Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
  • G11B11/10586—Record carriers characterised by the selection of the material or by the structure or form characterised by the selection of the material
  • G11B11/10589—Details
  • G11B11/10591—Details for improving write-in properties, e.g. Curie-point temperature
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B11/00—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor
  • G11B11/10—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field
  • G11B11/105—Recording on or reproducing from the same record carrier wherein for these two operations the methods are covered by different main groups of groups G11B3/00 - G11B7/00 or by different subgroups of group G11B9/00; Record carriers therefor using recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier, e.g. light induced spin magnetisation; Demagnetisation by thermal or stress means in the presence or not of an orienting magnetic field using a beam of light or a magnetic field for recording by change of magnetisation and a beam of light for reproducing, i.e. magneto-optical, e.g. light-induced thermomagnetic recording, spin magnetisation recording, Kerr or Faraday effect reproducing
  • G11B11/10582—Record carriers characterised by the selection of the material or by the structure or form
  • G11B11/10584—Record carriers characterised by the selection of the material or by the structure or form characterised by the form, e.g. comprising mechanical protection elements

Definitions

• the present invention relates to a magneto-optical recording medium capable of overwriting information by a light intensity modulation method.
• FIG. 8 is a cross-sectional view schematically showing the film structure of this type of magneto-optical recording medium, wherein 21 is a magneto-optical recording medium, 22 is a substrate, 23 is a recording layer, and 24 is an auxiliary layer. The layers are shown. As shown in the coercive force-temperature characteristic diagram of FIG.
• the recording layer 23 has a higher coercive force at room temperature than the auxiliary layer 24 and has a lower cure than the auxiliary layer 24. It is formed of a perpendicular magnetization film having points.
• the auxiliary layer 24 has a lower coercive force at room temperature than the recording layer 23 and a higher perpendicular magnetic film than the recording layer 23, and has a higher Curie point than the recording layer 23. Formed.
• the overwriting mechanism of this type of magneto-optical recording medium will be described below by taking a so-called parallel-type magneto-optical recording medium as an example.
• Fig. 10 is an explanatory diagram of a drive that overwrites the light intensity modulation method.
• a laser that can be intensity-modulated to three values: read level, erase (L) level, and record (H) level 25, a magnet 26 for applying a bias magnetic field during recording, and an initialization magnet 27 for overwriting
• the L-level laser is set to a value that can heat the recording layer 23 to the Curie temperature
• the H-level laser is set to a value that can heat the Auxiliary layer 24 to the Curie temperature.
• the bias magnetic field applying magnet 26 is formed of a magnet that generates a magnetic field weaker than the initializing magnet 27, and is disposed to face the laser 25, and is unidirectionally arranged on the magneto-optical recording medium 21. For example, an upward magnetic field is applied.
• the initialization magnet 27 is a magnet that generates a stronger magnetic field than the bias magnetic field applying magnet 26, and the magnetic field of the magneto-optical recording medium 21 is higher than the set position of the bias magnetic field applying magnet 26. It is arranged on the upstream side in the rotation direction and applies a downward magnetic field to the magneto-optical recording medium 21.
• the magnetization of the recording layer 23 and the magnetization of the auxiliary layer 24 are both upward.
• the magnetization of the recording layer 23 and the magnetization of the auxiliary layer 24 are both directed downward as shown in FIG. 11 (b).
• the initialization magnet 27 is reset.
• the magnetization of the auxiliary layer 24 is aligned downward by the downward magnetic field. That is, in the recording section, the state shown in FIG. 11A is changed from the state shown in FIG. 11A to the state shown in FIG. 11C, and in the erasing section, the state shown in FIG. 11B remains unchanged.
• the state (c) in FIG. 11 the partial magnetization of each of the layers 23 and 24 is in the opposite direction, so that an interface domain wall 27 is generated.
• this type of magneto-optical recording medium performs overwriting by utilizing the exchange coupling force acting between the recording layer 23 and the auxiliary layer 24. It is preferable that the exchange coupling force is large. On the other hand, a magneto-optical recording medium having a large exchange coupling force requires a large initialization magnet to initialize the auxiliary layer 24,
• the disadvantages are that (i) the device becomes large, (ii) the dynamic characteristics of the head deteriorate, and (iii) the interface magnetic wall is not stabilized in the absence of an external magnetic field and the recording magnetic domains are easily lost. Therefore, in this type of magneto-optical recording medium, the exchange coupling force acting between the recording layer 23 and the auxiliary layer 24 does not impair the recording and erasing characteristics, and (i) ⁇ (Iii) It is necessary to adjust the value to such a degree that no disadvantage is caused.
• a recording layer 23 and an auxiliary layer 24 (generally, an amorphous alloy of a rare earth element and a transition metal is used) are directly laminated as in a conventional magneto-optical recording medium. As a result, the exchange coupling force becomes much larger than expected, and an initialization magnet of at least about 5 to 6 [K 0 e] is required. Also, in proportion to that, the recorded magnetic domains are easily lost.
• An object of the present invention is to provide a magneto-optical recording medium capable of reducing the size of an initialization magnet and realizing stable recording.
• a magneto-optical recording layer an intermediate layer made of a magnetic thin film having an optical reflectance of 50% or more, and a coercive force at room temperature as compared with the recording layer.
• a magneto-optical recording medium characterized in that auxiliary layers each having a lower curability, a higher Curie point than that of the recording layer, and having perpendicular magnetizability are sequentially stacked.
• a magneto-optical recording comprising: a recording layer for performing thermomagnetic recording and magneto-optical reading; and a trapping layer for enabling overwriting of information by an exchange coupling force between the recording layer and the recording layer.
• an intermediate layer is provided between the recording layer and the auxiliary layer to reduce the exchange coupling force acting between the two layers.
• the intermediate layer includes an exchange coupling between the recording layer and the auxiliary layer.
• a magnetic thin film with an easy axis of magnetization in a direction other than the direction perpendicular to the film surface or a magnetic thin film without an easy axis of magnetization can be As the magnetic thin film having an easy axis of magnetization in a direction other than the perpendicular direction, a magnetic thin film having an easy axis of magnetization aligned in the film surface direction is particularly preferable.
• an alloy thin film containing a noble metal and a transition metal as main components for example, rhodium, phosphorus, and the like.
• At least one type of alloy thin film mainly composed of a transition metal element can be mentioned.
• Radium cobalt alloy or platinum-cobalt alloy is particularly suitable.
• the thickness of the intermediate layer is particularly important. If the thickness of the intermediate layer is 500 A or more, the recording and erasing of information will be adversely affected. Therefore, it is preferable that the number be 500 or less.
• the size of the initialization magnet for initializing the auxiliary layer can be reduced, and The size of the head can be reduced and the dynamic characteristics of the head can be improved.
• the interface domain wall can be stabilized, so that the recording magnetic domain does not easily disappear.
• FIG. 1 is a cross-sectional view showing a film structure of a medium according to the first embodiment
• FIG. 2 is a cross-sectional view showing a bonding structure of the medium according to the first embodiment
• FIG. 3 is a medium according to the second embodiment
• FIG. 4 is a cross-sectional view showing the laminated structure of the medium according to the second embodiment
• FIG. 5 is a graph showing the coercive force-temperature characteristics and the saturation magnetization-temperature characteristics of the recording layer and the auxiliary layer.
• Figure 6 shows the magnitude of the laser power required for information overwriting
• Figure 7 shows the magnitude of the initialization magnetic field required for information overwriting.
• FIG. 8 is a cross-sectional view showing the film structure of a magneto-optical recording medium according to the prior art
• FIG. 9 is a coercive force-temperature characteristic diagram of the magneto-optical recording medium according to the prior art
• FIG. 4 is an explanatory diagram for explaining the principle of overwriting.
• the ultraviolet curable resin layer 2 on which a pre-format pattern (not shown) is transferred is adhered to one surface of the glass disk 3 by a so-called 2P method.
• a transparent substrate 4 with a pre-format pattern was produced.
• a silicon nitride enhancing layer 5 having a thickness of about 850 A and a thickness of about 4 0 OA terbium-iron-cobalt amorphous alloy recording layer 6 0 OA of a platinum-cobalt alloy intermediate layer 7, about 150 OA of a terbium-dispersium-iron-cobalt amorphous alloy auxiliary layer 8, and
• the silicon nitride protective layer 9 of about 100 A was sequentially laminated to produce a single disk 10 shown in FIG.
• FIG. A magnetic disk 11 was fabricated.
• reference numeral 12 indicates an inner peripheral spacer
• 13 indicates an outer peripheral spacer
• 14 indicates an air gap formed between the disk single plates 10.
• a transparent polycarbonate substrate 15 having a pre-formed pattern formed on one side was produced by an injection molding method.
• the silicon nitride-based enhancement layer 5 having a thickness of about 850 Approximately 30 OA of terbium mono-cobalt amorphous alloy recording layer 6, approximately 5 OA of palladium-cobalt alloy intermediate layer 7, and approximately 120 OA of film thickness An auxiliary layer 8 made of gadolinium-terbium-iron-cobalt amorphous alloy and a protective layer 9 made of silicon nitride having a thickness of about 1000 A are sequentially laminated, as shown in FIG. A disk single plate 16 was produced.
• reference numeral 18 denotes an adhesive layer for bonding the individual disk single plates 16.
• a transparent substrate 15 made of polycarbonate having a pre-formatted pattern formed on one surface was produced by an injection molding method.
• a silicon nitride enhancement layer 5 having a thickness of about 850 persons and a film were formed.
• a recording layer 6 made of terbium-iron-cobalt amorphous alloy having a thickness of about 40 OA, an intermediate layer 7 made of a palladium-nickel alloy having a thickness of about 150 A, and a film thickness of about 150 A 100 OA terbium-doped spray iron-cobalt amorphous alloy auxiliary layer 8, silicon nitride protective layer 8 with a thickness of about 200 A, and aluminum nitride protective layer 8 with a thickness of about 500 A
• a heat dissipating layer 9 made of an amorphous titanium alloy was sequentially laminated to produce a single disk 16 similar to that shown in FIG.
• Fig. 5 shows the coercive force vs. temperature characteristics and saturation magnetization vs. temperature characteristics of the recording layer and auxiliary layer formed on each of the magneto-optical disks of the first to third examples. Characteristics I knew he was wearing it. That is, the recording layer 6 has a higher coercive force at room temperature than the auxiliary layer 8, and has one point lower than the auxiliary layer 8. The recording layer 6 has a lower saturation magnetization at room temperature than the auxiliary layer 8.
• the L-level laser power required for erasing the recording magnetic domain and the H-level laser power required for recording information were examined. As shown in Fig. 6, the previously recorded magnetic domains can be erased by applying an L-level laser power of about 4 mW or more. It was found that information could be recorded by applying an H level laser power of about 14 mW or more.
• the signal of [MHz] has been completely erased, and the signal of 1.85 [MHz] recorded later has reached the saturation level, and an initialization magnetic field of 5 to 6 [K0e] is applied. It has been found that the initialization magnet can be made much smaller than the conventional technology.
• the signal of 1.85 [MHz] is overwritten by intensity-modulating the L level to 6 [mW] and the H level to 14 CmW).
• the signal of 1.85 [MHz] was modulated to an L level of 5.5 [mW] and an H level of 12 [mW], and over modulated.
• the signal of [MHz] was intensity-modulated to an L level of 6 [mW] and an H level of 12 [mW] and overwritten.
• the power of the reproducing laser beam was 1.5 Cm W).
• magneto-optical disks of the first to third embodiments confirmed the same effects as described above.
• the intermediate layer for reducing the exchange coupling force acting between the recording layer and the auxiliary layer is provided between the recording layer and the auxiliary layer, so that the initial state for initializing the auxiliary layer is provided.
• the fossil magnet can be downsized, and the device can be downsized and the dynamic characteristics of the head can be improved.
• the interface domain wall can be stabilized, so that the recording magnetic domain does not easily disappear and stable recording characteristics can be obtained.

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Citations (6)

• 1990
  • 1990-10-17 JP JP27653290A patent/JPH04153932A/ja active Pending
• 1991
  • 1991-10-16 WO PCT/JP1991/001407 patent/WO1992007358A1/ja active Application Filing
  • 1991-10-16 DE DE19914192566 patent/DE4192566T1/de not_active Withdrawn

Patent Citations (6)

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