Patents by Inventor Takuya Uzumaki

Takuya Uzumaki has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7402348
    Abstract: A magnetic recording layer is formed on an auxiliary magnetic layer in a perpendicular magnetic recording medium. The auxiliary magnetic layer has the axis of easy magnetization in the vertical direction perpendicular to the surface of a substrate. The perpendicular magnetic recording medium reliably allows establishment of the magnetization in the auxiliary magnetic layer in the vertical direction. When a magnetic flux flows along the vertical direction perpendicular to the surface of the magnetic recording layer, the magnetic flux flows across the magnetic recording layer in the vertical direction. The magnetization is thus reliably established in the magnetic recording layer in the vertical direction. The magnetic field of a stronger intensity is thus leaked out of the magnetic recording layer in the vertical direction.
    Type: Grant
    Filed: March 23, 2005
    Date of Patent: July 22, 2008
    Assignee: Fujitsu Limited
    Inventors: Hiroto Takeshita, Maki Maeda, Takuya Uzumaki
  • Publication number: 20070268632
    Abstract: A CPP-type magnetoresistive element including a fixed magnetization layer, a non-magnetic metal layer, and a free magnetization layer that are stacked, and a diffusion prevention layer is disclosed. The free magnetization layer includes CoMnAl. The diffusion prevention layer is provided between the non-magnetic metal layer and the free magnetization layer so as to prevent Mn included in the free magnetization layer from diffusing into the non-magnetic metal layer. CoMnAl has a composition within the area formed by connecting Point A (44, 23, 33), Point B (48, 25, 27), Point C (60, 20, 20), Point D (65, 15, 20), Point E (65, 10, 25), Point F (60, 10, 30), and Point A with straight lines in this order in a ternary composition diagram where coordinates of the composition are expressed as (Co content, Mn content, Al content) with each of the Co, Mn, and Al contents being expressed in atomic percentage.
    Type: Application
    Filed: April 25, 2006
    Publication date: November 22, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Arata Jogo, Hirotaka Oshima, Takahiro Ibusuki, Yutaka Shimizu, Takuya Uzumaki
  • Patent number: 7295404
    Abstract: A perpendicular magnetic recording medium at least comprises a perpendicular magnetic recording layer and a backing layer backing the perpendicular magnetic recording layer. The backing layer has an in-plane magnetization and is formed of a ferrimagnetic material having a compensation temperature in the vicinity of a recording/reproducing temperature in which reproducing of magnetic information is made from the perpendicular magnetic recording layer. A magnetic storage apparatus for recording and reproducing magnetic information using the perpendicular magnetic recording medium is also disclosed.
    Type: Grant
    Filed: January 30, 2007
    Date of Patent: November 13, 2007
    Assignee: Fujitsu Limited
    Inventors: Ryosaku Inamura, Kazumasa Shimoda, Toshio Sugimoto, Takuya Uzumaki
  • Patent number: 7258893
    Abstract: A method of fabricating a magnetic recording medium is disclosed, including a monomolecular film formation step of forming a monomolecular film on a substrate and a magnetic film formation step of forming on the monomolecular film a magnetic film for recording magnetic information. In the monomolecular film formation step, it is preferable to form a perylene-based organic monomolecular film.
    Type: Grant
    Filed: November 7, 2003
    Date of Patent: August 21, 2007
    Assignee: Fujitsu Limited
    Inventors: Hiroto Takeshita, Takuya Uzumaki
  • Publication number: 20070190365
    Abstract: The present invention provides a novel discrete track medium having a high magnetic recording density and manufacturing method therefor. This magnetic recording medium is a disk-shaped magnetic recording medium comprising a soft magnetic layer, a magnetic layer thereover, and an intermediate layer directly under the magnetic recording layer, wherein the magnetic recording layer comprises a plurality of magnetic recording tracks arranged in the radial direction of the magnetic recording medium, and each magnetic recording track is separated from the other in the radial direction of the disk by concave sections and convex sections formed alternately on the upper surface of the intermediate layer in the radial direction of the disk.
    Type: Application
    Filed: May 26, 2006
    Publication date: August 16, 2007
    Applicant: FUJITSU LIMITED
    Inventors: Hiroyoshi Kodama, Wataru Yamagishi, Takuya Uzumaki, Atsushi Tanaka
  • Publication number: 20070124749
    Abstract: A perpendicular magnetic recording medium at least comprises a perpendicular magnetic recording layer and a backing layer backing the perpendicular magnetic recording layer. The backing layer has an in-plane magnetization and is formed of a ferrimagnetic material having a compensation temperature in the vicinity of a recording/reproducing temperature in which reproducing of magnetic information is made from the perpendicular magnetic recording layer. A magnetic storage apparatus for recording and reproducing magnetic information using the perpendicular magnetic recording medium is also disclosed.
    Type: Application
    Filed: January 30, 2007
    Publication date: May 31, 2007
    Inventors: Ryosaku Inamura, Kazumasa Shimoda, Toshio Sugimoto, Takuya Uzumaki
  • Patent number: 7147940
    Abstract: The present invention provides a perpendicular magnetic recording medium that reduces medium noise and achieves thermal stability of recording magnetization. This perpendicular magnetic recording medium has a substrate and a recording layer formed by single-layered magnetic nanoparticles that are aligned at uniform intervals. An auxiliary magnetic film that is thinner than the recording layer is interposed between the substrate and the recording layer. The magnetization of the magnetic nanoparticles is secured by the exchange interaction effect of the auxiliary magnetic film.
    Type: Grant
    Filed: January 17, 2003
    Date of Patent: December 12, 2006
    Assignee: Fujitsu Limited
    Inventors: Maki Maeda, Hiroto Takeshita, Takuya Uzumaki
  • Publication number: 20060222900
    Abstract: A magnetic recording medium includes; a base member; an underlayer formed on the base member; a main recording layer formed on the underlayer, and a writing assist layer formed on or under the main recording layer in contact with the main recording layer. The main recording layer has perpendicular magnetic anisotropy with an anisotropic magnetic field of Hk1 and an inclination of a reversal part of a magnetization curve of a1. The writing assist layer has an anisotropic magnetic field of Hk2 and an inclination of a reversal part of a magnetization curve of a2. The anisotropic magnetic fields Hk1 and Hk2 and the inclinations a1 and a2 satisfy Hk1>Hk2 ?0 and a1>a2.
    Type: Application
    Filed: June 28, 2005
    Publication date: October 5, 2006
    Applicant: FUJITSU LIMITED
    Inventors: Ryosaku Inamura, Isatake Kaitsu, Takuya Uzumaki
  • Publication number: 20060222901
    Abstract: A magnetic recording medium includes; a base member; an underlayer formed on the base member; a main recording layer formed on the underlayer, and a writing assist layer formed on or under the main recording layer in contact with the main recording layer. The main recording layer has perpendicular magnetic anisotropy with an anisotropic magnetic field of Hk1 and an inclination of a reversal part of a magnetization curve of a1. The writing assist layer has an anisotropic magnetic field of Hk2 and an inclination of a reversal part of a magnetization curve of a2. The anisotropic magnetic fields Hk1 and Hk2 and the inclinations a1 and a2 satisfy Hk1>Hk2 and a2>a1.
    Type: Application
    Filed: March 14, 2006
    Publication date: October 5, 2006
    Applicant: FUJITSU LIMITED
    Inventors: Ryosaku Inamura, Isatake Kaitsu, Takuya Uzumaki
  • Publication number: 20060134468
    Abstract: A soft magnetic thin film in which the recording magnetic field in the perpendicular direction can be preferentially intensified and sharply controlled when the thin film is applied to a perpendicular magnetic recording medium is provided. This soft magnetic thin film can be obtained by immersing a substrate into an electroless plating bath that contains a Co ion, Fe ion, and Ni ion as metal ions, as well as a complexing agent and a boron-type reducing agent, wherein the content ratios of the metal ions on the mole basis are 0.15?(Ni ion amount/the amount of total metal ions) ?0.40, 0.50?(Co ion amount/the amount of total metal ions) ?0.80, and 0.05?(Fe ion amount/the amount of total metal ions) ?0.15; and carrying out electroless plating in a magnetic field in a range of 5-2,000 Oe given in a direction parallel to the surface of said substrate.
    Type: Application
    Filed: March 18, 2005
    Publication date: June 22, 2006
    Inventors: Sanae Shimizu, Daiju Kaneko, Takuya Uzumaki, Atsushi Tanaka
  • Patent number: 7008705
    Abstract: A layered polycrystalline structure includes a seed crystal or Cr layer containing non-magnetic Cr atoms. A non-magnetic crystal layer such as a Co65Cr35 layer is formed on the exposed surface of the seed crystal layer. A magnetic crystal layer such as a co88Pt12 layer is formed on the exposed surface of the non-magnetic crystal layer. Heat treatment induces the diffusion of the Cr atoms along the grain boundaries within the magnetic crystal layer. Walls of a non-magnetic material can be established along the grain boundaries in the magnetic crystal layer. The diffusion of the Cr atoms can sufficiently be suppressed within the lattices of the magnetic crystal grains. Generation of an incomplete non-magnetic region can thus be restrained to the utmost within the magnetic crystal layer. Noise can be reduced in reproduction of a magnetic information data.
    Type: Grant
    Filed: March 20, 2001
    Date of Patent: March 7, 2006
    Assignee: Fujitsu Limited
    Inventors: Ryoichi Mukai, Takuya Uzumaki
  • Publication number: 20050260340
    Abstract: The present invention aims to provide a magnetic recording medium improved in recording density, with maintaining various performances thereof, an efficient process for manufacturing the magnetic recording medium, and a nanoparticle for a magnetic recording medium sufficiently utilized therefor. The nanoparticle for a magnetic recording medium of the present invention has an organic compound capable of generating carbon adhering to the surface thereof, or 7 nm or less of a number average particle diameter thereof, or 0.1 or less of a particle distribution (distribution width (?)/particle diameter (D)) thereof. The magnetic recording medium of the present invention has a recording layer containing the nanoparticle for a magnetic recording medium. The process for manufacturing a magnetic recording medium of the present invention includes a step of applying, onto a substrate and in a magnetic field, a nanoparticle dispersed liquid in which the nanoparticle for a magnetic recording medium is dispersed.
    Type: Application
    Filed: June 17, 2005
    Publication date: November 24, 2005
    Applicant: Fujitsu Limited
    Inventors: Nobutaka Ihara, Hiroyoshi Kodama, Takuya Uzumaki
  • Publication number: 20050249982
    Abstract: A magnetic recording layer is formed on an auxiliary magnetic layer in a perpendicular magnetic recording medium. The auxiliary magnetic layer has the axis of easy magnetization in the vertical direction perpendicular to the surface of a substrate. The perpendicular magnetic recording medium reliably allows establishment of the magnetization in the auxiliary magnetic layer in the vertical direction. When a magnetic flux flows along the vertical direction perpendicular to the surface of the magnetic recording layer, the magnetic flux flows across the magnetic recording layer in the vertical direction. The magnetization is thus reliably established in the magnetic recording layer in the vertical direction. The magnetic field of a stronger intensity is thus leaked out of the magnetic recording layer in the vertical direction.
    Type: Application
    Filed: March 23, 2005
    Publication date: November 10, 2005
    Inventors: Hiroto Takeshita, Maki Maeda, Takuya Uzumaki
  • Publication number: 20050233178
    Abstract: A vertical magnetic recording medium comprises a substrate, a soft magnetic backing layer formed on the substrate, a magnetic flux confinement layer formed on the soft magnetic backing layer, an intermediate layer formed on the magnetic flux confinement layer, and a recording layer of a vertical magnetization film formed on the intermediate layer, wherein the magnetic flux confinement part comprises a plurality of soft magnetic parts each formed along a track region of plural track regions and a non-magnetic part formed between adjacent track regions, the intermediate layer being formed of a non-magnetic material and is formed so as to cover a surface of the soft magnetic part and the non-magnetic parts.
    Type: Application
    Filed: September 10, 2004
    Publication date: October 20, 2005
    Inventors: Toshio Sugimoto, Takuya Uzumaki, Atsushi Tanaka
  • Publication number: 20050196606
    Abstract: A substrate defines minute holes or nanoholes over its surface in a composite material. Particles or nanoparticles are filled within the minute holes. The composite material enables a reliable disposition of the particles within the minute holes. The position of the minute holes can reliably be controlled. This serves to establish regularly ordered particles based on the regularly ordered minute holes. This composite material is applicable to a magnetic recording medium.
    Type: Application
    Filed: March 28, 2005
    Publication date: September 8, 2005
    Inventors: Nobutaka Ihara, Takuya Uzumaki, Atsushi Tanaka, Satoru Momose, Hiroyoshi Kodama
  • Publication number: 20050196649
    Abstract: A perpendicular magnetic recording medium includes a magnetic orientation controller layer serving as a layer for controlling crystalline orientation in an upper layer. A non-magnetic orientation controller layer extends on the surface of the magnetic orientation controller layer The non-magnetic orientation controller layer serves as a layer for controlling crystalline orientation in an upper layer. A magnetic recording layer extends on the surface of the non-magnetic orientation controller layer. The perpendicular magnetic recording medium allows a reliable establishment of a uniform crystalline orientation in the magnetic recording layer based on the influences from the magnetic and non-magnetic orientation controller layers. A reliable establishment of a uniform crystalline orientation can be achieved without an increase in the thickness of the non-magnetic orientation controller layer.
    Type: Application
    Filed: March 28, 2005
    Publication date: September 8, 2005
    Inventors: Ryosaku Inamura, Hiroto Takeshita, Toshio Sugimoto, Kazumasa Shimoda, Takenori Oshima, Maki Maeda, Takuya Uzumaki, Atsushi Tanaka
  • Publication number: 20050123805
    Abstract: A perpendicular magnetic recording medium including a substrate, a metal base layer formed on the substrate, a soft magnetic layer formed on the metal base layer by electroless plating and having an axis of easy magnetization in the in-plane direction of the substrate, and a magnetic recording layer formed on the soft magnetic layer and having an axis of easy magnetization in a direction perpendicular to the surface of the substrate. The metal base layer is formed of an alloy containing at least one element selected from the group consisting of Co, Ni, and Fe, and has a coercivity of 3 oersteds (Oe) or less. The soft magnetic layer has a thickness of 100 to 600 nm.
    Type: Application
    Filed: January 13, 2005
    Publication date: June 9, 2005
    Inventors: Sanae Shimizu, Arata Jogo, Takuya Uzumaki, Atsushi Tanaka
  • Patent number: 6878439
    Abstract: A magnetic recording medium and a magnetic recording device using the same. The magnetic recording medium has a nonmagnetic substrate having applied thereon, through a crystal orientation-improving layer and a seed layer, a magnetic recording layer. The seed layer consists of a material having a higher surface energy than that of the crystal orientation-improving layer.
    Type: Grant
    Filed: February 6, 2002
    Date of Patent: April 12, 2005
    Assignee: Fujitsu Limited
    Inventors: Hiroyoshi Kodama, Nobutaka Ihara, Takuya Uzumaki
  • Patent number: 6875527
    Abstract: A perpendicular magnetic recording medium including a substrate, a soft-magnetic backing layer formed on the substrate, a magnetic recording layer having perpendicular magnetic anisotropy formed on the backing layer, and a leakage magnetic field control layer having ferrimagnetism formed on the magnetic recording layer. The leakage magnetic field control layer is exchange-coupled to the magnetic recording layer antiferromagnetically or ferrimagnetically to thereby suppress the influence of leakage magnetic fields from the backing layer and the magnetic recording layer and reduce the medium noise.
    Type: Grant
    Filed: December 11, 2002
    Date of Patent: April 5, 2005
    Assignee: Fujitsu Limited
    Inventors: Toshio Sugimoto, Takuya Uzumaki
  • Publication number: 20050042481
    Abstract: A perpendicular magnetic recording medium including a substrate, a roughness control layer provided on the substrate and having a rough surface with a grain size of 5 to 20 nm and an average roughness (Ra) of 0.2 to 2.0 nm, and an orientation control layer provided on the roughness control layer and containing 30 at % or more of metal solely having an fcc structure. The perpendicular magnetic recording medium further includes a magnetic recording layer having perpendicular magnetic anisotropy provided on the orientation control layer in contact therewith. The magnetic recording layer is formed from a multilayer film composed of ferromagnetic thin films and nonmagnetic thin films alternately stacked.
    Type: Application
    Filed: October 6, 2004
    Publication date: February 24, 2005
    Inventors: Kazumasa Shimoda, Takuya Uzumaki