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).
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Publication number: 20120275061Abstract: 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: ApplicationFiled: April 30, 2012Publication date: November 1, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Masayuki TAKAGISHI, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Tomomi Funayama, Masahiro Takashita, Mariko Kitazaki, Soichi Oikawa
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Publication number: 20120263975Abstract: 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: ApplicationFiled: November 23, 2011Publication date: October 18, 2012Applicant: Kabushiki Kaisha ToshibaInventor: Soichi OIKAWA
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Patent number: 8238058Abstract: 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: GrantFiled: February 7, 2011Date of Patent: August 7, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Mariko Shimizu, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
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Publication number: 20120170151Abstract: 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: ApplicationFiled: March 14, 2012Publication date: July 5, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Soichi OIKAWA, Hitoshi IWASAKI, Masayuki TAKAGISHI, Kenichiro YAMADA, Tomomi FUNAYAMA, Masahiro TAKASHITA, Katsuhiko KOUI, Mariko SHIMIZU
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Publication number: 20120154952Abstract: 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: ApplicationFiled: February 24, 2012Publication date: June 21, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Kenichiro YAMADA, Hitoshi IWASAKI, Masayuki TAKAGISHI, Tomomi FUNAYAMA, Masahiro TAKASHITA, Katsuhiko KOUI, Mariko KITAZAKI, Soichi OIKAWA
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Publication number: 20120019960Abstract: 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: ApplicationFiled: July 1, 2011Publication date: January 26, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Masatoshi Sakurai, Yousuke Isowaki, Soichi Oikawa
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Publication number: 20120002325Abstract: 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: ApplicationFiled: June 28, 2011Publication date: January 5, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Soichi OIKAWA, Katsuhiko Koui
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Publication number: 20120002331Abstract: 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: ApplicationFiled: June 28, 2011Publication date: January 5, 2012Applicant: Kabushiki Kaisha ToshibaInventors: Soichi OIKAWA, Kenichiro YAMADA, Katsuhiko KOUI, Masayuki TAKAGISHI
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Patent number: 8081397Abstract: 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: GrantFiled: June 18, 2009Date of Patent: December 20, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Tomomi Funayama, Kenichiro Yamada, Katsuhiko Koui, Hitoshi Iwasaki, Masayuki Takagishi, Masahiro Takashita, Mariko Shimizu, Soichi Oikawa
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Patent number: 8064244Abstract: 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: GrantFiled: June 19, 2009Date of Patent: November 22, 2011Assignees: TDK Corporation, Kabushiki Kaisha ToshibaInventors: Kunliang Zhang, Min Li, Yuchen Zhou, Soichi Oikawa, Kenichiro Yamada, Katsuhiko Koui
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Publication number: 20110228423Abstract: 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: ApplicationFiled: September 13, 2010Publication date: September 22, 2011Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Katsuhiko Koui, Kenichiro Yamada, Mariko Kitazaki, Hitoshi Iwasaki, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
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Publication number: 20110205667Abstract: 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: ApplicationFiled: August 10, 2010Publication date: August 25, 2011Applicant: Kabushiki Kaisha ToshibaInventors: Kenichiro YAMADA, Katsuhiko KOUI, Mariko KITAZAKI, Masayuki TAKAGISHI, Tomomi FUNAYAMA, Masahiro TAKASHITA, Soichi OIKAWA, Akihiko TAKEO
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Publication number: 20110205655Abstract: 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: ApplicationFiled: February 7, 2011Publication date: August 25, 2011Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Mariko Shimizu, Hitoshi Iwasaki, Kenichiro Yamada, Katsuhiko Koui, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Soichi Oikawa
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Patent number: 7901803Abstract: 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: GrantFiled: October 5, 2004Date of Patent: March 8, 2011Assignees: Showa Denko K.K., Kabushiki Kaisha ToshibaInventors: Tomoyuki Maeda, Soichi Oikawa, Takeshi Iwasaki, Futoshi Nakamura, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
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Patent number: 7901801Abstract: 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: GrantFiled: July 2, 2008Date of Patent: March 8, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Soichi Oikawa, Tomoyuki Maeda
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Patent number: 7867638Abstract: 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: GrantFiled: November 20, 2008Date of Patent: January 11, 2011Assignees: Showa Denko K.K., Kabushiki Kaisha ToshibaInventors: Akira Sakawaki, Kenji Shimizu, Kazuo Kobayashi, Hiroshi Sakai, Soichi Oikawa, Takeshi Iwasaki, Tomoyuki Maeda, Futoshi Nakamura
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Patent number: 7781081Abstract: 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: GrantFiled: December 24, 2004Date of Patent: August 24, 2010Assignees: Showa Denko K.K., Kabushiki Kaisha ToshibaInventors: Tomoyuki Maeda, Soichi Oikawa, Takeshi Iwasaki, Futoshi Nakamura, Hiroshi Sakai, Kenji Shimizu, Akira Sakawaki
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Publication number: 20100142088Abstract: 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: ApplicationFiled: October 6, 2009Publication date: June 10, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Hitoshi Iwasaki, Soichi Oikawa, Katsuhiko Koui, Kenichiro Yamada
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Patent number: 7695832Abstract: 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: GrantFiled: May 26, 2006Date of Patent: April 13, 2010Assignee: Kanushiki Kaisha ToshibaInventor: Soichi Oikawa
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Publication number: 20100073806Abstract: 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: ApplicationFiled: September 15, 2009Publication date: March 25, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Katsuhiko Koui, Hitoshi Iwasaki, Masayuki Takagishi, Kenichiro Yamada, Tomomi Funayama, Masahiro Takashita, Mariko Shimizu, Soichi Oikawa