Patents by Inventor Soichi Oikawa

Soichi Oikawa 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).

  • Publication number: 20120275061
    Abstract: According to one embodiment, a magnetic recording device includes a magnetic recording head and a magnetic recording medium. The magnetic recording head includes a main magnetic pole, a shield and a stacked structure. The main magnetic pole has a medium facing surface and a main magnetic pole side surface. The shield has a shield side surface. The stacked structure is provided between the main magnetic pole and shield, and includes first and second magnetic layers, and an intermediate layer. The magnetic recording medium includes a backing layer and a magnetic recording layer. A distance between an end portion of the medium facing surface on a side of the stacked structure and the backing layer is twice or more of a distance between the main magnetic pole side surface and the shield side surface.
    Type: Application
    Filed: April 30, 2012
    Publication date: November 1, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masayuki TAKAGISHI, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Tomomi Funayama, Masahiro Takashita, Mariko Kitazaki, Soichi Oikawa
  • Publication number: 20120263975
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a substrate, and a multilayered magnetic recording layer formed on the substrate by alternately stacking two or more magnetic layers and two or more nonmagnetic layers. The magnetic layers and nonmagnetic layers of the multilayered magnetic recording layer are continuous layers. The magnetic layer includes a magnetic material portion, and a plurality of pinning sites dispersed in the magnetic material portion and made of a nonmagnetic metal different from a nonmagnetic material as a main component of the nonmagnetic layer. This perpendicular magnetic recording medium has magnetic characteristics by which a gradient a of a magnetization curve near the coercive force is 5 or more.
    Type: Application
    Filed: November 23, 2011
    Publication date: October 18, 2012
    Applicant: Kabushiki Kaisha Toshiba
    Inventor: Soichi OIKAWA
  • Patent number: 8238058
    Abstract: According to one embodiment, a magnetic recording head includes a main magnetic pole, a shield, and a stacked structure body. The shield is provided to oppose the main magnetic pole. The stacked structure body is provided between the main magnetic pole and the shield. The stacked structure body includes a first magnetic layer, a second magnetic layer, and an intermediate layer. The first magnetic layer has coercivity lower than a magnetic field applied from the main magnetic pole. A size of a film surface of the second magnetic layer is larger than a size of a film surface of the first magnetic layer. The intermediate layer is provided between the first magnetic layer and the second magnetic layer and is made of a nonmagnetic material. A current is configured to pass between the first magnetic layer and the second magnetic layer.
    Type: Grant
    Filed: February 7, 2011
    Date of Patent: August 7, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Mariko Shimizu, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
  • Publication number: 20120170151
    Abstract: According to one embodiment, a recording track has a surface modification layer in the surface region. This surface modification layer has an anisotropic magnetic field Hk reduced from that of a region between adjacent recording tracks.
    Type: Application
    Filed: March 14, 2012
    Publication date: July 5, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Soichi OIKAWA, Hitoshi IWASAKI, Masayuki TAKAGISHI, Kenichiro YAMADA, Tomomi FUNAYAMA, Masahiro TAKASHITA, Katsuhiko KOUI, Mariko SHIMIZU
  • Publication number: 20120154952
    Abstract: A magnetic recorder includes: a magnetic recording medium; a reproducing head; a magnetic recording head including: a main magnetic pole; a first magnetic layer containing a TM alloy; a second magnetic layer containing a TM alloy or an RE-TM alloy; a third magnetic layer containing an RE-TM alloy; a first intermediate layer provided between the first magnetic layer and the second magnetic layer; and a second intermediate layer provided between the second magnetic layer and the third magnetic layer; and a signal processing portion which performs signal writing into the magnetic recording medium by using the magnetic recording head and reading from the magnetic recording medium by using the reproducing head.
    Type: Application
    Filed: February 24, 2012
    Publication date: June 21, 2012
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Kenichiro YAMADA, Hitoshi IWASAKI, Masayuki TAKAGISHI, Tomomi FUNAYAMA, Masahiro TAKASHITA, Katsuhiko KOUI, Mariko KITAZAKI, Soichi OIKAWA
  • Publication number: 20120019960
    Abstract: According to one embodiment, a bit patterned medium includes a substrate, and a magnetic recording layer disposed above the substrate and including patterns of protrusions. Each of the protrusions contains a plurality of crystal grains. An average distance between the crystal grains is 0.5 to 3.0 nm in each of the protrusions. The protrusions include first protrusions each having a length of 1 ?m or more in a radial direction of the medium and second protrusions each having a length in the radial direction shorter than the length of the first protrusion in the radial direction. Each of the first protrusions has a nucleation field Hn for magnetization reversal and a coercive force Hc satisfying the inequalities, Hn?1.5 kOe and 0.5 kOe?Hc?Hn?1.5 kOe.
    Type: Application
    Filed: July 1, 2011
    Publication date: January 26, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi Sakurai, Yousuke Isowaki, Soichi Oikawa
  • Publication number: 20120002325
    Abstract: According to one embodiment, a magnetic recording head includes a main magnetic pole generating a recording magnetic field in a magnetic recording medium, a return yoke paired with the main magnetic pole, and a spin torque oscillator interposed between the main magnetic pole and the return yoke and including a spin injection layer, an oscillation layer, a nonmagnetic metal layer, and spin assist layer stacked in this order, wherein the nonmagnetic metal layer includes at least one metal selected from the group consisting of Cu, Au, Ag, Al, Pd, Pt, Os, and Ir, and the spin assist layer is a soft magnetic layer whose saturation magnetic flux density (Bs), diamagnetic field coefficient (N) and gap magnetic field (Hg) show a relationship expressed by Bs×N>Hg.
    Type: Application
    Filed: June 28, 2011
    Publication date: January 5, 2012
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Soichi OIKAWA, Katsuhiko Koui
  • Publication number: 20120002331
    Abstract: According to one embodiment, there is provided a magnetic recording head including a main pole, and a spin torque oscillator provided adjacent to the main pole and includes an oscillation layer including a first magnetic layer and a second magnetic layer and a third magnetic layer provided closer to the second magnetic layer and configured to inject a spin into the oscillation layer. The first magnetic layer has a saturation flux density of 1 T or more and 1.9 T or less.
    Type: Application
    Filed: June 28, 2011
    Publication date: January 5, 2012
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Soichi OIKAWA, Kenichiro YAMADA, Katsuhiko KOUI, Masayuki TAKAGISHI
  • Patent number: 8081397
    Abstract: A magnetic head assembly includes a magnetic recording head, a main magnetic pole, a head slider, a suspension and an actuator arm. The magnetic recording head includes a main magnetic pole having an air bearing surface facing a magnetic recording medium; and a stacked structure having, a first magnetic layer, a second magnetic layer, and an intermediate layer provided between the first magnetic layer and the second magnetic layer. A stacked plane of the stacked structure is inclined with respect to the air bearing surface. The magnetic recording head is mounted on the head slider. The head slider is mounted on one end of the suspension. The actuator arm is connected to the other end of the suspension.
    Type: Grant
    Filed: June 18, 2009
    Date of Patent: December 20, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomomi Funayama, Kenichiro Yamada, Katsuhiko Koui, Hitoshi Iwasaki, Masayuki Takagishi, Masahiro Takashita, Mariko Shimizu, Soichi Oikawa
  • Patent number: 8064244
    Abstract: A spin valve structure for a spintronic device is disclosed and includes a composite seed layer made of at least Ta and a metal layer having a fcc(111) or hcp(001) texture to enhance perpendicular magnetic anisotropy (PMA) in an overlying (Co/Ni)x multilayer. The (Co/Ni)x multilayer is deposited by a low power and high Ar pressure process to avoid damaging Co/Ni interfaces and thereby preserving PMA. As a result, only a thin seed layer is required. PMA is maintained even after annealing at 220° C. for 10 hours. Examples of GMR and TMR spin valves are described and may be incorporated in spin transfer oscillators and spin transfer MRAMs. The free layer is preferably made of a FeCo alloy including at least one of Al, Ge, Si, Ga, B, C, Se, Sn, or a Heusler alloy, or a half Heusler alloy to provide high spin polarization and a low magnetic damping coefficient.
    Type: Grant
    Filed: June 19, 2009
    Date of Patent: November 22, 2011
    Assignees: TDK Corporation, Kabushiki Kaisha Toshiba
    Inventors: Kunliang Zhang, Min Li, Yuchen Zhou, Soichi Oikawa, Kenichiro Yamada, Katsuhiko Koui
  • Publication number: 20110228423
    Abstract: A magnetic recording head includes a first ferromagnetic layer, an intermediate layer, a third ferromagnetic layer, a first magnetic pole and a second magnetic pole. The intermediate layer is provided between the first ferromagnetic layer and the second ferromagnetic layer. The third ferromagnetic layer includes a CoIr alloy and is provided so that the first ferromagnetic layer is sandwiched between the third ferromagnetic layer and the intermediate layer. The first magnetic pole is provided so that the third ferromagnetic layer is sandwiched between the first magnetic pole and the first ferromagnetic layer. The second magnetic pole is provided so that the second ferromagnetic layer is sandwiched between the second magnetic pole and the intermediate layer.
    Type: Application
    Filed: September 13, 2010
    Publication date: September 22, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Katsuhiko Koui, Kenichiro Yamada, Mariko Kitazaki, Hitoshi Iwasaki, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
  • Publication number: 20110205667
    Abstract: A magnetic recording head includes a magnetic pole, a spin torque oscillator, a first shield and a second shield. The magnetic pole has an air-bearing surface. The spin torque oscillator is provided so that a first side of the spin torque oscillator faces the magnetic pole in a first direction parallel to the air-bearing surface. The first shield includes a granular magnetic material, and is provided so that two portions of the first shield sandwich the spin torque oscillator in a second direction which is parallel to the air-bearing surface and perpendicular to the first direction. The second shield is provided on a second side of the spin torque oscillator opposite to the first side.
    Type: Application
    Filed: August 10, 2010
    Publication date: August 25, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Kenichiro YAMADA, Katsuhiko KOUI, Mariko KITAZAKI, Masayuki TAKAGISHI, Tomomi FUNAYAMA, Masahiro TAKASHITA, Soichi OIKAWA, Akihiko TAKEO
  • Publication number: 20110205655
    Abstract: According to one embodiment, a magnetic recording head includes a main magnetic pole, a shield, and a stacked structure body. The shield is provided to oppose the main magnetic pole. The stacked structure body is provided between the main magnetic pole and the shield. The stacked structure body includes a first magnetic layer, a second magnetic layer, and an intermediate layer. The first magnetic layer has coercivity lower than a magnetic field applied from the main magnetic pole. A size of a film surface of the second magnetic layer is larger than a size of a film surface of the first magnetic layer. The intermediate layer is provided between the first magnetic layer and the second magnetic layer and is made of a nonmagnetic material. A current is configured to pass between the first magnetic layer and the second magnetic layer.
    Type: Application
    Filed: February 7, 2011
    Publication date: August 25, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Mariko Shimizu, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
  • Patent number: 7901803
    Abstract: A perpendicular magnetic recording medium includes: a substrate; at least one underlayer formed above the substrate; and a perpendicular magnetic recording layer formed above the at least one underlayer, an easy magnetization axis of the perpendicular magnetic recording layer being oriented perpendicular to the substrate, the perpendicular magnetic recording layer including magnetic crystal particles and grain boundaries surrounding the magnetic crystal particles, wherein the grain boundaries contain an oxide of silicon and at least one element selected from the group consisting of Li, Na, K, Rb, Cs, Ca, Sr, and Ba, and the ratio of a total amount of substance of Si, Li, Na, K, Rb, Cs, Ca, Sr, and Ba in the perpendicular magnetic recording layer is no less than 1 mol % and no more than 20 mol %.
    Type: Grant
    Filed: October 5, 2004
    Date of Patent: March 8, 2011
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Tomoyuki Maeda, Soichi Oikawa, Takeshi Iwasaki, Futoshi Nakamura, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Patent number: 7901801
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a substrate, and a first magnetic layer and a second magnetic layer formed on the substrate, in which supposing that, for the first and second magnetic layers, respectively, uniaxial magnetic anisotropy constants are Ku1 and Ku2, saturation magnetizations are Ms1 and Ms2, anisotropic magnetic fields are Hk1 and Hk2 and the thicknesses are t1 and t2, then following conditions are satisfied that Ku1 and Ku2 are 3×106 erg/cc or more, Ms1 is smaller than Ms2, Hk1 is larger than Hk2 and t1 is larger than t2.
    Type: Grant
    Filed: July 2, 2008
    Date of Patent: March 8, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Soichi Oikawa, Tomoyuki Maeda
  • Patent number: 7867638
    Abstract: A magnetic-recording medium which is provided on a nonmagnetic substrate with at least an orientation-controlling layer for controlling the orientation of a layer formed directly thereon, a perpendicularly magnetic layer having an easily magnetizing axis oriented mainly perpendicularly relative to the nonmagnetic substrate, and a protective layer. The perpendicularly magnetic layer includes two or more magnetic layers, at least one of the magnetic layers is a layer having Co as a main component and containing Pt as well and containing an oxide, and at least another of the magnetic layers is a layer having Co as a main component and containing Cr as well and containing no oxide.
    Type: Grant
    Filed: November 20, 2008
    Date of Patent: January 11, 2011
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Akira Sakawaki, Kenji Shimizu, Kazuo Kobayashi, Hiroshi Sakai, Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Futoshi Nakamura
  • Patent number: 7781081
    Abstract: A magnetic recording medium 62 wherein a substrate 11, undercoating layers 13 and 14 formed on the substrate 11, and a magnetic recording layer 15, which include the magnetic crystal grain and the grain boundary field which encloses magnetic crystal grains, are included. The grain boundary field includes Ti oxide, and the ratio of the substance amount of the Ti oxide in the magnetic recording layer 15 is 5 mol % or more and 15 mol % or less, and the Ti oxide includes at least TiO and/or Ti2O3s.
    Type: Grant
    Filed: December 24, 2004
    Date of Patent: August 24, 2010
    Assignees: Showa Denko K.K., Kabushiki Kaisha Toshiba
    Inventors: Tomoyuki Maeda, Soichi Oikawa, Takeshi Iwasaki, Futoshi Nakamura, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
  • Publication number: 20100142088
    Abstract: A spin torque oscillator includes an amorphous soft magnetic layer, a nonmagnetic layer and a hard magnetic layer. The nonmagnetic layer with a close-packed crystal structure is provided on the amorphous soft magnetic layer. The hard magnetic layer with a close-packed crystal structure and perpendicular magnetic anisotropy is provided on the nonmagnetic layer.
    Type: Application
    Filed: October 6, 2009
    Publication date: June 10, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Hitoshi Iwasaki, Soichi Oikawa, Katsuhiko Koui, Kenichiro Yamada
  • Patent number: 7695832
    Abstract: In a perpendicular magnetic recording medium, a multilayered underlayer including a first metal underlayer, a second metal underlayer having no solid solution properties with respect to the first metal underlayer and having a hole, and a third metal underlayer having solid solution properties with respect to the first metal underlayer and having no solid solution properties with respect to the second metal underlayer is formed on a substrate, and a magnetic recording layer is formed on the multilayered underlayer.
    Type: Grant
    Filed: May 26, 2006
    Date of Patent: April 13, 2010
    Assignee: Kanushiki Kaisha Toshiba
    Inventor: Soichi Oikawa
  • Publication number: 20100073806
    Abstract: It is made possible to improve the recording resolution. A magnetic recording head includes: a magnetic pole that has a first magnetic portion including an air bearing surface, and generates a write magnetic field; and a spin torque oscillator that is formed on the air bearing surface of the magnetic pole, and is formed with a stack structure including a first magnetic layer, a second magnetic layer, and a nonmagnetic layer interposed between the first magnetic layer and the second magnetic layer, the second magnetic layer generating a high-frequency magnetic field when current is applied between the first magnetic layer and the second magnetic layer.
    Type: Application
    Filed: September 15, 2009
    Publication date: March 25, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Katsuhiko Koui, Hitoshi Iwasaki, Masayuki Takagishi, Kenichiro Yamada, Tomomi Funayama, Masahiro Takashita, Mariko Shimizu, Soichi Oikawa