a cycle of about the mark length of all signal systems employed in the system.

As shown in FIG. 10, the recording mark M12 magnetically transferred to the reproduction track 5A (shown in FIG. 8B).
The cross hatch portion M12A in which is enlarged is read by the reproduction spot light s. For example, in a 3T reproduction signal a and a 3T reproduction signal b (corresponding to the recording marks M12a and M12b shown in FIG. 8B) in a certain signal system, DWDD
Although the areas M12aA and M12bA related to the above should have the same area, they have different areas because both edges 5a and 5b of the track 5A meander. As a result, FIG.
As shown in (1), an amplitude difference (a ''-b '') of the reproduced signal is generated, which leads to jitter generation. Strictly speaking, even if the areas M12aA and M12bA of the reproduction marks related to DWDD have the same area, if there is fluctuation in the tracking of the reproduction laser beam, the amplitude difference (a ''-b It is apparent from the principle of reproducing information on an optical disk or a magneto-optical disk that an amplitude difference similar to that of ″) occurs. Just because there is no difference in the area of the reproduction mark (enlarged magnetic domain) does not mean that there is no difference in the amplitude of the reproduction signal, that is, there is no jitter in the reproduction signal. This jitter reduction is expected to be solved by another technology.

As a method of magnetic division, for example, only a portion of the moving layer 2A which is to be magnetically divided is burned out by irradiating light larger than the density of laser light, or the magnetic characteristics are changed (for example, the recording track 5B). Is changed to an in-plane magnetized film in contrast to the perpendicular magnetization) or the grooved substrate 1
(E.g., as shown in FIG. 11, there is a portion where the magnetic film 2AA is not attached to the separation layer, as shown in FIG. 11). The method may be performed to set a moving layer having a form satisfying the present invention.

[0034]

As described above, in the magneto-optical disk of the present invention, at least a recording layer and a protective layer are sequentially laminated on a transparent substrate, and information is recorded / reproduced using DWDD (Domain Wall Movement Detection System). In the magneto-optical disk to be performed, the transparent substrate is formed by continuously forming a fine track pattern spirally or concentrically, and the recording layer is formed on the transparent substrate, at least a moving layer, a switching layer Since the memory layer is sequentially stacked and the track formed on the moving layer is magnetically separated from the adjacent track, the light reflection and absorption effect in the wedge-shaped track adjacent portion is used, for example. Thus, only the desired portion of the moving layer is selectively and magnetically separated, and the D and D obtained by performing the magnetic separation with the width and depth as required.
A WDD-compliant magneto-optical disk can be provided.
The width of the reproduction track in the moving layer is smaller than the width of the recording track formed in the memory layer, for example, about 9
Since it is set to 0% or less, the margin of the entire system when performing DWDD recording / reproduction is improved, and the enlarged reproduction of the magnetic transfer recording mark by moving the domain wall can be practically and reliably performed. Furthermore, by setting the meandering amount of the reproduction track to be about 10% or less of the width of the track formed on the transparent substrate, the reproduction signal of the reproduction signal at the time of edge recording / reproduction (mark length recording / reproduction) at both edges of the reproduction track. Jitter can be reduced. Needless to say, the jitter during reproduction can be reduced also in the case of the position recording / reproduction system. Further, there is an effect that a magneto-optical disk having such an effect can be produced with good mass productivity.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration of a first embodiment of a magneto-optical disk according to the present invention.

FIG. 2 is a diagram for explaining a configuration of a second embodiment of the magneto-optical disk according to the present invention.

FIG. 3 is a diagram for explaining recording marks.

FIG. 4 is a diagram for explaining recording marks.

FIG. 5 is a diagram for explaining recording marks.

FIG. 6 is a diagram for explaining a track.

FIG. 7 is a diagram for explaining a track on which a recording mark is recorded.

FIG. 8 is a diagram for explaining a track on which a recording mark is recorded.

FIG. 9 is a diagram showing a reproduction waveform obtained by reproducing a recorded mark when a reproduction track has meandering and when there is no meandering.

FIG. 10 is a diagram for explaining a recording mark enlarged during reproduction.

FIG. 11 is a view for explaining a magnetically separated moving layer.

FIG. 12 is a diagram illustrating a cross-sectional structure of a magneto-optical disk using DWDD.

FIG. 13 is a diagram for explaining DWDD.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Recording layer 2A Moving layer 2B Switching layer 2C Memory layer 3 Protective layer 4 Land 4a V-shaped groove 4c V-shaped protrusion 5 Groove 10 Magnetic separation part A, B, C Magneto-optical disk AA Recording track width, M1, MM2 Both edges M12, M22 Recording mark MM Playback track width

Claims (5)

[Claims] 1. A method according to claim 1, wherein at least a recording layer and a protective layer are sequentially laminated on a transparent substrate, and a DWDD (domain wall motion detection method).
A magneto-optical disk for recording and reproducing information by using the transparent substrate, wherein a fine track pattern is continuously formed in a spiral or concentric shape, and the recording layer is formed on the transparent substrate. A magneto-optical disk, comprising: at least a moving layer, a switching layer, and a memory layer sequentially laminated, and wherein a track formed on the moving layer is magnetically separated from an adjacent track. 2. The magneto-optical disk according to claim 1, wherein a magnetic separation portion comprising a wedge-shaped groove or projection exists between adjacent tracks formed on the moving layer. Magneto-optical disk. 3. The magneto-optical disk according to claim 1, wherein a width of a reproduction track of the moving layer is smaller than a width of a recording track formed on the memory layer. Magneto-optical disk. 4. The magneto-optical disk according to claim 3, wherein the width of the reproduction track is about 9 times the width of the recording track.
A magneto-optical disk characterized by being at most 0%. 5. The magneto-optical disk according to claim 4, wherein a meandering amount of the reproduction track is about 10% or less of a width of a track formed on the transparent substrate. .