In-plane Magnetization Layer Patents (Class 369/13.43)
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Patent number: 7399539Abstract: A magneto-optic recording medium has a stacked structure composed of a memory layer, a domain wall displacement layer having domain wall-resistant magnetism smaller than the memory layer, and a switching layer having a lower Curie temperature than these layers interposed between these layers. A recording surface of the magneto-optic recording medium is divided into a plurality of tracks of a predetermined track pitch. A domain wall displacement layer has a recording track region limited in a track width direction in a central portion of each track. A magnetized state of a vertically magnetized memory layer is only transferred in the recording track region. A buffer region is magnetically oriented in an in-plane direction at a predetermined temperature or lower and is vertically magnetized at the predetermined temperature or higher.Type: GrantFiled: December 6, 2004Date of Patent: July 15, 2008Assignee: Canon Kabushiki KaishaInventor: Tsutomu Shiratori
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Patent number: 7173884Abstract: A first dielectric layer 3, a multilayer magnetic film 10 in which a first magnetic layer 4 having perpendicular magnetic anisotropy at room temperature, a second magnetic layer 5 having inplane magnetic anisotropy at room temperature, and a third magnetic layer 6 having perpendicular magnetic anisotropy at room temperature are sequentially laminated, a second dielectric layer 7, a reflective layer 8, and a protective layer 9 are sequentially laminated onto one principal plane of a disk substrate 2 on which a land and a groove exist, thereby forming a magnetooptic disk 1. Saturation magnetization of the second magnetic layer 5 is set to a range from 8.80×10?2 to 1.76×10?1 Wb/m2. A gas pressure upon film creation of the second magnetic layer is set to a range from 0.6 to 3.0 Pa. A content ratio of Co in the third magnetic layer 6 is set to a range from 15 to 17 atom %.Type: GrantFiled: May 14, 2002Date of Patent: February 6, 2007Assignee: Sony CorporationInventors: Yutaka Wada, Hiroshi Nakayama
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Patent number: 7050361Abstract: A magneto-optical storage medium that protects against the effects of cross-talk, making it possible to further reduce the level of track density, and which also makes it possible to conduct high-density recording/playback with a reduced magnetic field for erasure and a favorable level of playback signal quality. More specifically, a magneto-optical storage medium, which includes at least the following laminated layers, in the following order: a playback layer, a non-magnetic layer, a transfer layer, a cut-off layer, and a recording layer. The playback layer preferably displays easy in-plane magnetization characteristics within the monolayer at room temperature, and the transfer layer and the recording layer each have easy magnetization characteristics in the vertical direction of the monolayers at room temperature when each layer is considered as a monolayer.Type: GrantFiled: March 22, 2002Date of Patent: May 23, 2006Assignee: Fujitsu LimitedInventor: Tetsuo Hosokawa
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Patent number: 6811889Abstract: A magneto-optical recording medium including a recording layer for recording information and a substrate for supporting the recording layer is disclosed. The recording layer includes: a recording magnetic film for recording the information, the recording magnetic film being formed of a perpendicular magnetic anisotropy film; and a readout magnetic film for optically reading out the information, the readout magnetic film being capable of being magnetically coupled with the recording magnetic film by an exchange-coupling force. The composition of the readout magnetic film may be chosen such that the exchange coupling force from the recording magnetic film does not affect the magnetization around the surface of the readout magnetic film on the side on which the readout light is incident.Type: GrantFiled: April 12, 2002Date of Patent: November 2, 2004Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Yoshihiko Kudoh, Yasumori Hino, Yuuichi Fukamachi, Masahiro Birukawa
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Patent number: 6767656Abstract: A magneto-optical recording medium comprising four magnetic layers including a mask layer, a reproduction layer, an intermediate layer and a recording layer, wherein the reproduction layer and the recording layer each have a direction of easy magnetization extending in a layer stacking direction at room temperature, the mask layer and the intermediate layer each have a direction of easy magnetization extending in an in-plane direction at room temperature, the mask layer, the reproduction layer, the intermediate layer and the recording layer have Curie temperatures Tc1, Tc2, Tc3 and Tc4, respectively, which satisfy relationships of Tc3<Tc2, Tc3<Tc4 and Tc3<Tc1, and the intermediate layer is a rare-earth-rich magnetic layer.Type: GrantFiled: March 15, 2001Date of Patent: July 27, 2004Assignee: Fujitsu LimitedInventor: Tsutomu Tanaka
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Patent number: 6754140Abstract: A magneto-optical recording medium for recording and reproducing data through light irradiation on a magnetic film side of the medium, the medium including at least one magnetic film which is formed on a substrate and has an easy axis of magnetization in a perpendicular direction and an in-plane magnetic film which is formed between the substrate and the magnetic film and has an easy axis of magnetization in an in-plane direction.Type: GrantFiled: September 25, 2001Date of Patent: June 22, 2004Assignee: Fujitsu LimitedInventor: Tsutomu Tanaka
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Patent number: 6707766Abstract: A magneto-optical storage medium includes an interference layer, a magnetic domain expansion layer, an intermediate layer, a magnetic masking layer, a recording layer, and a protection layer which are sequentially formed on a substrate. The magnetic domain expansion layer produces a smaller frictional force due to wall coercivity than do the other magnetic layers. The intermediate layer has the Curie temperature TC2 which is lower than those of the other magnetic layers. The magnetic masking layer is in a perpendicular magnetization state at temperatures that are in a proximity of TC2, and changes into an in-plane magnetization state at temperatures that are higher than the proximity of TC2. The recording layer produces a higher coercive force than those produced by the magnetic domain expansion layer at room temperature.Type: GrantFiled: March 19, 2002Date of Patent: March 16, 2004Assignee: Sharp Kabushiki KaishaInventors: Go Mori, Naoyasu Iketani, Michinobu Mieda, Akira Takahashi
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Patent number: 6671234Abstract: A magneto-optical storage medium includes: a reproduction magnetic layer exhibiting in-plane magnetization at room temperature and changing to perpendicular magnetization at a critical temperature or higher; first and second in-plane magnetized layers with Curie temperatures in a proximity of the critical temperature and exhibiting mutually opposite magnetic polarities; and a recording magnetic layer fabricated from a perpendicularly magnetized film, the reproduction magnetic layer, the first and second in-plane magnetized layers, and the recording magnetic layer being sequentially deposited, wherein the reproduction magnetic layer is exchange-coupled with the first and second in-plane magnetized layers at least at room temperature.Type: GrantFiled: June 28, 2000Date of Patent: December 30, 2003Assignee: Sharp Kabushiki KaishaInventors: Junji Hirokane, Noboru Iwata
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Patent number: 6671233Abstract: A magneto-optical recording medium comprises, on a substrate, a dielectric layer, a GdFeCo reproducing layer, a non-magnetic layer, and a TbFeCo recording layer. Upon reproduction, a DC magnetic field Hex is applied in the recording direction, and a reproducing light beam is radiated while being modulated to have a low power and a high power in synchronization with a reproducing clock. The reproducing layer is a magnetic film which changes from in-plane magnetization into perpendicular magnetization at a critical temperature Tcr, which has a compensation temperature Tcomp between room temperature and a Curie temperature Tc, and which satisfies Troom<Tcr<Tcomp<Tco<Tc in relation to a Curie temperature Tco of the recording layer. Magnetic domain transfer and magnetic domain magnification occur if the transfer magnetic field of the recording layer and the coercive force of the reproducing layer have the relationship of relative magnitude as shown in FIG.Type: GrantFiled: July 25, 2000Date of Patent: December 30, 2003Assignee: Hitachi Maxell, Ltd.Inventors: Katsusuke Shimazaki, Yoshitane Tsuburaya, Norio Ohta, Hitoshi Watanabe, Hiroki Takao
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Patent number: 6638597Abstract: In order to improve reproduction characteristics of a magneto-optical recording medium in a case of being subject to a magnetically induced super resolution readout process utilizing a blue-violet laser beam, there is provided a magneto-optical recording medium having a surface roughness of 0.3 nm or less on a surface of a substrate on which recording/reproduction magnetic layers are formed or a surface of a dielectric film formed on the substrate.Type: GrantFiled: October 26, 2000Date of Patent: October 28, 2003Assignee: Sony CorporationInventors: Masataka Shinoda, Yasuhito Tanaka, Takashi Shimouma
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Patent number: 6630252Abstract: An MO disk includes a readout layer, an intermediate layer and a recording layer each of which is made of a rare earth-transition metal amorphous material. The MO disk also includes a fourth magnetic layer formed on the recording layer and made of a rare earth-transition metal amorphous magnetic material containing Gd. The fourth magnetic layer has a rare earth metal magnetization-dominant composition and an axis of easy magnetization oriented longitudinally at room temperature. The axis of easy magnetization is changed to be oriented perpendicularly to the fourth magnetic layer as the temperature of the fourth magnetic layer rises to the Curie temperature of the fourth magnetic layer.Type: GrantFiled: July 28, 2000Date of Patent: October 7, 2003Assignee: Fujitsu LimitedInventor: Toshio Sugimoto
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Publication number: 20030107956Abstract: A magneto-optical recording medium 11 is irradiated with a reproducing light beam 13 so that only a minute magnetic domain 313b, which is subjected to recording in a recording layer 18 and which is smaller than ½ of a spot radius of the recording light beam 13, is selected by a gate layer 17 and transferred to a magnetic domain-magnifying and reproducing layer 3. The magnetic domain transferred to the magnetic domain-magnifying and reproducing layer 3 is magnified by using a magnifying and reproducing magnetic field 411 of an alternating magnetic field. A large reproduction signal is obtained from the magnified magnetic domain 419, and the minute magnetic domain can be subjected to reproduction at a high resolving power and at a high S/N ratio. The magnified magnetic domain 419 is reduced by using a reducing reproducing magnetic field 415 of the alternating magnetic field. The gate layer 17 has a thickness which is not less than a thickness of a magnetic wall of the magnetic domain.Type: ApplicationFiled: November 25, 2002Publication date: June 12, 2003Applicants: Hitachi Maxwell, Ltd., Sanyo Electric Co., Ltd.Inventors: Hiroyuki Awano, Hiroshi Shirai, Masafumi Yoshihiro, Satoru Oonuki, Norio Ohta, Katsusuke Shimazaki, Nobuyuki Nagai, Satoshi Sumi, Atsushi Yamaguchi
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Publication number: 20030081510Abstract: A magneto-optical recording medium is composed of a base which has a property that a light can be transmitted therethrough, a readout layer formed on the base, which has in-plane magnetization at room temperature, whereas, a transition occurs from in-plane magnetization to perpendicular magnetization as the temperature thereof is raised and a recording layer formed on the readout layer for recording information magneto-optically. A recording and reproducing method and the optical head are designed for the magneto-optical recording medium. By the recording and reproducing method using the optical head, information recorded at high density can be reproduced.Type: ApplicationFiled: August 8, 2002Publication date: May 1, 2003Applicant: Sharp Kabushiki KaishaInventors: Yoshiteru Murakami, Junji Hirokane, Junichiro Nakayama, Junsaku Nakajima, Akira Takahashi, Kenji Ohta, Naoyasu Iketani
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Patent number: 6545955Abstract: The magneto-optical storage medium includes: a reproduction layer exhibiting in-plane magnetization at room temperature and changing to perpendicular magnetization above a transition temperature Tp1; a first in-plane magnetized layer disposed adjacent the reproduction layer and constituted by an in-plane magnetized film having a Curie temperature Tc2 around the transition temperature Tp1; a storage layer constituted by a perpendicularly magnetized film for storing information; and at least one supplementary reproduction section, interposed between the storage layer and the first in-plane magnetized layer, constituted by a first supplementary reproduction layer and a second in-plane magnetized layer, the first supplementary reproduction layer exhibiting in-plane magnetization at room temperature and changing to perpendicular magnetization above a transition temperature Tp3, the second in-plane magnetized layer being disposed adjacent the first supplementary reproduction layer and constituted by an in-plaType: GrantFiled: July 28, 2000Date of Patent: April 8, 2003Assignee: Sharp Kabushiki KaishaInventors: Noboru Iwata, Junji Hirokane
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Patent number: 6534162Abstract: A magneto-optical recording medium includes at least: a reproducing magnetic layer composed at least of Gd and Co showing an in-plane magnetization state at room temperature and a transition to a perpendicular magnetization state at temperatures of not lower than a critical temperature; and a recording magnetic layer formed of a perpendicular magnetization film, the reproducing magnetic layer and the recording magnetic layer being magneto-statically coupled at least in the vicinity of the critical temperature, the reproducing magnetic layer containing at least either Tb or Dy so as to increase the total magnetization at a temperature at which a perpendicular magnetic anisotropy constant and a diamagnetic field energy are equal to each other.Type: GrantFiled: June 29, 2000Date of Patent: March 18, 2003Assignee: Sharp Kabushiki KaishaInventors: Junji Hirokane, Noboru Iwata
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Patent number: 6532196Abstract: In a magneto-optical recording medium comprising a recording layer and a reproducing layer, a transfer layer and a magnetic shielding layer are successively formed between the recording layer and the reproducing layer respectively. The reproducing layer is prepared from Gd33(Fe70Co30)67 changing from an in-plane magnetization film to a perpendicular magnetization film at 150° C., for example. The transfer layer is prepared from Gd28(Fe90Co10)72 changing from an in-plane magnetization film to a perpendicular magnetization film at 50° C., for example. The magnetic shielding layer is prepared from SiN, for example. The recording layer is prepared from Tb20(Fe90Co10)80 whose saturation magnetization is maximized around the transition temperature of 50° C. of the transfer layer. A signal can be directly recorded in the recording layer with no magnetic influence from the reproducing layer.Type: GrantFiled: January 9, 2002Date of Patent: March 11, 2003Assignee: Sanyo Electric Co., Ltd.Inventors: Kenji Tanase, Yoshihisa Suzuki
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Patent number: 6521357Abstract: A magneto-optical recording medium including a recording layer for recording information and a substrate for supporting the recording layer is disclosed. The recording layer includes: a recording magnetic film for recording the information, the recording magnetic film being formed of a perpendicular magnetic anisotropy film; a readout magnetic film for optically reading out the information, the readout magnetic film being capable of being magnetically coupled with the recording magnetic film by an exchange-coupling force; and a controlling magnetic film, provided between the recording magnetic film and the readout magnetic film, for controlling the exchange-coupling force. The controlling magnetic film has in-plane magnetic anisotropy at room temperature.Type: GrantFiled: July 10, 2000Date of Patent: February 18, 2003Assignee: Matsushita Electric Industrial Co,. Ltd.Inventors: Yoshihiko Kudoh, Yasumori Hino, Yuuichi Fukamachi, Masahiro Birukawa
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Publication number: 20030002397Abstract: A magneto-optical recording medium for recording and reproducing data through light irradiation on a magnetic film side of the medium, the medium including at least one magnetic film which is formed on a substrate and has an easy axis of magnetization in a perpendicular direction and an in-plane magnetic film which is formed between the substrate and the magnetic film and has an easy axis of magnetization in an in-plane direction.Type: ApplicationFiled: September 25, 2001Publication date: January 2, 2003Applicant: FUJITSU LIMITEDInventor: Tsutomu Tanaka
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Publication number: 20020141293Abstract: A magneto-optical storage medium that protects against the effects of cross-talk, making it possible to further reduce the level of track density, and which also makes it possible to conduct high-density recording/playback with a reduced magnetic field for erasure and a favorable level of playback signal quality. More specifically, a magneto-optical storage medium, which includes at least the following laminated layers, in the following order: a playback layer, a non-magnetic layer, a transfer layer, a cut-off layer, and a recording layer. The playback layer preferably displays easy in-plane magnetization characteristics within the monolayer at room temperature, and the transfer layer and the recording layer each have easy magnetization characteristics in the vertical direction of the monolayers at room temperature when each layer is considered as a monolayer.Type: ApplicationFiled: March 22, 2002Publication date: October 3, 2002Applicant: Fujitsu LimitedInventor: Tetsuo Hosokawa
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Patent number: 6456571Abstract: A magneto-optical recording medium comprising a recording magnetic layer made of a perpendicularly magnetized film and a multilayer reproducing film, wherein the multilayer reproducing film has two reproducing magnetic layers which are in a in-plane magnetized state at room temperature and shift to a perpendicularly magnetized state with a rise in temperature and an in-panel magnetized layer disposed between the two reproducing magnetic layers, which is in an in-plane magnetized state from room temperature to a Curie temperature and has a lower Curie temperature than the recording magnetic layer and the reproducing magnetic layers.Type: GrantFiled: March 31, 2000Date of Patent: September 24, 2002Assignee: Sharp Kabushiki KaishaInventors: Junji Hirokane, Noboru Iwata
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Patent number: 6430115Abstract: A reproducing layer having perpendicular magnetization in a single layer, an in-plane magnetic layer, and a recording layer having perpendicular magnetization are formed in this order. When the reproducing layer, the in-plane magnetic layer, and the recording layer have the Curie temperatures of Tc1, Tc2, and Tc3, these values satisfy conditions of Tc2<Tc1 and Tc2<Tc3. The reproducing layer has in-plane magnetization due to an exchange coupling with the in-plane magnetic layer at lower than Tc2. At Tc2 or higher, magnetization information is expanded and transferred from the recording layer to the reproducing layer, so that the reproducing layer has single-domain perpendicular magnetization.Type: GrantFiled: August 31, 1999Date of Patent: August 6, 2002Assignee: Sharp Kabushiki KaishaInventors: Junji Hirokane, Noboru Iwata
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Patent number: 6400656Abstract: In a magneto-optical recording medium comprising a recording layer and a reproducing layer, a transfer layer and a magnetic shielding layer are successively formed between the recording layer and the reproducing layer respectively. The reproducing layer is prepared from Gd33(Fe70Co30)67 changing from an in-plane magnetization film to a perpendicular magnetization film at 150° C., for example. The transfer layer is prepared from Gd28(Fe90Co10)72 changing from an in-plane magnetization film to a perpendicular magnetization film at 50° C., for example. The magnetic shielding layer is prepared from SiN, for example. The recording layer is prepared from Tb20(Fe90Co10)80 whose saturation magnetization is maximized around the transition temperature of 50° C. of the transfer layer. A signal can be directly recorded in the recording layer with no magnetic influence from the reproducing layer.Type: GrantFiled: September 25, 1998Date of Patent: June 4, 2002Assignee: Sanyo Electric Co., Ltd.Inventors: Kenji Tanase, Yoshihisa Suzuki
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Patent number: 6388956Abstract: A magneto-optical storage medium includes an interference layer, a magnetic domain expansion layer, an intermediate layer, a magnetic masking layer, a recording layer, and a protection layer which are sequentially formed on a substrate. The magnetic domain expansion layer produces a smaller frictional force due to wall coercivity than do the other magnetic layers. The intermediate layer has the Curie temperature TC2 which is lower than those of the other magnetic layers. The magnetic masking layer is in a perpendicular magnetization state at temperatures that are in a proximity of TC2, and changes into an in-plane magnetization state at temperatures that are higher than the proximity of TC2. The recording layer produces a higher coercive force than those produced by the magnetic domain expansion layer at room temperature.Type: GrantFiled: November 16, 1999Date of Patent: May 14, 2002Assignee: Sharp Kabushiki KaishaInventors: Go Mori, Naoyasu Iketani, Michinobu Mieda, Akira Takahashi
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Patent number: RE38922Abstract: A magnetooptical recording medium has a first magnetic layer which is an in-plane magnetization film at both room temperature and high temperatures and changed to a perpendicular magnetization film at intermediate temperatures, and a second magnetic layer which is composed of a perpendicular magnetization film. The recording medium enables realization of high S/N reproduction of information recorded at a pitch below the diffraction limit of light with a simple structure, and further improvement in linear recording density and track density.Type: GrantFiled: November 3, 2000Date of Patent: December 20, 2005Assignee: Canon Kabushiki KaishaInventor: Naoki Nishimura