By Transferring Magnetic Domain Between Layers Patents (Class 369/13.06)
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Patent number: 9001630Abstract: A perpendicular magnetic recording (PMR) disk used in energy assisted magnetic recording drives is described. The PMR disk includes a substrate, a magnetic recording layer disposed above the substrate, an exchange coupling layer disposed above the magnetic recording layer, and a capping layer disposed above the exchange coupling layer. The capping layer has a Curie temperature greater than the Curie temperature of the magnetic recording layer.Type: GrantFiled: April 24, 2014Date of Patent: April 7, 2015Assignee: Western Digital Technologies, Inc.Inventors: Gerardo A. Bertero, Michael Alex, Christopher B. Wolf, Eric J. Champion
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Patent number: 8743666Abstract: A perpendicular magnetic recording (PMR) disk used in energy assisted magnetic recording drives is described. The PMR disk includes a substrate, a magnetic recording layer disposed above the substrate, an exchange coupling layer disposed above the magnetic recording layer, and a capping layer disposed above the exchange coupling layer. The capping layer has a Curie temperature greater than the Curie temperature of the magnetic recording layer.Type: GrantFiled: March 8, 2011Date of Patent: June 3, 2014Assignee: Western Digital Technologies, Inc.Inventors: Gerardo A. Bertero, Michael Alex, Christopher B. Wolf, Eric J. Champion
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Patent number: 8724434Abstract: A magnetic recording system including follows: a recording head, a recording medium that includes a first recording medium layer, a second recording medium layer, and a substrate. The magnetic recording system includes an electric field applying device applying an electric field and a magnetic field applying device applying a magnetic field to the recording medium, a movement mechanism that moves them to an arbitrary position. The magnetic recording system has a function of controlling an applying direction of at least one of the electric field applying device and the magnetic field applying device, and the recording head is arranged at a position facing the recording medium.Type: GrantFiled: March 15, 2013Date of Patent: May 13, 2014Assignee: TDK CorporationInventors: Mikio Matsuzaki, Koichi Shinohara, Tatsuo Shibata, Masashi Sahashi, Tomohiro Nozaki
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Patent number: 7352658Abstract: A magnetic recording medium comprises a first magnetic film and a second magnetic film on a substrate. The second magnetic film is composed of a magnetic material preferred for recording and reproduction, and the first magnetic film is composed of a ferrimagnetic material excellent in thermal stability. Information is recorded in the second magnetic film by using a magnetic head. The first magnetic film is heated by being irradiated with a laser beam to lower coercivity, and the information in the second magnetic film is magnetically transferred to the first magnetic film. The recorded information is stabilized, because the first magnetic film is excellent in thermal stability. The magnetic recording medium is highly resistant to thermal fluctuation, and it has high reliability. A magnetic domain of about 0.1 ?m, formed by magnetic recording at a super high density of 50 Gb/inch2, is successfully and stably allowed to exist.Type: GrantFiled: February 7, 2001Date of Patent: April 1, 2008Assignee: Hitachi Maxell, Ltd.Inventors: Katsusuke Shimazaki, Norio Ohta, Fumiyoshi Kirino
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Patent number: 7352659Abstract: A method and apparatus for controlling read-out and/or synchronization between an external magnetic field and written data during a reading operation from a magneto-optical recording medium includes generating a pulse in a reading signal in a read-out layer by copying a mark region from a storage layer to the read-out layer upon heating by a radiation power and with the aid of the external magnetic field. The waveform of the reading signal is analyzed, and the analysis result is used for correcting a phase deviation and/or for controlling a copy window size of the mark copying. Phase errors may thus be corrected for any size of the copy window. Even small changes in the copy window can be detected and corrected.Type: GrantFiled: January 24, 2003Date of Patent: April 1, 2008Assignee: Koninklijke Philips Electronics N.V.Inventor: Coen Adrianus Verschuren
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Publication number: 20080068936Abstract: A method of data recording and reading for a memory device employing magnetic domain wall movement. The memory device includes a writing track, an interconnecting layer formed on the writing track, and a recording track formed on the interconnecting layer.Type: ApplicationFiled: May 18, 2007Publication date: March 20, 2008Applicant: SAMSUNG ELECTRONICS CO., LTDInventors: Chee-kheng LIM, Eun-sik KIM
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Patent number: 7233547Abstract: A magneto-optical disk which reproduces information with an optical pickup head which uses an electromagnetic force as the driving force is provided. Other areas than at least the recording track are magnetized uniformly in a direction of canceling the influence of external magnetic field applied by the optical pickup head or a recording pattern having a frequency higher than modulation transfer function (MTF) of the optical pickup head is recorded to the other areas than at least the recording track. Read signals SP12 and SP14 from the magneto-optical disk are low in bit error rate.Type: GrantFiled: June 6, 2003Date of Patent: June 19, 2007Assignee: Sony CorporationInventors: Yoshiyuki Teraoka, Makoto Watanabe
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Patent number: 7193934Abstract: The present invention is a method of reading and writing in MAMMOS that uses the edge of the thermal profile for detection of a domain rather than using the tip of the profile. By using the edge, it is possible to detect the position of domains rather than merely the presence of domains. Thus, domain positions are used to store data. By measuring these positions relative to the last domain, more accuracy can be gained. The new scheme is called Domain Position Detection for MAMMOS (DPD-MAMMOS). In DPD-MAMMOS, the information is encoded into the MAMMOS media in the form of the position of the domains rather than the presence of the domains. In this way, each domain stored in the media can contain several bits or possibly bytes of information. Methods of reading and writing information are disclosed.Type: GrantFiled: June 7, 2002Date of Patent: March 20, 2007Assignee: Carnegie Mellon UniversityInventor: Philipp Herget
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Patent number: 7126883Abstract: An optical information reproducing method of the present invention is used for an optical recording medium. The optical recording medium includes a recording layer containing information and a mask layer that is located close to the recording layer and includes a nonlinear optical material whose optical properties are changed in accordance with incident light intensity. The method includes irradiating the optical recording medium with convergent light that is polarized in a first direction and dividing reflected light from the optical recording medium into a first polarized component that is polarized in the first direction and a second polarized component that is polarized in a second direction perpendicular to the first direction. The second polarized component is used to detect a reproduction signal.Type: GrantFiled: October 9, 2002Date of Patent: October 24, 2006Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Hiroaki Yamamoto, Teruhiro Shiono
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Patent number: 6944100Abstract: A magneto-optical recording/reproducing method is disclosed which causes a laser beam to be emitted to a disc recording medium having information recorded thereon earlier by magnetic field modulation, the laser beam causing the disc recording medium to develop a temperature distribution such as to generate a driving force for moving a domain wall of a magnetic domain in the medium so that the magnetic domain smaller in diameter than a spot of the laser beam is expanded sufficiently to let information recorded in the domain be detected. The method comprises the steps of: recording information to the disc recording medium while rotating the medium in a first rotating direction; and reproducing the information that was recorded to the disc recording medium in the recording step while rotating the medium in a second rotating direction reverse to the first rotating direction.Type: GrantFiled: March 11, 2003Date of Patent: September 13, 2005Assignee: Sony CorporationInventors: Tetsuhiro Sakamoto, Yasuhito Tanaka, Kazuhiko Fujiie
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Patent number: 6868048Abstract: Embodiments of a data storage system having thermally activated readout are provided, in one embodiment, a data storage system includes a source of heat, a substrate, a write layer disposed above the substrate, a copy layer disposed above the write layer, a flying head disposed above the layers and carrying the source of heat for heating a selected spot on the copy and write layers, wherein the write layer comprises a ferromagnetic material selected to have an extremely high coercivity at room temperature and a very high write temperature Twrite, and the copy layer comprises a ferromagnetic material selected to have a coercivity always less than coercivity of the write layer at the same temperature and a copy temperature Tcopy substantially less than the write temperature of the write layer.Type: GrantFiled: February 5, 2001Date of Patent: March 15, 2005Assignee: Seagate Technology, LLCInventors: Terry McDaniel, Karl A. Belser, Edward C. Gage, Randall H. Victora, James E. Durnin, Charles F. Brucker
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Patent number: 6847590Abstract: A magneto-optical recording medium which includes a reproducing layer. When a laser beam is irradiated to the magneto-optical recording medium, a magnetic domain in a recording layer is transferred, through enlargement, to a reproducing layer increased in temperature. The magneto-optical recording medium further includes a calibration area that has a calibration magnetic domain recorded in a predetermined pattern in the recording layer. In a reproducing apparatus, a laser beam of an optical head is adjusted in output depending upon a reproduced signal obtained by reproducing the calibration magnetic domain.Type: GrantFiled: August 17, 2001Date of Patent: January 25, 2005Assignees: Sanyo Electric Co., Ltd., Hitachi Maxell, Ltd.Inventors: Atsushi Yamaguchi, Naoyuki Takagi, Yoshiharu Uchihara, Satoshi Sumi, Hiroyuki Awano, Hiroshi Shirai, Hitoshi Watanabe, Norio Ohta
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Publication number: 20040218476Abstract: An optical disk is made of tracks that are magnetically separated from one another by scanning a focused light beam over lands between tracks at a predetermined power and annealing to lower the magnetic anisotropy of a magnetic layer on the lands, and is provided with a power testing region comprising one or more tracks for finding the predetermined annealing power at the location of at least one of the group consisting of a specific region within the data region, a region more to the inner side than the innermost track of the data region, and a region more to the outer side than the outermost track of the data region. Thus, an optical disk and a manufacturing method for the same can be provided that have a high recording density and with which annealing can be implemented in a short time and at the correct annealing width.Type: ApplicationFiled: June 2, 2004Publication date: November 4, 2004Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD., CANON KABUSHIKI KAISHAInventors: Kenzo Ishibashi, Yasumori Hino, Yasuyuki Miyaoka, Hirotake Ando
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Publication number: 20040196743Abstract: A magneto-optical disk which reproduces information with an optical pickup head which uses an electromagnetic force as the driving force is provided. Other areas than at least the recording track are magnetized uniformly in a direction of canceling the influence of external magnetic field applied by the optical pickup head or a recording pattern having a frequency higher than modulation transfer function (MTF) of the optical pickup head is recorded to the other areas than at least the recording track. Read signals SP12 and SP14 from the magneto-optical disk are low in bit error rate.Type: ApplicationFiled: February 10, 2004Publication date: October 7, 2004Inventors: Yoshiyuki Teraoka, Makoto Watanabe
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Publication number: 20040160860Abstract: Recording/reproducing methods and apparatuses for a magneto-optical recording medium are disclosed. The magneto-optical recording medium may include a recording layer in which information can be recorded and a reproducing layer to which information in the recording layer can be transferred. According to one embodiment, the method includes encoding the data to be recorded/reproduced with a low-density parity check code, writing the encoded data to the recording layer of the magneto-optical recording medium, transferring the encoded data from the recording layer to the reproducing layer, and decoding the encoded data from the reproducing layer.Type: ApplicationFiled: February 18, 2003Publication date: August 19, 2004Inventors: Hongwei Song, Jingfeng Liu, Vijayakumar Bhagavatula, Akira Inaba, Katsusuke Shimazaki, Norio Ota
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Publication number: 20040160861Abstract: The present invention relates to a method and an apparatus for reading information from a domain expansion magneto-optical recording medium, wherein the duty cycle of an external magnetic field is set so that the duration of the expanded domain in the read-out layer is longer than the duration of the domain collapse direction. A smaller bandwidth of the detection system can thus be allowed and the signal-to-noise ratio is improved. Furthermore, an additional level may be introduced for the external magnetic field between the expansion direction and the collapse direction so as to obtain an as short as possible expansion and collapse pulse. An improved resolution and SNR can thus be obtained.Type: ApplicationFiled: December 9, 2003Publication date: August 19, 2004Inventors: Coen Adrianus Verschuren, Hans Willem Van Kesteren
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Publication number: 20040141425Abstract: In a DWDD (Domain Wall Displacement Detection) optical recording medium of a land and groove recording system, characteristics of a land and a groove can be well equilibrated by selecting a depth d (nm) of a groove 3 of an optical recording medium so as to satisfy the following equation:Type: ApplicationFiled: October 23, 2003Publication date: July 22, 2004Inventors: Goro Fujita, Tetsuhiro Sakamoto
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Patent number: 6690624Abstract: A magnetic lens has a reproducing layer and a magnetic slit. When the leak magnetic field Hlk of a recording magnetic domain on a recording disk exceeds the coercive force He of the magnetic slit, the magnetization in the magnetic slit is inverted into the same direction as that of the magnetization of the recording magnetic domain. Transition occurs from the in-plane magnetization to the perpendicular magnetization in a magnified area of the reproducing layer in which the temperature exceeds the critical temperature Tcr. The upward magnetization in the magnetic slit is transferred thereto. The magnetization information on the recording magnetic domain is reproduced with amplified signal intensity on the basis of the magneto-optical effect by detecting the reflected light beam of the reproducing light beam from the magnified area. A plurality of minute magnetic domains contained in an object can be detected respectively at a high sensitivity in an independent manner.Type: GrantFiled: July 3, 2002Date of Patent: February 10, 2004Assignee: Hitachi Maxell, Ltd.Inventors: Katsusuke Shimazaki, Yoshitane Tsuburaya
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Patent number: 6665235Abstract: Featured is a recording and reproducing method of a magneto-optical recording medium including a recording layer for recording thereon information magneto-optically and a readout layer which has in-plane magnetization at room temperature and where a transition occurs from in-plane magnetization to perpendicular magnetization as temperature raises. The method includes projecting a light beam onto such a magneto-optical recording medium so as to form a perpendicularly magnetized area in the readout layer by duplication of the magnetization of said recording layer to the area. In further embodiments, the recording medium further includes an intermediate layer made of non-magnetic film formed between the readout and recording layers and the readout and recording layers are composed of rare-earth transition metal alloys such as TbFeCo (recoding layer) readout layer, made of GdFeCo (readout layer).Type: GrantFiled: August 8, 2002Date of Patent: December 16, 2003Assignee: Sharp Kabushiki KaishaInventors: Yoshiteru Murakami, Junji Hirokane, Junichiro Nakayama, Junsaku Nakajima, Akira Takahashi, Kenji Ohta, Naoyasu Iketani
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Publication number: 20030214886Abstract: A magneto-optical recording/reproducing method is disclosed which causes a laser beam to be emitted to a disc recording medium having information recorded thereon earlier by magnetic field modulation, the laser beam causing the disc recording medium to develop a temperature distribution such as to generate a driving force for moving a domain wall of a magnetic domain in the medium so that the magnetic domain smaller in diameter than a spot of the laser beam is expanded sufficiently to let information recorded in the domain be detected. The method comprises the steps of: recording information to the disc recording medium while rotating the medium in a first rotating direction; and reproducing the information that was recorded to the disc recording medium in the recording step while rotating the medium in a second rotating direction reverse to the first rotating direction.Type: ApplicationFiled: March 11, 2003Publication date: November 20, 2003Applicant: Sony CorporationInventors: Tetsuhiro Sakamoto, Yasuhito Tanaka, Kazuhiko Fujiie
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Publication number: 20030179658Abstract: A magnetic recording medium 10 comprises a first magnetic film 2 and a second magnetic film 4 on a substrate 1. The first magnetic film is composed of a magnetic material preferred for recording and reproduction, and the second magnetic film is composed of a ferrimagnetic material excellent in thermal stability. Information is recorded in the second magnetic film by using a magnetic head 53. After recording the information in the second magnetic film, the first magnetic film is heated by being irradiated with a laser beam to lower the coercivity, and the information in the second magnetic film is magnetically transferred to the first magnetic film. The recorded information is stabilized, because the first magnetic film is excellent in thermal stability. The magnetic recording medium as described above is highly resistant to thermal fluctuation, and it has high reliability. In particular, a magnetic domain of about 0.Type: ApplicationFiled: March 25, 2003Publication date: September 25, 2003Inventors: Katsusuke Shimazaki, Norio Ohta, Fumiyoshi Kirino
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Patent number: 6572957Abstract: A magneto-optical recording medium incorporates a recording layer constituted by a multi-layered magnetic film composed of at least three magnetic layers. Domain walls of the magnetic layer adjacent to the portion irradiated with reproducing light are moved toward the center of the spot in a forward portion in a direction, in which the reproducing light spot is moved, so that a recording magnetic domain is enlarged, and movement of the domain walls of the magnetic layer adjacent to the portion irradiated with reproducing light is inhibited in a rear portion in the direction in which the reproducing light spot is moved. To inhibit movement of the domain walls of the magnetic layer adjacent to the portion irradiated with reproducing light, insertion of a magnetic layer having a predetermined magnetic characteristic into a space between a displacement layer and a switch layer is required.Type: GrantFiled: March 23, 2001Date of Patent: June 3, 2003Assignee: Sony CorporationInventor: Katsuhisa Aratani
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Publication number: 20030026173Abstract: A method of reading out data from a domain expansion data storage such as a MAMMOS magneto-optic disk (1) which includes a data storage layer in which data is stored in the form of magnetic marks, and an expansion layer capable of copying and expanding domains from the storage layer, the system applying a first radiation beam (7), having a first spot size on the disk, in order to initiate copying of a domain from the storage layer to the expansion layer, and applying a second radiation beam (9), having a second spot size larger than the first spot size on the disk, in order to read out data from the expansion layer.Type: ApplicationFiled: July 30, 2002Publication date: February 6, 2003Inventor: Coen Adrianus Verschuren
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Patent number: 6421304Abstract: A magneto-optical reproducing apparatus for reproducing from a magnetic film medium having at least a displacement layer, a switching layer, and a memory layer. A magnetic wall displacement is generated in the displacement layer in any region where the temperature exceeds the Curie temperature of the switching layer to effectively enlarge any recorded magnetic domain. The reproduced signal from the magnetic film medium is equalized with regard to waveform in an equalizer circuit and then fed to a magnetic wall displacement detection circuit that produces a magnetic wall displacement signal by using a differential signal or a secondary differential signal of the reproduced signal so as to provide a low bit error rate despite any sudden DC level variation in the reproduced signal.Type: GrantFiled: April 18, 2000Date of Patent: July 16, 2002Assignee: Sony CorporationInventors: Shunji Yoshimura, Atsushi Fukumoto, Shinichi Kai
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Publication number: 20020027835Abstract: A reproducing apparatus reproduces a signal recorded in a magneto-optical disk. The magneto-optical disk includes a layered structure having a recording layer, an intermediate layer and a reproducing layer. Laser light is illuminated from an optical head to the magneto-optical disk in such an intensity that no magnetic domain is transferred from the recording layer to the reproducing layer only by the laser light. In this state, alternating magnetic field is applied through a magnetic head to the magneto-optical disk, thereby concurrently causing transfer and expansion of a magnetic domain to the reproducing layer. As a result, transfer of the magnetic domain is effected with expansion.Type: ApplicationFiled: August 7, 2001Publication date: March 7, 2002Applicant: SANYO ELECTRIC COMPANY, LTDInventors: Naoyuki Takagi, Atsushi Yamaguchi, Kenichiro Mitani
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Publication number: 20010040841Abstract: A recording method including a read/write optical assembly combining near-field optical writing and magnetic flux reading is invented. The multi-layer structure and properties of media suitable for this recording method is disclosed. Near-field optical writing (such as solid immersion lens, SIL) with/without external magnetic field can shrink the size of the recorded spot substantially. The GMR (Giant Magneto-Resistive) or TMR (Tunneling Magneto-Resistive) device has the advantage of high-resolution for sensing magnetic flux. Taking advantage of both devices, a new high-density data recording system, which consists of near-field optical writing and magnetic flux detection, can be developed. Thus, areal recording density of the re-writable optical disk can be increased substantially.Type: ApplicationFiled: December 14, 2000Publication date: November 15, 2001Inventors: Han-Ping David Shieh, Po-Cheng Kuo, Wei-Chih Hsu