JP2006190417A - Magneto-optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magneto-optical recording medium suitable for attaining high recording density and also realizing satisfactory recording magnetic field sensitivity. <P>SOLUTION: This magneto-optical recording medium X1 has a laminated structure, which is composed of a recording layer 11 having a laminated structure composed of a plurarity of perpendicular magnetized films 11a, 11b, and a nucleating layer 24 having a fine rugged surface 24a on the recording layer 11 side. The respective perpendicular magnetized films of the recording layer 11, are provided with denser structure as nearer to the nucleating layer 24, preferably the perpendicular magnetized film is formed under the lower gas pressure condition as nearer to the nucleating layer 24, and the thickness of the perpendicular magnetized film is thinner as nearer to the nucleating layer 24. It is preferable that the recording layer 11 contains nitrogen. The respective perpendicular magnetized films of the recording layer 11 are provided with higher nitrogen composition ratio as nearer to the nucleating layer 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magneto-optical recording medium having a recording layer composed of a perpendicular magnetization film.

  A magneto-optical recording medium is known as one form of optical media from which information is optically read. A magneto-optical recording medium is a rewritable medium that is thermomagnetically recorded and reproduced using the magneto-optical effect. The magneto-optical recording medium is described in, for example, the following Patent Documents 1 to 3.

Japanese Patent Application Laid-Open No. 6-290496 JP 2001-56777 A JP 2003-132599 A

  FIG. 7 shows a magneto-optical disk X4 which is an example of a conventional magneto-optical recording medium. The magneto-optical disk X4 has a laminated structure including a substrate S, a recording magnetic part 71, a pregroove layer 72, a heat conductive layer 73, dielectric layers 74 and 75, and a protective film 76, and a front illumination. It is configured as a magneto-optical disk of the type.

  The recording magnetic unit 71 has a magnetic structure capable of performing two functions of thermomagnetic recording and reproduction utilizing the magneto-optical effect, and is composed of one or more magnetic films according to the reproduction method ( Including a recording layer in contact with the dielectric layer 74). The magnetic film is a rare earth-transition metal amorphous alloy perpendicular magnetization film. The pregroove layer 72 is made of a resin material, and an uneven shape (not shown) such as a pregroove is formed on the surface of the recording magnetic portion 71 side. The heat conductive layer 73 is a part for efficiently transmitting heat generated in the recording magnetic part 71 and the like to the substrate S side during laser irradiation, and is made of a high heat conductive material. The dielectric layers 74 and 75 are parts for avoiding an inappropriate magnetic influence from the outside on the recording magnetic part 71. The protective film 76 is a part for protecting the recording magnetic part 71 from dust, and is made of a light transmissive resin material.

  In manufacturing the magneto-optical disk X4 having such a configuration, first, the pregroove layer 72 is formed on the substrate S by, for example, a so-called 2P method. Next, the heat conductive layer 73, the dielectric layer 74, the recording magnetic part 71 (including the recording layer in contact with the dielectric layer 74), and the dielectric layer 75 are sequentially formed on the pre-groove layer 72 by sputtering, for example. Is done. Thereafter, a protective film 76 is formed on the dielectric layer 75 by, eg, spin coating.

  When recording information on the magneto-optical disk X4, for example, with the disk rotated, a recording laser (not shown) is continuously pulsed from the protective film 76 side to the recording magnetic unit 71. As a recording magnetic part 71 is heated locally and sequentially, a recording magnetic field modulated in a predetermined manner is applied to the temperature rising portion by a magnetic recording head (not shown). Thereby, in the recording magnetic part 71 or the recording layer included therein, a plurality of magnetic domains (record marks) whose magnetization directions are sequentially reversed are formed continuously in the circumferential direction of the magneto-optical disk X4 or in the track extending direction. In this way, predetermined information or signals are recorded as changes in the magnetization direction in the recording magnetic part 71 or the recording layer included therein.

  In the magneto-optical disk X4, the smaller the minimum recording mark (magnetic domain) that can be stably formed in the recording layer by information recording as described above, the higher the recording resolution and the higher the recording density. As the amount of information processing in a computer system increases, a higher recording density is required for recording media such as magneto-optical disks.

  On the other hand, in the technical field of magnetic materials, it is known that the degree of the fineness of stable magnetic domains that can be formed in an amorphous magnetic film is affected by the fine unevenness of the underlying surface on which the magnetic film is laminated. Yes. Specifically, it is known that there is a tendency that a smaller stable magnetic domain can be formed in the amorphous magnetic film formed on the underlying surface as the unevenness having an appropriate roughness is present and the unevenness is finer. It has been. The domain wall coercive force of the amorphous magnetic film increases due to the unevenness of the lower ground, the fluctuation of the position of the domain wall existing in the film (domain wall movement) is suppressed, and the domain is stabilized (pinning action). The magnetic domain structure of the amorphous magnetic film is miniaturized.

  Therefore, in the magneto-optical disk X4, a nucleation layer 77 may be provided as shown in FIG. 8 for the purpose of miniaturizing the minimum recording mark (magnetic domain) that can be stably formed in the recording layer. The nucleation layer 77 is formed on the dielectric layer 74 by, for example, sputtering as a base film for forming the recording magnetic part 71 or recording layer, and on the recording layer side, the recording magnetic part 71 or recording layer is formed. It has a fine uneven surface 77a with a fine uneven shape for exerting a pinning action on the layer.

  For example, in the case where the nucleation layer 77 is employed as shown in FIG. 8 in the magneto-optical disk X4, the recording layer at the temperature rise during the information recording as described above (below the Curie temperature of the recording layer), compared to the case where the nucleation layer 77 is not employed. The domain wall coercive force is large. Therefore, when the nucleation layer 77 is employed as shown in FIG. 8 in the magneto-optical disk X4, the intensity of the recording magnetic field required to form the recording mark (magnetic domain) in the recording layer is larger than when the nucleation layer 77 is not employed. (This is because the recording magnetic field is required to have a strength capable of forming a magnetic domain against the domain wall coercive force). That is, so-called recording magnetic field sensitivity decreases. As the recording mark to be formed is shorter, the required strength of the recording magnetic field tends to increase (that is, the recording magnetic field sensitivity decreases).

  If the nucleation layer 77 is employed in the magneto-optical disk X4 as shown in FIG. 8, the required strength of the recording magnetic field may be excessively increased. Since there is a restriction on the strength of the magnetic field that can be generated by the magnetic recording head during information recording, if the required strength of the recording magnetic field is excessively large, information cannot be properly recorded. In this case, it is impossible to effectively increase the recording density by employing the nucleation layer.

  As described above, in the conventional magneto-optical disk X4 using the nucleation layer 77, the recording magnetic field sensitivity is too low, and it may not be possible to effectively increase the recording density by employing the nucleation layer.

  The present invention has been conceived under the circumstances as described above, and provides a magneto-optical recording medium suitable for achieving a high recording density and realizing a good recording magnetic field sensitivity. Objective.

  According to a first aspect of the present invention, a magneto-optical recording medium is provided. This magneto-optical recording medium has a laminated structure comprising a recording layer having a laminated structure composed of a plurality of perpendicular magnetization films, and a nucleation layer having a fine irregular surface on the recording layer side. Each perpendicular magnetization film of the recording layer has a denser film structure as the perpendicular magnetization film is closer to the nucleation layer.

  In the technical field of magnetic materials, it is known that the degree of the fineness of stable magnetic domains that can be formed in an amorphous magnetic film is affected by the film structure constituting the magnetic film. Microscopically, there may be holes and voids in the amorphous magnetic film, but these voids and voids suppress the fluctuation of the position of the magnetic domain wall magnetically formed in the magnetic film, thereby creating a magnetic domain. Has a pinning action to stabilize. Since the amorphous magnetic film has a rough film structure, the larger the pores and voids existing in the magnetic film, the stronger the pinning action in the magnetic film tends to form a smaller stable magnetic domain. In the recording layer of the magneto-optical recording medium of the first aspect, the perpendicular magnetization film closer to the nucleation layer has a dense film structure and tends to have fewer or fewer vacancies and voids. The perpendicular magnetization film closer to the layer has a weaker pinning effect derived from the film structure.

  On the other hand, the recording layer of the magneto-optical recording medium also has a pinning action derived from the shape of the fine uneven surface (fine uneven shape) of the nucleation layer located immediately below. This pinning effect occurs over the entire thickness of the recording layer, but the closer the portion of the recording layer is to the nucleation layer (fine irregular surface), the stronger the pinning effect.

  In the recording layer of the magneto-optical recording medium, the perpendicular magnetization film closer to the nucleation layer has a finer film structure (and therefore the pinning effect derived from the film structure is weaker), and the perpendicular magnetization film is farther from the nucleation layer. As shown, the membrane structure is set to be rough (therefore, the pinning action derived from the membrane tissue is strong). With such a configuration, the pinning effect derived from the film structure and the nucleation layer can be obtained at a site near the nucleation layer (fine irregular surface) in the recording layer while obtaining a sufficient pinning effect throughout the thickness of the recording layer. It is suitable for avoiding excessive superimposition with the derived pinning effect. By obtaining a sufficient pinning effect over the entire thickness of the recording layer, while avoiding excessive superposition of the pinning action derived from the film structure and the pinning action derived from the nucleation layer, the recording layer ( In the perpendicular magnetization film), it is possible to avoid the domain wall coercive force from becoming excessive, and to obtain a domain wall coercive force having sufficient strength but not excessive. By realizing a sufficient strength for the domain wall coercive force, it is possible to stabilize the minute magnetic domains in the recording layer and increase the recording density. On the other hand, by realizing a strength that is not excessive with respect to the domain wall coercive force, it is possible to obtain a good recording magnetic field sensitivity by suppressing the strength of the recording magnetic field to be applied in order to form the stable minute magnetic domain. As described above, the magneto-optical recording medium according to the first aspect of the present invention is suitable for increasing the recording density and realizing good recording magnetic field sensitivity.

  In the first aspect of the present invention, preferably, each perpendicular magnetization film of the recording layer is formed under a lower gas pressure condition as the perpendicular magnetization film is closer to the nucleation layer. That is, each perpendicular magnetization film of the recording layer is formed under a higher gas pressure condition as the perpendicular magnetization film is farther from the nucleation layer. According to such a technique, it is possible to appropriately form the recording layer of the magneto-optical recording medium in which the perpendicular magnetic film closer to the nucleation layer has a denser film structure and the farther perpendicular magnetic film has a rougher film structure. .

  Preferably, each perpendicular magnetization film of the recording layer is thinner as the perpendicular magnetization film is closer to the nucleation layer. Such a configuration avoids an excessive superimposition of the pinning action derived from the film structure and the pinning action derived from the nucleation layer while obtaining a sufficient pinning action over the entire thickness of the recording layer. In addition, it is preferable.

  Preferably, the recording layer contains nitrogen, and each perpendicular magnetization film of the recording layer has a higher nitrogen composition ratio as the perpendicular magnetization film is closer to the nucleation layer. The nitridation of the perpendicular magnetization film tends to decrease the perpendicular magnetic anisotropy of the perpendicular magnetization film and weaken the domain wall coercive force of the perpendicular magnetization film. Therefore, this configuration is suitable for setting the perpendicular magnetization film closer to the nucleation layer in the recording layer so that the pinning action is weakened.

  According to the second aspect of the present invention, another magneto-optical recording medium is provided. This magneto-optical recording medium has a laminated structure comprising a recording layer made of a perpendicular magnetization film and a nucleation layer having a fine uneven surface on the recording layer side. In addition, the recording layer has a denser film structure as it is closer to the nucleation layer.

  In the recording layer of the magneto-optical recording medium of the second aspect, the portion closer to the nucleation layer has a dense film structure and tends to have fewer or fewer vacancies and voids. The closer to the site, the weaker the pinning effect derived from the membrane tissue. On the other hand, the recording layer also has a pinning action derived from the shape of the fine uneven surface (fine uneven shape) of the nucleation layer located immediately below the recording layer. This pinning effect occurs over the entire thickness of the recording layer, but the closer the portion of the recording layer is to the nucleation layer (fine irregular surface), the stronger the pinning effect.

  In the recording layer of the magneto-optical recording medium, the closer to the nucleation layer, the denser the membrane structure (therefore, the pinning action derived from the membrane structure is weaker), and the farther from the nucleation layer, the more Is set roughly (thus, the pinning action derived from the membrane tissue is strong). With such a configuration, the pinning effect derived from the film structure and the nucleation layer can be obtained at a site near the nucleation layer (fine irregular surface) in the recording layer while obtaining a sufficient pinning effect throughout the thickness of the recording layer. It is suitable for avoiding excessive superimposition with the derived pinning effect. By obtaining a sufficient pinning effect over the entire thickness of the recording layer, while avoiding excessive superposition of the pinning action derived from the film structure and the pinning action derived from the nucleation layer, the recording layer ( In the perpendicular magnetization film), it is possible to avoid the domain wall coercive force from becoming excessive, and to obtain a domain wall coercive force having sufficient strength but not excessive. Therefore, the magneto-optical recording medium according to the second aspect of the present invention is also suitable for increasing the recording density and realizing good recording magnetic field sensitivity, similarly to the magneto-optical recording medium according to the first aspect. is there.

  In the second aspect of the present invention, preferably, the recording layer is formed under a lower gas pressure condition at a portion closer to the nucleation layer. That is, the recording layer is formed under a higher gas pressure condition at a portion farther from the nucleation layer. According to such a technique, it is possible to appropriately form the recording layer of the magneto-optical recording medium in which the portion closer to the nucleation layer is denser in film structure and the portion farther away is rougher in film structure.

  Preferably, the recording layer contains nitrogen, and the portion closer to the nucleation layer has a higher nitrogen composition ratio. The nitriding of the recording layer tends to reduce the perpendicular magnetic anisotropy of the nitriding part and weaken the domain wall coercive force of the nitriding part. Therefore, this configuration is suitable for setting the pinning action to be weaker in the recording layer closer to the nucleation layer.

  In the first and second aspects of the present invention, preferably, the recording layer is made of TbFeCo, a Pt alloy, or a Pd alloy. These magnetic materials are suitable as the constituent material of the recording layer in the present invention.

  FIG. 1 is a partial sectional view of a magneto-optical disk X1 according to the first embodiment of the present invention. The magneto-optical disk X1 includes a substrate S, a recording magnetic part 10, a pregroove layer 21, a heat conduction layer 22, dielectric layers 23 and 25, a nucleation layer 24, and a protective film 26, and a front surface. It is configured as an illumination type magneto-optical disk. The magneto-optical disk X1 has a structure from the pre-groove layer 21 to the protective film 26 on only one side or both sides of the substrate S.

  The substrate S is a part for ensuring the rigidity of the magneto-optical disk X1, and is, for example, a disk substrate made of resin, silicon, aluminum, or glass.

  The recording magnetic unit 10 has a laminated structure composed of a recording layer 11, an intermediate layer 12, and a reproducing layer 13, and a magnetic domain expansion system reproducing system (for example, DWDD, MAMMOS, etc.) accompanied by domain wall movement or magnetic domain expansion in the reproducing layer 13 is used. ) Is configured to be reproducible based on.

  The recording layer 11 is a part responsible for a recording function in the magneto-optical disk X1, and is composed of internal structure layers 11a and 11b. The internal structure layers 11a and 11b are each a perpendicular magnetization film made of an amorphous alloy containing a rare earth element and a transition metal and magnetized in the perpendicular direction with perpendicular magnetic anisotropy. The vertical direction means a direction perpendicular to the film surface of the magnetic film constituting the layer. In the recording layer 11, the internal structure layer 11a has a relatively dense film structure, and the internal structure layer 11b has a relatively coarse film structure. Specifically, the film structure of the internal structure layer 11a is composed of relatively fine columnar grains and the pores and voids are relatively small or few, and the film structure of the internal structure layer 11b is relatively It consists of coarse grained columnar grains and has relatively large or many pores and voids. Within the recording layer 11, a single magnetic domain occurs across both internal structure layers 11a and 11b. Specifically, the internal structure layers 11a and 11b are made of a predetermined composition ratio such as TbFeCо, TbDyFeCо, PtCo, PdCo, or the like. Both internal structure layers 11a and 11b preferably have the same composition. Further, nitrogen for reducing the perpendicular magnetic anisotropy of the perpendicular magnetization film may be added to the internal structure layer 11a. The thickness of the internal structure layer 11a is, for example, 5 to 25 nm, and the thickness of the internal structure layer 11b is, for example, 10 to 60 nm as long as it is larger than the thickness of the internal structure layer 11a.

  The intermediate layer 12 is a part for changing the exchange coupling state of the recording layer 11 and the reproducing layer 13, and changes from the perpendicular magnetization state to the spontaneous magnetization disappearance state at the Curie temperature when the temperature rises, and the Curie temperature due to the temperature fall. It is made of a rare earth-transition metal amorphous alloy that transitions from a spontaneous magnetization disappearance state to a perpendicular magnetization state. In this embodiment, the Curie temperature of the intermediate layer 12 is, for example, 100 to 170 ° C. Therefore, the intermediate layer 12 is a perpendicular magnetization film at room temperature. Specifically, the intermediate layer 12 is made of, for example, TbFe or TbFeCо having a predetermined composition ratio. Moreover, the thickness of the intermediate layer 12 is, for example, 10 to 30 nm.

  The reproducing layer 13 is a part that bears a reproducing function accompanied by domain wall movement or domain expansion, and is a perpendicular magnetization film made of a rare earth-transition metal amorphous alloy. Specifically, the reproducing layer 13 is made of, for example, GdFeCo or GdDyFeCo having a predetermined composition ratio. The reproducing layer 13 has a thickness of 10 to 50 nm.

  The pregroove layer 21 is made of a resin material, and an uneven shape (not shown) such as a pregroove is formed on the contact surface with the heat conductive layer 22. The pregroove has a spiral or concentric pattern shape, and a land groove shape in the magneto-optical disk X1 is realized based on the pregroove. As a resin material constituting the pre-groove layer 21, for example, a resin for 2P method (photopolymer) can be employed. The thickness of the pregroove layer 21 is, for example, 5 to 25 μm.

  The heat conductive layer 22 is a part for efficiently transmitting heat generated in the recording magnetic unit 10 or the like to the substrate S side when the recording or reproducing laser is irradiated to the magneto-optical disk X1. For example, Ag, Ag alloy (AgPdCuSi, AgPdCu, etc.), Al alloy (AlN, AlSi, AlTi, AlCr, etc.), Au, or Pt. The thickness of the heat conductive layer 22 is, for example, 10 to 50 nm.

The dielectric layers 23 and 25 are parts for avoiding or suppressing an undue magnetic influence on the recording magnetic part 10 from the outside. For example, SiN, SiO ₂ , YSiO ₂ , ZnSiO ₂ , AlO, or AlN It becomes more. The thickness of the dielectric layers 23 and 25 is, for example, 5 to 100 nm.

  The nucleation layer 24 is provided on the dielectric layer 23 as a base film for forming the recording layer 11 immediately above the nucleation layer 24, and has a pinning effect on the recording layer 11 on the recording layer 11 side. It has a fine uneven surface 24a with a fine uneven shape for effect. The surface roughness Ra (arithmetic average roughness) of the fine uneven surface 24a is, for example, 0.5 to 2 nm, and the average height (average of the maximum height Ry) of the convex portions of the fine uneven surface 24a is, for example, 1 to 6 nm. is there. Such a nucleation layer 24 is made of, for example, Pt. The thickness of the nucleation layer 24 is, for example, 2 to 10 nm.

  The protective film 26 is made of a resin material that covers the recording magnetic part 10 in order to protect the recording magnetic part 10 from dust and the like, and has sufficient permeability to the recording laser and the reproducing laser of the magneto-optical disk X1. As the resin for forming the protective film 26, for example, an ultraviolet curable transparent resin is employed.

  FIG. 2 shows a method for manufacturing the magneto-optical disk X1. In this method, first, as shown in FIG. 2A, a pregroove layer 21, a heat conductive layer 22, and a dielectric layer 23 are sequentially formed on a substrate S. As a method for forming the pre-groove layer 21, a 2P method using a predetermined resin can be employed. Further, as a method for forming the heat conductive layer 22 and the dielectric layer 23, a sputtering method in which a predetermined material is formed using a predetermined sputtering apparatus and a predetermined target can be employed.

  Next, as shown in FIG. 2B, a nucleation layer 24 having a fine irregular surface 24a at the growth end is formed on the dielectric layer 23 by sputtering.

  Next, as shown in FIG. 2C, the recording layer 11 is formed on the nucleation layer 24. Specifically, the internal structure layers 11a and 11b are sequentially formed on the nucleation layer 24 by sputtering. In forming the internal structure layer 11a, a predetermined material is formed on the nucleation layer 24 under relatively low gas pressure conditions (gas pressure conditions in the chamber of the sputtering apparatus), and in forming the internal structure layer 11b, Preferably, the same material is deposited on the internal structure layer 11a under relatively high gas pressure conditions. In this way, the recording layer 11 including the internal structure layer 11a having a relatively dense film structure as described above and the internal structure layer 11b having a relatively coarse film structure as described above is formed. can do. In addition, when adding nitrogen to the internal structure layer 11a, when forming the internal structure layer 11a, a predetermined material is added in a gas atmosphere containing a predetermined concentration of nitrogen and under a relatively low gas pressure condition as described above. A film is formed on the nucleation layer 24.

  Next, as shown in FIG. 2D, the intermediate layer 12, the reproducing layer 13, the dielectric layer 25, and the protective film 26 are sequentially formed on the recording layer 11. As a method for forming the intermediate layer 12, the reproduction layer 13, and the dielectric layer 25, a sputtering method can be employed. The protective film 26 can be formed, for example, by depositing a transparent ultraviolet curable resin material on the dielectric layer 25 by spin coating and then irradiating the resin material with ultraviolet rays. The magneto-optical disk X1 can be manufactured as described above.

  In the information recording on the magneto-optical disk X1, for example, a continuous laser pulse signal is sent from the protective film 26 side to the recording magnetic unit 10 while the disk is rotated. As the recording layer 11 (internal structure layers 11a and 11b) in the recording magnetic part 10 is locally heated sequentially, a recording magnetic field modulated in a predetermined manner is applied to the temperature rising portion. (Not shown). Thereby, in the recording layer 11, a plurality of magnetic domains (record marks) whose magnetization directions are sequentially reversed are formed continuously in the circumferential direction or the track extending direction of the magneto-optical disk X1. In this manner, predetermined information or signals can be recorded on the recording layer 11 as changes in the magnetization direction.

  In the recording layer 11 of the magneto-optical disk X1, the internal structure layer 11a (perpendicular magnetization film) close to the nucleation layer 24 is denser than the internal structure layer 11b (perpendicular magnetization film) far from the nucleation layer 24. Therefore, the pinning action derived from the membrane structure is weak. On the other hand, the recording layer 11 also has a pinning action derived from the shape of the fine uneven surface 24a (fine uneven shape) of the nucleation layer 24 located immediately below it. This pinning action occurs over the entire thickness of the recording layer 11, but the portion closer to the nucleation layer 24 in the recording layer 11 has a stronger pinning action.

  In the recording layer 11 of the magneto-optical disk X1, the internal structure layer 11a close to the nucleation layer 24 is set to have a finer film structure than the internal structure layer 11b (therefore, the pinning action derived from the film structure is weak). Therefore, the pinning action derived from the film structure and the pinning action derived from the nucleation layer 24 are obtained in the vicinity of the nucleation layer 24 in the recording layer 11 while obtaining a sufficient pinning action over the entire thickness of the recording layer 11. It can be avoided that the superimposing action is excessive. By obtaining a sufficient pinning effect over the entire thickness of the recording layer 11, while avoiding an excessive superimposition of the pinning effect derived from the film structure and the pinning effect derived from the nucleation layer 24, recording is performed. In the layer 11, it is possible to avoid a domain wall coercive force from becoming excessive, and to obtain a domain wall coercive force having sufficient strength but not excessive. By realizing a sufficient strength with respect to the domain wall coercive force, it is possible to stabilize the minute magnetic domains in the recording layer 11 and increase the recording density. On the other hand, by realizing a strength that is not excessive with respect to the domain wall coercive force, it is possible to obtain a good recording magnetic field sensitivity by suppressing the strength of the recording magnetic field to be applied in order to form the stable minute magnetic domain. As described above, according to the magneto-optical disk X1, it is possible to achieve high recording density and good recording magnetic field sensitivity.

  FIG. 3 is a partial sectional view of a magneto-optical disk X2 according to the second embodiment of the present invention. The magneto-optical disk X2 includes a substrate S, a recording magnetic part 30, a pregroove layer 21, a heat conductive layer 22, dielectric layers 23 and 25, a nucleation layer 24, and a protective film 26. The magneto-optical disk is configured as an illumination type magneto-optical disk, and differs from the magneto-optical disk X1 in that a recording magnetic part 30 is provided in place of the recording magnetic part 10. The magneto-optical disk X2 has a structure from the pre-groove layer 21 to the protective film 26 on only one side or both sides of the substrate S.

  The recording magnetic unit 30 has a laminated structure composed of a recording layer 31, an intermediate layer 32, and a reproducing layer 33, and a magnetic domain expansion system reproducing system (for example, DWDD, MAMMOS, etc.) accompanied by domain wall movement or magnetic domain expansion in the reproducing layer 33. ) Is configured to be reproducible based on.

  The recording layer 31 is a part that bears a recording function in the magneto-optical disk X2, and includes internal structure layers 31a, 31b, and 31c. The internal structure layers 31a, 31b, and 31c are each a perpendicular magnetization film made of an amorphous alloy containing a rare earth element and a transition metal, and having perpendicular magnetic anisotropy and magnetized in the perpendicular direction. In the recording layer 31, the internal structure layer 31a has the finest film structure, the internal structure layer 31c has the roughest film structure, and the internal structure layer 31b is coarser than the internal structure layer 31a. It has a denser film structure than the internal structure layer 31c. Within the recording layer 31, a single magnetic domain occurs across the internal structure layers 31a, 31b, 31c. Specifically, the internal structure layers 31a, 31b, and 31c are made of a predetermined composition ratio such as TbFeCо, TbDyFeCо, PtCo, PdCo, or the like. All the internal structure layers 31a, 31b, 31c preferably have the same composition. Further, nitrogen may be added to the recording layer 31. When adding nitrogen to the recording layer 31, the nitrogen composition ratio of the internal structure layer 31a is set to be the highest, and the nitrogen composition ratio of the internal structure layer 31b is set to be the second highest. In this case, the nitrogen composition ratio of the internal structure layer 31c is set to the lowest or no nitrogen is added to the internal structure layer 31c. The thickness of the internal structure layer 31a is, for example, 5 to 15 nm, the thickness of the internal structure layer 31b is, for example, 10 to 30 nm as long as it is larger than the thickness of the internal structure layer 31a, and the thickness of the internal structure layer 31c is It is not less than the thickness of the internal structure layer 31b and is, for example, 10 to 50 nm. Preferably, the internal structure layer 31c is thicker than the internal structure layer 31b.

  The intermediate layer 32 and the reproducing layer 33 of the recording magnetic unit 30 are the same as those described above with respect to the intermediate layer 12 and the reproducing layer 13 of the recording magnetic unit 10 in the first embodiment.

  The magneto-optical disk X2 having the above configuration can be manufactured in the same manner as the magneto-optical disk X1 except that the recording layer 31 is formed instead of the recording layer 11.

  In forming the recording layer 31 of the magneto-optical disk X2, the internal structure layers 31a, 31b, and 31c are sequentially formed on the nucleation layer 24 by sputtering. In forming the internal structure layer 31a, a predetermined material is formed on the nucleation layer 24 under the lowest gas pressure condition, and preferably in the formation of the internal structure layer 31b, the same material is used in the second lowest gas pressure condition. In forming the internal structure layer 31c, the same material is preferably formed on the internal structure layer 31b under the highest gas pressure condition. In this way, the internal structure layer 31a having the finest film structure, the internal structure layer 31c having the roughest film structure, and the film structure rougher than the internal structure layer 31a and denser than the internal structure layer 31c are obtained. The recording layer 31 composed of the internal structure layer 31b can be formed. Further, when nitrogen is added to the internal structure layer 31a, a predetermined material is nucleated in the gas atmosphere containing a predetermined concentration of nitrogen and the lowest gas pressure condition as described above when forming the internal structure layer 31a. A film is formed on the layer 24. When nitrogen is added to the internal structure layer 31b, a gas atmosphere containing a lower concentration of nitrogen than the formation of the internal structure layer 31a and the second lowest gas as described above are formed when the internal structure layer 31b is formed. A predetermined material is deposited on the internal structure layer 31a under a pressure condition.

  In recording information on the magneto-optical disk X2, for example, a continuous laser signal is sent from the protective film 26 side to the recording magnetic unit 30 by a recording laser (not shown) while the disk is rotated. The recording layer 31 (internal structure layers 31a, 31b, 31c) in the recording magnetic unit 30 is locally heated in sequence, and a predetermined modulated recording magnetic field is magnetically applied to the temperature rising portion. Application is made by a recording head (not shown). In this way, predetermined information or signals can be recorded on the recording layer 31 as changes in the magnetization direction.

  In the recording layer 31 of the magneto-optical disk X2, the inner structure layer closer to the nucleation layer 24 has a denser film structure and tends to have smaller or fewer holes and voids. The closer the internal structure layer is, the weaker the pinning effect derived from the membrane structure. On the other hand, the recording layer 31 also has a pinning action derived from the shape of the fine uneven surface 24a (fine uneven shape) of the nucleation layer 24 located immediately below. This pinning action occurs over the entire thickness of the recording layer 31, but the pinning action is stronger in the recording layer 31 at a portion closer to the nucleation layer 24.

  In the recording layer 31 of the magneto-optical disk X2, the closer the internal structure layer is to the nucleation layer 24, the denser the film structure (and hence the weaker the pinning action derived from the film structure), and the farther from the nucleation layer 24. Since the inner structure layer is set to have a rougher film structure (thus, the pinning action derived from the film structure is stronger), the core in the recording layer 31 is obtained while obtaining a sufficient pinning action over the entire thickness of the recording layer 31. It is possible to avoid that the superimposing action of the pinning action derived from the film structure and the pinning action derived from the nucleation layer 24 becomes excessive at a site in the vicinity of the formation layer 24. By obtaining a sufficient pinning effect over the entire thickness of the recording layer 31, while avoiding an excessive superimposition of the pinning effect derived from the film structure and the pinning effect derived from the nucleation layer 24, recording is performed. In the layer 31, it is possible to avoid the domain wall coercive force from becoming excessive, and to obtain a domain wall coercive force having sufficient strength but not excessive. Therefore, according to the magneto-optical disk X2, as with the magneto-optical disk X1, it is possible to achieve a high recording density and to achieve a good recording magnetic field sensitivity.

  FIG. 4 is a partial cross-sectional view of a magneto-optical disk X3 according to the third embodiment of the present invention. The magneto-optical disk X3 includes a substrate S, a recording magnetic part 40, a pregroove layer 21, a heat conductive layer 22, dielectric layers 23 and 25, a nucleation layer 24, and a protective film 26, and a front surface. The magneto-optical disk is configured as an illumination type magneto-optical disk, and differs from the magneto-optical disk X1 in that a recording magnetic unit 40 is provided in place of the recording magnetic unit 10. The magneto-optical disk X3 has a structure from the pre-groove layer 21 to the protective film 26 on only one side or both sides of the substrate S.

  The recording magnetic unit 40 has a laminated structure composed of a recording layer 41, an intermediate layer 42, and a reproducing layer 43, and a magnetic domain expansion system reproducing method (for example, DWDD, MAMMOS, etc.) accompanied by domain wall movement or magnetic domain expansion in the reproducing layer 43. ) Is configured to be reproducible based on.

  The recording layer 41 is a part responsible for the recording function in the magneto-optical disk X3, and is made of an amorphous alloy containing a rare earth element and a transition metal, and has perpendicular magnetic anisotropy and is perpendicularly magnetized in the perpendicular direction. It is a membrane. In addition, the recording layer 41 has a dense film structure at a portion closer to the nucleation layer 24 and a rough film structure at a portion farther from the nucleation layer 24. Specifically, the recording layer 41 is made of a predetermined composition ratio such as TbFeCо, TbDyFeCо, PtCo, PdCo, or the like. Further, nitrogen may be added to the recording layer 41. When nitrogen is added to the recording layer 41, the portion closer to the nucleation layer 24 is set to a higher nitrogen composition ratio. The thickness of the recording layer 41 is, for example, 15 to 90 nm.

  The intermediate layer 42 and the reproducing layer 43 of the recording magnetic unit 40 are the same as those described above with respect to the intermediate layer 12 and the reproducing layer 13 of the recording magnetic unit 10 in the first embodiment.

  The magneto-optical disk X3 having the above configuration can be manufactured in the same manner as the magneto-optical disk X1 except that the recording layer 41 is formed instead of the recording layer 11.

  In forming the recording layer 41 of the magneto-optical disk X3, a predetermined material is formed on the nucleation layer 24 by changing the gas pressure condition continuously from the low gas pressure condition to the high gas pressure condition by sputtering. To do. In this way, it is possible to form the recording layer 41 having a denser film structure at a portion closer to the nucleation layer 24. In addition, when adding nitrogen to the recording layer 41, the nitrogen concentration in the chamber of the sputtering apparatus is continuously changed from a high concentration to a low concentration and, as described above, from a low gas pressure condition to a high gas A predetermined material is formed on the nucleation layer 24 while continuously changing the gas pressure condition to the pressure condition.

  In recording information on the magneto-optical disk X3, for example, a continuous laser pulse signal is sent from the protective film 26 side to the recording magnetic unit 40 with a recording laser (not shown) while the disk is rotated. The recording layer 41 in the recording magnetic unit 40 is locally heated in sequence, and a predetermined modulated recording magnetic field is applied to the temperature rising portion by a magnetic recording head (not shown). . In this way, predetermined information or signals can be recorded on the recording layer 41 as changes in the magnetization direction.

  In the recording layer 41 of the magneto-optical disk X3, the portion closer to the nucleation layer 24 has a dense film structure and tends to have fewer or fewer vacancies and voids. The pinning effect derived from the membrane tissue is weak. On the other hand, the recording layer 41 also has a pinning action derived from the shape of the fine uneven surface 24a (fine uneven shape) of the nucleation layer 24 located immediately below it. This pinning action occurs over the entire thickness of the recording layer 41, but the pinning action is stronger in the recording layer 41 closer to the nucleation layer 24.

  In the recording layer of the magneto-optical disk X3, the closer to the nucleation layer 24, the denser the membrane structure (therefore, the pinning action derived from the film tissue is weaker), and the farther from the nucleation layer 24, Since the film structure is set roughly (and therefore the pinning action derived from the film structure is strong), a sufficient pinning action is obtained over the entire thickness of the recording layer 41, and the nucleation layer 24 in the vicinity of the nucleation layer 24 is obtained. It is possible to avoid an excessive superimposition of the pinning action derived from the membrane tissue and the pinning action derived from the nucleation layer 24 at the site. By obtaining a sufficient pinning effect over the entire thickness of the recording layer 41, it is possible to avoid an excessive superimposition of the pinning effect derived from the film structure and the pinning effect derived from the nucleation layer 24 by recording. In the layer 41, it is possible to avoid a domain wall coercive force from becoming excessive, and to obtain a domain wall coercive force having a sufficient strength that is not excessive. Therefore, according to the magneto-optical disk X3, similarly to the magneto-optical disks X1 and X2, it is possible to achieve a high recording density and to realize a good recording magnetic field sensitivity.

[Production of magneto-optical disk]
A magneto-optical disk of this example was manufactured as a front-illuminated magneto-optical disk having the laminated structure shown in FIG.

  In the production of the magneto-optical disk of this example, first, a pregroove layer having a thickness of 10 μm was formed on a glass substrate (diameter 120 mm, thickness 1.2 mm) by the 2P method. As the pregroove layer forming material, a resin for 2P method (photopolymer) was employed. Further, the surface irregularity shape of the pregroove layer was a land groove shape with a track pitch of 300 nm and a pregroove depth of 50 nm.

  Next, a 30 nm thick thermal conductive layer was formed by depositing AlSi on the pregroove layer by sputtering. Specifically, AlSi was formed on the pregroove layer by co-sputtering using an Al target and an Si target. In this sputtering, Ar is used as a sputtering gas (except for reactive sputtering, the same applies to the following sputtering in this embodiment), the sputtering gas pressure is 0.6 Pa, and the sputtering power is 0.3 kW (Al target). And 0.2 kW (Si target).

Next, a dielectric layer having a thickness of 15 nm was formed by depositing SiN on the heat conductive layer by sputtering. Specifically, SiN was formed on the heat conductive layer by reactive sputtering performed using an Si target and using Ar gas and N ₂ gas as sputtering gas. In this sputtering, the flow ratio of Ar gas and N ₂ gas was 7: 3, the sputtering gas pressure was 0.5 Pa, and the sputtering power was 0.8 kW.

  Next, a nucleation layer having a thickness of 3 nm having a fine uneven surface on the surface was formed by depositing Pt on the dielectric layer by a sputtering method. The surface roughness (arithmetic average roughness) Ra of the fine uneven surface of this nucleation layer was 1.0 nm, and the average height (average of the maximum height Ry) of the convex portions of the fine uneven surface was 1.5 nm. It was. In this sputtering, a Pt target was used, the sputtering gas pressure was 0.5 Pa, and the sputtering power was 0.5 kW.

Next, a recording layer was formed on the nucleation layer. Specifically, first, a Tb ₂₀ Fe ₆₅ Co ₁₅ film was formed on the nucleation layer by sputtering, thereby forming a first internal structure layer having a thickness of 10 nm. In this sputtering, Tb ₂₀ Fe ₆₅ Co ₁₅ was formed on the nucleation layer by co-sputtering using a Tb target and an FeCo alloy target. In this sputtering, the sputtering gas pressure was 0.4 Pa, and the sputtering power was 0.5 kW (Tb target) and 1.5 kW (FeCo alloy target). Thereafter, a second internal structure layer having a thickness of 40 nm was formed by further depositing Tb ₂₀ Fe ₆₅ Co ₁₅ on the first internal structure layer by a sputtering method. In this sputtering, Tb ₂₀ Fe ₆₅ Co ₁₅ is formed on the first internal structure layer by co-sputtering using a Tb target and an FeCo alloy target, the sputtering gas pressure is set to 3.0 Pa, and the sputtering power is set to 0.3. 5 kW (Tb target) and 1.5 kW (FeCo alloy target). In this way, the recording layer in this example was formed on the nucleation layer. The configuration of this recording layer and the gas pressure conditions when forming the recording layer are listed in the table of FIG. The configuration of the recording layer and the gas pressure conditions in the following examples and comparative examples are also listed in the table of FIG.

Next, an intermediate layer having a thickness of 15 nm was formed by depositing Tb ₂₂ Fe ₇₈ on the recording layer by sputtering. Specifically, Tb ₂₂ Fe ₇₈ was formed on the recording layer by co-sputtering using a Tb target and an Fe target. In this sputtering, the sputtering gas pressure was 1.0 Pa, and the sputtering power was 0.3 kW (Tb target) and 0.9 kW (Fe target).

Next, a reproducing layer having a thickness of 25 nm was formed by depositing Gd ₂₅ Fe ₇₀ Co ₅ on the intermediate layer by sputtering. Specifically, Gd ₂₅ Fe ₇₀ Co ₅ was formed on the intermediate layer by co-sputtering using a Gd target and an FeCo alloy target. In this sputtering, the sputtering gas pressure was 0.4 Pa, and the sputtering power was 0.4 kW (Gd target) and 0.8 kW (FeCo alloy target).

Next, a dielectric layer having a thickness of 60 nm was formed by depositing SiN on the reproducing layer by sputtering. Specifically, SiN was formed on the reproduction layer by reactive sputtering using an Si target and using Ar gas and N ₂ gas as sputtering gas. In this sputtering, the flow ratio of Ar gas and N ₂ gas was 7: 3, the sputtering gas pressure was 0.5 Pa, and the sputtering power was 0.8 kW.

  Next, a protective film having a thickness of 20 μm was formed on the dielectric layer. Specifically, first, an ultraviolet curable transparent resin was applied on the dielectric layer by spin coating. Next, the resin film was cured by ultraviolet irradiation. As described above, the magneto-optical disk of this example was manufactured.

[Measurement of recording magnetic field and CNR]
For the magneto-optical disk of this example, the minimum required recording magnetic field strength and the CNR of the reproduction signal were examined. Specifically, the minimum magnetic field is specified from among the magnetic fields applied by the magnetic recording head that can record information on the magneto-optical disk so that the intensity (CNR) of the reproduction signal is saturated, and the minimum The intensity of the magnetic field formed on the medium surface when a magnetic field was applied was measured with a gauss meter as the intensity of the recording magnetic field formed so as to pass through the recording layer. Information recording was performed by repeatedly forming a recording mark having a mark length of 80 nm through a space having a length of 80 nm in the magnetic field modulation recording method. The intensity of the recording magnetic field measured in this way was 400 Oe. The CNR of the reproduction signal when information recording was performed with this recording magnetic field strength was 39 dB. These values are listed in the table of FIG. The values of the recording magnetic field and the CNR value of the reproduction signal in the following examples and comparative examples are also listed in the table of FIG.

  A magneto-optical disk of this example was produced in the same manner as in Example 1 except for the formation of the recording layer. The recording layer in this example was the same as that in Example 1 except that the thickness of the first internal structure layer was changed to 5 nm instead of 10 nm, and the thickness of the second internal structure layer was changed to 45 nm instead of 40 nm. Formed in the same way as the layer. For the magneto-optical disk of this example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 600 Oe and the CNR was 40 dB.

  A magneto-optical disk of this example was produced in the same manner as in Example 1 except for the formation of the recording layer. The recording layer in this example is the same as that in Example 1 except that the thickness of the first internal structure layer is 15 nm instead of 10 nm, and the thickness of the second internal structure layer is 35 nm instead of 40 nm. Formed in the same way as the layer. For the magneto-optical disk of this example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 350 Oe, and the CNR was 38 dB.

  A magneto-optical disk of this example was produced in the same manner as in Example 1 except for the formation of the recording layer. The recording layer in this example was formed in the same manner as the recording layer in Example 1 except that the sputtering gas pressure when forming the first internal structure layer was changed to 1.0 Pa instead of 0.4 Pa. For the magneto-optical disk of this example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. As a result, the recording magnetic field strength was 600 Oe and the CNR was 39 dB.

  A magneto-optical disk of this example was produced in the same manner as in Example 1 except for the formation of the recording layer. The recording layer in this example was formed in the same manner as the recording layer in Example 1 except that the sputtering gas pressure when forming the first internal structure layer was set to 2.0 Pa instead of 0.4 Pa. For the magneto-optical disk of this example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. As a result, the recording magnetic field strength was 700 Oe and the CNR was 39 dB.

A magneto-optical disk of this example was produced in the same manner as in Example 1 except for the formation of the recording layer. The recording layer in this example was formed in the same manner as the recording layer in Example 1 except that Ar containing a predetermined concentration of N ₂ was used as the sputtering gas for forming the first internal structure layer. The first internal structure layer in this example contains 5 at% (atomic percent) of nitrogen. For the magneto-optical disk of this example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 300 Oe, and the CNR was 37 dB.

Comparative Example 1

[Production of magneto-optical disk]
A magneto-optical disk of this comparative example was manufactured as a front-illuminated magneto-optical disk having the laminated structure shown in FIG.

  In the production of the magneto-optical disk of this comparative example, first, in the same manner as in Example 1, a pregroove layer (thickness 10 μm) and a heat conduction layer (thickness 120 μm, thickness 1.2 mm) A thickness of 30 nm), a dielectric layer (thickness of 15 nm), and a nucleation layer (thickness of 3 nm) were sequentially formed.

Next, Tb ₂₀ Fe ₆₅ Co ₁₅ was deposited on the nucleation layer by sputtering to form a recording layer having a thickness of 50 nm. In this sputtering, Tb ₂₀ Fe ₆₅ Co ₁₅ was formed on the nucleation layer by co-sputtering using a Tb target and an FeCo alloy target. In this sputtering, the sputtering gas pressure was set to 3.0 Pa, and the sputtering power was set to 0.5 kW (Tb target) and 1.5 kW (FeCo alloy target). The film structure of the recording layer formed in this way is substantially uniform.

  Thereafter, an intermediate layer (thickness 15 nm), a reproduction layer (thickness 25 nm), a dielectric layer (thickness 60 nm), and a protective film (thickness 20 μm) are formed on the recording layer in the same manner as in Example 1. Were sequentially formed. As described above, the magneto-optical disk of this comparative example was produced.

[Measurement of recording magnetic field and CNR]
For the magneto-optical disk of this comparative example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 800 Oe and the CNR was 40 dB.

Comparative Example 2

  A magneto-optical disk of this comparative example was fabricated in the same manner as in Comparative Example 1 except that the sputtering gas pressure during formation of the recording layer was changed to 0.4 Pa instead of 3.0 Pa. The film structure of the recording layer in this comparative example is also substantially uniform, like the recording layer in comparative example 1. For the magneto-optical disk of this comparative example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 250 Oe, and the CNR was 25 dB.

Comparative Example 3

  A magneto-optical disk of this comparative example was produced in the same manner as in Example 1 except for the formation of the recording layer. In the recording layer in this comparative example, the thickness of the first internal structure layer is changed to 40 nm instead of 10 nm, and the sputtering gas pressure when forming the first internal structure layer is set to 3.0 Pa instead of 0.4 Pa. Recording in Example 1 except that the thickness of the second internal structure layer was changed to 10 nm instead of 40 nm, and the sputtering gas pressure when forming the second internal structure layer was changed to 0.4 Pa instead of 3.0 Pa. Formed in the same way as the layer. For the magneto-optical disk of this comparative example, the recording magnetic field strength and the reproduction signal CNR were examined in the same manner as in Example 1. The recording magnetic field strength was 350 Oe, and the CNR was 35 dB.

Evaluation

  As shown in the table of FIG. 6, the magneto-optical disks of Examples 1 to 6 according to the present invention are superior to the magneto-optical disk of Comparative Example 1 in recording magnetic field sensitivity. The minimum required recording magnetic field of the magneto-optical disk of Comparative Example 1 in which the recording layer is formed under relatively high uniform gas pressure conditions is as high as 800 Oe. On the other hand, Example 1 in which the recording layer is composed of a first internal structure layer formed under a relatively low gas pressure condition and a second internal structure layer formed under a relatively high gas pressure condition. In the magneto-optical disks of -6, the necessary minimum recording magnetic field was as low as 700 Oe or less, and good recording sensitivity was obtained.

  On the other hand, the magneto-optical disks of Examples 1 to 6 according to the present invention exhibit higher CNR than the magneto-optical disks of Comparative Examples 2 and 3. The CNR of the magneto-optical disk of Comparative Example 2 in which the recording layer is formed under a relatively low uniform gas pressure condition is too low at 25 dB. Further, the light of Comparative Example 3 in which the recording layer is constituted by the first internal structure layer formed under a relatively high gas pressure condition and the second internal structure layer formed under a relatively low gas pressure condition. The CNR of the magnetic disk is too low at 35 dB. On the other hand, Example 1 in which the recording layer is composed of a first internal structure layer formed under a relatively low gas pressure condition and a second internal structure layer formed under a relatively high gas pressure condition. In the magneto-optical disks of -6, good reproduction characteristics were obtained for recording marks having a CNR of 37 or more and a mark length as short as 80 nm. In the magneto-optical disks of Examples 1 to 6 in which good reproduction characteristics can be obtained in short mark recording, information recording at a high recording density is possible.

  As described above, in the magneto-optical disks of Examples 1 to 6 according to the present invention, it was possible to achieve high recording density and good recording magnetic field sensitivity.

  As a summary of the above, the configurations of the present invention and variations thereof are listed below as supplementary notes.

(Supplementary note 1) a recording layer having a laminated structure composed of a plurality of perpendicular magnetization films;
A nucleation layer having a fine irregular surface on the recording layer side,
Each perpendicular magnetization film of the recording layer has a denser film structure as the perpendicular magnetization film is closer to the nucleation layer.
(Supplementary note 2) The magneto-optical recording medium according to supplementary note 1, wherein each perpendicular magnetization film of the recording layer is formed under a lower gas pressure condition as the perpendicular magnetization film is closer to the nucleation layer.
(Appendix 3) The magneto-optical recording medium according to appendix 1 or 2, wherein each perpendicular magnetization film of the recording layer is thinner as a perpendicular magnetization film closer to the nucleation layer.
(Appendix 4) The recording layer according to any one of appendices 1 to 3, wherein the recording layer includes nitrogen, and each perpendicular magnetization film of the recording layer has a higher nitrogen composition ratio as the perpendicular magnetization film is closer to the nucleation layer. Magneto-optical recording medium.
(Appendix 5) A recording layer made of a perpendicular magnetization film;
A nucleation layer having a fine irregular surface on the recording layer side,
The magneto-optical recording medium, wherein the recording layer has a denser film structure closer to the nucleation layer.
(Supplementary note 6) The magneto-optical recording medium according to supplementary note 5, wherein the recording layer is formed under a lower gas pressure condition in a portion closer to the nucleation layer.
(Supplementary note 7) The magneto-optical recording medium according to supplementary note 5 or 6, wherein the recording layer contains nitrogen, and a portion closer to the nucleation layer has a higher nitrogen composition ratio.
(Supplementary note 8) The magneto-optical recording medium according to any one of supplementary notes 1 to 7, wherein the recording layer is made of TbFeCo, a Pt alloy, or a Pd alloy.

1 is a partial cross-sectional view of a magneto-optical disk according to a first embodiment of the present invention. 1 represents a method for manufacturing the magneto-optical disk shown in FIG. It is a fragmentary sectional view of the magneto-optical disk which concerns on the 2nd Embodiment of this invention. It is a fragmentary sectional view of the magneto-optical disk which concerns on the 3rd Embodiment of this invention. A common laminated structure is shown in the magneto-optical disks of Examples 1 to 5 and Comparative Examples 1 to 3. 6 is a table summarizing the recording layer configurations, sputtering gas pressures during recording layer formation, and recording magnetic field and CNR measurement results in the magneto-optical disks of Examples 1 to 6 and Comparative Examples 1 to 3. It is a partial sectional view of a conventional magneto-optical disk. It is a fragmentary sectional view of the conventional magneto-optical disk which has a nucleation layer.

Explanation of symbols

X1, X2, X3, X4 Magneto-optical disk S substrate 10, 30, 40, 71 Recording magnetic part 11, 31, 41 Recording layer 12, 32, 42 Intermediate layer 13, 33, 43 Reproduction layer 21, 72 Pregroove layer 22 , 73 Thermal conductive layer 23, 25, 74, 75 Dielectric layer 24, 77 Nucleation layer 24a, 77a Fine uneven surface 26, 76 Protective film

Claims (5)

A recording layer having a laminated structure composed of a plurality of perpendicular magnetization films;
A nucleation layer having a fine irregular surface on the recording layer side,
Each perpendicular magnetization film of the recording layer has a denser film structure as the perpendicular magnetization film is closer to the nucleation layer.   2. The magneto-optical recording medium according to claim 1, wherein each perpendicular magnetization film of the recording layer is formed under a lower gas pressure condition as the perpendicular magnetization film is closer to the nucleation layer.   The magneto-optical recording medium according to claim 1, wherein each perpendicular magnetization film of the recording layer is thinner as a perpendicular magnetization film closer to the nucleation layer.   4. The magneto-optical device according to claim 1, wherein the recording layer contains nitrogen, and each perpendicular magnetization film of the recording layer has a higher nitrogen composition ratio as the perpendicular magnetization film is closer to the nucleation layer. 5. recoding media. A recording layer made of a perpendicular magnetization film;
A nucleation layer having a fine irregular surface on the recording layer side,
The magneto-optical recording medium, wherein the recording layer has a denser film structure closer to the nucleation layer.

Images