Patents by Inventor Tadakatsu Ohkubo

Tadakatsu Ohkubo 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: 11915920
    Abstract: The present invention provides a simpler method for sharpening a tip of an emitter. In addition, the present invention provides an emitter including a nanoneedle made of a single crystal material, an emitter including a nanowire made of a single crystal material such as hafnium carbide (HfC), both of which stably emit electrons with high efficiency, and an electron gun and an electronic device using any one of these emitters. A method for manufacturing the emitter according to an embodiment of the present invention comprises processing a single crystal material in a vacuum using a focused ion beam to form an end of the single crystal material, through which electrons are to be emitted, into a tapered shape, wherein the processing is performed in an environment in which a periphery of the single crystal material fixed to a support is opened.
    Type: Grant
    Filed: October 20, 2020
    Date of Patent: February 27, 2024
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Jie Tang, Shuai Tang, Ta-Wei Chiu, Tadakatsu Ohkubo, Jun Uzuhashi, Kazuhiro Hono, Luchang Qin
  • Publication number: 20230066150
    Abstract: A rare-earth magnet according to an embodiment of the present invention comprises: a rare-earth magnet precursor including a composition of (R1(1-x)R2x)yFe(100-y-z-v-w)CozBvTMlw in which R1 comprises at least one of Nd or Pr, and R2 comprises Ce; and a diffusion metal including a composition of (LRE(100-p-q)HREp)TM2q, and diffused on the surface of the rare-earth magnet precursor, wherein the LRE in the diffusion metal can comprise light rare earth including Y, and the HRE can comprise heavy rare earth.
    Type: Application
    Filed: February 6, 2020
    Publication date: March 2, 2023
    Applicants: LG ELECTRONICS INC., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Sunyong SONG, Seok NAMKUNG, Xin TANG, Hossein SEPEHRIAMIN, Tadakatsu OHKUBO, Kazuhiro HONO, Jiangnan LI
  • Patent number: 11585873
    Abstract: A magnetoresistive effect element includes: a first ferromagnetic layer; a second ferromagnetic layer; and a non-magnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer, wherein the non-magnetic layer includes a first layer and a second layer, and wherein a lattice constant ? of the first layer and a lattice constant ? of the second layer satisfy a relationship of ??0.04×??2×???+0.04×?.
    Type: Grant
    Filed: July 8, 2021
    Date of Patent: February 21, 2023
    Assignees: TDK CORPORATION, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinto Ichikawa, Katsuyuki Nakada, Hiroaki Sukegawa, Seiji Mitani, Tadakatsu Ohkubo, Kazuhiro Hono
  • Publication number: 20230049280
    Abstract: The present invention is an alloy that contains Fe, B, P, and Cu, and includes a non-crystalline phase and a plurality of crystalline phases formed in the non-crystalline, wherein an average Fe concentration in a whole alloy is 79 atomic % or greater, and wherein a density of Cu clusters when a region with a Cu concentration of 6.0 atomic % or greater among regions with 1.0 nm on a side in atom probe tomography is determined to be a Cu cluster is 0.20×1024/m3.
    Type: Application
    Filed: December 22, 2020
    Publication date: February 16, 2023
    Applicants: TOHOKU MAGNET INSTITUTE CO., LTD., NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Tatsuya Tomita, Yohei Nomura, Jun Uzuhashi, Tadakatsu Ohkubo, Kazuhiro Hono
  • Publication number: 20230009284
    Abstract: A magnetoresistive effect element includes: a first ferromagnetic layer; a second ferromagnetic layer; and a non-magnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer, wherein the non-magnetic layer includes a first layer and a second layer, and wherein a lattice constant ? of the first layer and a lattice constant ? of the second layer satisfy a relationship of ??0.04×??2×???+0.04 ×?.
    Type: Application
    Filed: July 8, 2021
    Publication date: January 12, 2023
    Applicants: TDK CORPORATION, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinto ICHIKAWA, Katsuyuki NAKADA, Hiroaki SUKEGAWA, Seiji MITANI, Tadakatsu OHKUBO, Kazuhiro HONO
  • Publication number: 20220406552
    Abstract: The present invention provides a simpler method for sharpening a tip of an emitter. In addition, the present invention provides an emitter including a nanoneedle made of a single crystal material, an emitter including a nanowire made of a single crystal material such as hafnium carbide (HfC), both of which stably emit electrons with high efficiency, and an electron gun and an electronic device using any one of these emitters. A method for manufacturing the emitter according to an embodiment of the present invention comprises processing a single crystal material in a vacuum using a focused ion beam to form an end of the single crystal material, through which electrons are to be emitted, into a tapered shape, wherein the processing is performed in an environment in which a periphery of the single crystal material fixed to a support is opened.
    Type: Application
    Filed: October 20, 2020
    Publication date: December 22, 2022
    Applicant: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Jie TANG, Shuai TANG, Ta-Wei CHIU, Tadakatsu OHKUBO, Jun UZUHASHI, Kazuhiro HONO, Luchang QIN
  • Patent number: 11133459
    Abstract: According to one embodiment, a magnetic element includes a first layer and a second layer. The first layer includes a first element and a second element. The first element includes at least one selected from the group consisting of Fe, Co, and Ni. The second element includes at least one selected from the group consisting of Ir and Os. The second layer is nonmagnetic.
    Type: Grant
    Filed: February 15, 2018
    Date of Patent: September 28, 2021
    Assignees: National Institute of Advanced Industrial Science and Technology, TOHOKU UNIVERSITY, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takayuki Nozaki, Shinji Yuasa, Rachwal Anna Koziol, Masahito Tsujikawa, Masafumi Shirai, Kazuhiro Hono, Tadakatsu Ohkubo, Xiandong Xu
  • Patent number: 11105867
    Abstract: The object of the present invention is to attain an unconventionally high tunnel magnetoresistance (TMR) ratio by using a barrier layer made of an MgAl2O4 type insulator material with a spinel structure. The problem can be solved by a magnetic tunnel junction in which a barrier layer is made of a cubic nonmagnetic material having a spinel structure, and both of two ferromagnetic layers that are adjacently on and below the barrier layer are made of a Co2FeAl Heusler alloy. Preferably, the nonmagnetic material is made of oxide of an Mg1?xAlx (0<x?1) alloy, and exhibits tunnel magnetoresistance of 250% or more and 34000% or less at a room temperature.
    Type: Grant
    Filed: January 31, 2017
    Date of Patent: August 31, 2021
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Hiroaki Sukegawa, Thomas Scheike, Seiji Mitani, Tadakatsu Ohkubo, Kazuhiro Hono, Kouichiro Inomata
  • Patent number: 11004465
    Abstract: An object of the present invention is to provide a Magneto-Resistance (MR) element showing a high Magneto-Resistance (MR) ratio and having a suitable Resistance-Area (RA) for device applications. The MR element of the present invention has a laminated structure including a first ferromagnetic layer 16, a non-magnetic layer 18, and a second ferromagnetic layer 20 on a substrate 10, wherein the first ferromagnetic layer 16 includes a Heusler alloy, the second ferromagnetic layer 20 includes a Heusler alloy, the non-magnetic layer 18 includes a I-III-VI2 chalcopyrite-type compound semiconductor, and the non-magnetic layer 18 has a thickness of 0.5 to 3 nm, and wherein the MR element shows a Magneto-Resistance (MR) change of 40% or more, and has a resistance-area (RA) of 0.1 [??m2] or more and 3 [??m2] or less.
    Type: Grant
    Filed: June 23, 2017
    Date of Patent: May 11, 2021
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinya Kasai, Yukiko Takahashi, Pohan Cheng, Ikhtiar, Seiji Mitani, Tadakatsu Ohkubo, Kazuhiro Hono
  • Publication number: 20210123991
    Abstract: The object of the present invention is to attain an unconventionally high tunnel magnetoresistance (TMR) ratio by using a barrier layer made of an MgAl2O4 type insulator material with a spinel structure. The problem can be solved by a magnetic tunnel junction in which a barrier layer is made of a cubic nonmagnetic material having a spinel structure, and both of two ferromagnetic layers that are adjacently on and below the barrier layer are made of a Co2FeAl Heusler alloy. Preferably, the nonmagnetic material is made of oxide of an Mg1-31 xAlx (0<x?1) alloy, and exhibits tunnel magnetoresistance of 250% or more and 34000% or less at a room temperature.
    Type: Application
    Filed: January 31, 2017
    Publication date: April 29, 2021
    Applicant: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Hiroaki SUKEGAWA, Thomas SCHEIKE, Seiji MITANI, Tadakatsu OHKUBO, Kazuhiro HONO, Kouichiro INOMATA
  • Publication number: 20210036217
    Abstract: According to one embodiment, a magnetic element includes a first layer and a second layer. The first layer includes a first element and a second element. The first element includes at least one selected from the group consisting of Fe, Co, and Ni. The second element includes at least one selected from the group consisting of Ir and Os. The second layer is nonmagnetic.
    Type: Application
    Filed: February 15, 2018
    Publication date: February 4, 2021
    Applicants: National Institute of Advanced Industrial Science and Technology, TOHOKU UNIVERSITY, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Takayuki NOZAKI, Shinji YUASA, Rachwal Anna KOZIOL, Masahito TSUJIKAWA, Masafumi SHIRAI, Kazuhiro HONO, Tadakatsu OHKUBO, Xiandong XU
  • Patent number: 10832719
    Abstract: Disclosed is a perpendicularly magnetized film structure using a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow, comprising a substrate of a cubic single crystal substrate having a (001) plane or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer formed on the substrate from a thin film of a metal having an hcp structure in which the [0001] direction of the thin metal film forms an angle in the range of 42° to 54° with respect to the <001> direction or the (001) orientation of the substrate; and a perpendicularly magnetized layer located on the metal underlayer and formed from a cubic material selected from a Co-based Heusler alloy and a cobalt-iron (CoFe) alloy having a bcc structure a constituent material, and grown to have the (001) plane.
    Type: Grant
    Filed: December 10, 2018
    Date of Patent: November 10, 2020
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Hiroaki Sukegawa, Zhenchao Wen, Seiji Mitani, Koichiro Inomata, Takao Furubayashi, Jason Paul Hadorn, Tadakatsu Ohkubo, Kazuhiro Hono, Jungwoo Koo
  • Patent number: 10665776
    Abstract: Provided is a magnetoresistance effect element in which a tunnel barrier layer stably has a cation disordered spinel structure. This magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer disposed between the first ferromagnetic layer and the second ferromagnetic layer. In addition, the tunnel barrier layer is an oxide of MgxAl1-x (0?x<1) and an amount of oxygen in the tunnel barrier layer is lower than an amount of oxygen in a fully oxidized state in which the oxide has an ordered spinel structure.
    Type: Grant
    Filed: February 14, 2019
    Date of Patent: May 26, 2020
    Assignees: TDK CORPORATION, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinto Ichikawa, Katsuyuki Nakada, Seiji Mitani, Hiroaki Sukegawa, Kazuhiro Hono, Tadakatsu Ohkubo
  • Publication number: 20190259937
    Abstract: Provided is a magnetoresistance effect element in which a tunnel barrier layer stably has a cation disordered spinel structure. This magnetoresistance effect element includes a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer disposed between the first ferromagnetic layer and the second ferromagnetic layer. In addition, the tunnel barrier layer is an oxide of MgxAl1-x (0?x<1) and an amount of oxygen in the tunnel barrier layer is lower than an amount of oxygen in a fully oxidized state in which the oxide has an ordered spinel structure.
    Type: Application
    Filed: February 14, 2019
    Publication date: August 22, 2019
    Applicants: TDK CORPORATION, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinto ICHIKAWA, Katsuyuki NAKADA, Seiji MITANI, Hiroaki SUKEGAWA, Kazuhiro HONO, Tadakatsu OHKUBO
  • Publication number: 20190237099
    Abstract: An object of the present invention is to provide a Magneto-Resistance (MR) element showing a high Magneto-Resistance (MR) ratio and having a suitable Resistance-Area (RA) for device applications. The MR element of the present invention has a laminated structure including a first ferromagnetic layer 16, a non-magnetic layer 18, and a second ferromagnetic layer 20 on a substrate 10, wherein the first ferromagnetic layer 16 includes a Heusler alloy, the second ferromagnetic layer 20 includes a Heusler alloy, the non-magnetic layer 18 includes a I-III-VI2 chalcopyrite-type compound semiconductor, and the non-magnetic layer 18 has a thickness of 0.5 to 3 nm, and wherein the MR element shows a Magneto-Resistance (MR) change of 40% or more, and has a resistance-area (RA) of 0.1 [??m2] or more and 3 [??m2] or less.
    Type: Application
    Filed: June 23, 2017
    Publication date: August 1, 2019
    Applicant: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Shinya KASAI, Yukiko TAKAHASHI, Pohan CHENG, IKHTIAR, Seiji MITANI, Tadakatsu OHKUBO, Kazuhiro HONO
  • Publication number: 20190172486
    Abstract: Disclosed is a perpendicularly magnetized film structure using a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow, comprising a substrate of a cubic single crystal substrate having a (001) plane or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer formed on the substrate from a thin film of a metal having an hcp structure in which the [0001] direction of the thin metal film forms an angle in the range of 42° to 54° with respect to the <001> direction or the (001) orientation of the substrate; and a perpendicularly magnetized layer located on the metal underlayer and formed from a cubic material selected from a Co-based Heusler alloy and a cobalt-iron (CoFe) alloy having a bcc structure a constituent material, and grown to have the (001) plane.
    Type: Application
    Filed: December 10, 2018
    Publication date: June 6, 2019
    Applicant: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Hiroaki SUKEGAWA, Zhenchao WEN, Seiji MITANI, Koichiro INOMATA, Takao FURUBAYASHI, Jason Paul HADORN, Tadakatsu OHKUBO, Kazuhiro HONO, Jungwoo KOO
  • Patent number: 10305027
    Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer, a second magnetic layer, and a first nonmagnetic layer. The first nonmagnetic layer is provided between the first magnetic layer and the second magnetic layer. The first nonmagnetic layer includes an oxide including an inverse-spinel structure.
    Type: Grant
    Filed: September 8, 2017
    Date of Patent: May 28, 2019
    Assignees: Kabushiki Kaisha Toshiba, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Yushi Kato, Tadaomi Daibou, Yuuzo Kamiguchi, Naoharu Shimomura, Junichi Ito, Hiroaki Sukegawa, Mohamed Belmoubarik, Po-Han Cheng, Seiji Mitani, Tadakatsu Ohkubo, Kazuhiro Hono
  • Patent number: 10199063
    Abstract: Disclosed is a perpendicularly magnetized film structure that uses a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow with high quality, the structure comprising any one substrate (5) of a cubic single crystal substrate having a (001) plane, or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer (6) formed on the substrate (5) from a thin film of a metal having an hcp structure, such as Ru or Re, in which the [0001] direction of the thin metal film forms an angle in the range of 42° to 54° with respect to the <001> direction or the (001) orientation of the substrate (5); and a perpendicularly magnetized layer (7) located on the metal underlayer (6) and formed from a cubic material selected from the group consisting of a Co-based Heusler alloy, a cobalt-iron (CoFe) alloy having a bcc structure, and the like, as a constituent material, and grown to have the (001) plane.
    Type: Grant
    Filed: March 19, 2015
    Date of Patent: February 5, 2019
    Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Hiroaki Sukegawa, Zhenchao Wen, Seiji Mitani, Koichiro Inomata, Takao Furubayashi, Jason Paul Hadorn, Tadakatsu Ohkubo, Kazuhiro Hono, Jungwoo Koo
  • Publication number: 20180090671
    Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer, a second magnetic layer, and a first nonmagnetic layer. The first nonmagnetic layer is provided between the first magnetic layer and the second magnetic layer. The first nonmagnetic layer includes an oxide including an inverse-spinel structure.
    Type: Application
    Filed: September 8, 2017
    Publication date: March 29, 2018
    Applicants: Kabushiki Kaisha Toshiba, NATIONAL INSTITUTE FOR MATERIALS SCIENCE
    Inventors: Yushi KATO, Tadaomi DAIBOU, Yuuzo KAMIGUCHI, Naoharu SHIMOMURA, Junichi ITO, Hiroaki SUKEGAWA, Mohamed BELMOUBARIK, Po-Han CHENG, Seiji MITANI, Tadakatsu OHKUBO, Kazuhiro HONO
  • Patent number: 9842636
    Abstract: Provided is a structure having a perpendicular magnetization film which is an (Mn1-xGax)4N1-y (0<x?0.5, 0<y<1) thin film having a nitrogen-deficient composition which is formed by controlling and introducing nitrogen N into an MnGa alloy or a thin film containing at least one of Ge, Zn, Sb, Ni, Ag, Sn, Pt, and Rh, instead of Ga. The perpendicular magnetization film exhibits a Curie temperature sufficiently higher than room temperature, has saturation magnetization smaller than that of existing materials, and is capable of being fabricated as a very flat film.
    Type: Grant
    Filed: April 21, 2016
    Date of Patent: December 12, 2017
    Assignees: NATIONAL INSTITUTE FOR MATERIALS SCIENCE, SAMSUNG ELECTRONICS COMPANY LIMITED
    Inventors: Hiroaki Sukegawa, Hwachol Lee, Kazuhiro Hono, Seiji Mitani, Tadakatsu Ohkubo, Jun Liu, Shinya Kasai, Kwangseok Kim