Patents by Inventor Tadashi Kai

Tadashi Kai 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: 8953369
    Abstract: According to one embodiment, a magnetoresistive element includes first and second magnetic layers and a first nonmagnetic layer. The first magnetic layer has an axis of easy magnetization perpendicular to a film plane, and a variable magnetization. The second magnetic layer has an axis of easy magnetization perpendicular to a film plane, and an invariable magnetization. The first nonmagnetic layer is provided between the first and second magnetic layers. The second magnetic layer includes third and fourth magnetic layers, and a second nonmagnetic layer formed between the third and fourth magnetic layers. The third magnetic layer is in contact with the first nonmagnetic layer and includes Co and at least one of Zr, Nb, Mo, Hf, Ta, and W.
    Type: Grant
    Filed: January 20, 2014
    Date of Patent: February 10, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Eiji Kitagawa, Katsuya Nishiyama, Tadashi Kai, Koji Ueda, Daisuke Watanabe
  • Patent number: 8946837
    Abstract: According to one embodiment, a semiconductor storage device is disclosed. The device includes first magnetic layer, second magnetic layer, first nonmagnetic layer between them. The first magnetic layer includes a structure in which first magnetic material film, second magnetic material film, and nonmagnetic material film between the first and second magnetic material films are stacked. The first magnetic material film is nearest to the first nonmagnetic layer in the first magnetic layer. The nonmagnetic material film includes at least one of Ta, Zr, Nb, Mo, Ru, Ti, V, Cr, W, Hf. The second magnetic material film includes stacked materials, including first magnetic material nearest to the first nonmagnetic layer among the stacked materials, and second magnetic material which is same magnetic material as the first magnetic material and has smaller thickness than the first magnetic material.
    Type: Grant
    Filed: January 10, 2014
    Date of Patent: February 3, 2015
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Daisuke Watanabe, Katsuya Nishiyama, Toshihiko Nagase, Koji Ueda, Tadashi Kai
  • Patent number: 8895162
    Abstract: A magnetoresistive element according to an embodiment includes: a base layer; a first magnetic layer formed on the base layer and having a changeable magnetization direction with an easy axis of magnetization in a direction perpendicular to a film plane; a first nonmagnetic layer formed on the first magnetic layer; and a second magnetic layer formed on the first nonmagnetic layer and having a fixed magnetization layer with an easy axis of magnetization in a direction perpendicular to the film plane. The first magnetic layer includes a ferrimagnetic layer having a DO22 structure or an L10 structure, the ferrimagnetic layer has a c-axis oriented in a direction perpendicular to the film plane, and the magnetization direction of the first magnetic layer is changeable by a current flowing through the first magnetic layer, the first nonmagnetic layer, and the second magnetic layer.
    Type: Grant
    Filed: September 19, 2011
    Date of Patent: November 25, 2014
    Assignees: Kabushiki Kaisha Toshiba, National University Corporation Tohoku University
    Inventors: Katsuya Nishiyama, Shigemi Mizukami, Terunobu Miyazaki, Hiroaki Yoda, Tadashi Kai, Tatsuya Kishi, Daisuke Watanabe, Mikihiko Oogane, Yasuo Ando, Masatoshi Yoshikawa, Toshihiko Nagase, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Chunlan Feng
  • Publication number: 20140284539
    Abstract: According to one embodiment, a magnetoresistive element includes first and magnetic layers, first and second non-magnetic layers and a W layer. Each of the first and second magnetic layers includes an axis of easy magnetization in a direction perpendicular to a film plane. The first magnetic layer has a variable magnetization direction. The second magnetic layer has an invariable magnetization direction. The first non-magnetic layer is provided between the first and second magnetic layers. The second non-magnetic layer is arranged on a surface of the first magnetic layer opposite to a surface on which the first non-magnetic layer is arranged and contains MgO. The W layer is arranged on a surface of the second non-magnetic layer opposite to a surface on which the first magnetic layer is arranged, and is in contact with the surface of the second non-magnetic layer.
    Type: Application
    Filed: August 9, 2013
    Publication date: September 25, 2014
    Inventors: Youngmin EEH, Katsuya NISHIYAMA, Daisuke IKENO, Toshihiko NAGASE, Tadashi KAI, Daisuke WATANABE
  • Publication number: 20140284534
    Abstract: According to one embodiment, a magnetoresistive element is disclosed. The magnetoresistive element includes a first magnetic layer having a variable magnetization direction. A first nonmagnetic layer is provided on the first magnetic layer. A second magnetic layer having a fixed magnetization direction is provided on the first nonmagnetic layer. The first magnetic layer, the first nonmagnetic layer and the second magnetic layer are preferredly oriented in a cubical crystal (111) plane.
    Type: Application
    Filed: September 11, 2013
    Publication date: September 25, 2014
    Inventors: Toshihiko NAGASE, Tadashi KAI, Youngmin EEH, Koji UEDA, Daisuke WATANABE, Kazuya SAWADA, Hiroaki YODA
  • Publication number: 20140284742
    Abstract: According to one embodiment, a magnetoresistive element includes first, second and third magnetic layers, and first and second nonmagnetic layers. The third magnetic layer has stack layers including a first stack layer close to the second magnetic layer, and a second stack layer far from the second magnetic layer. Each of the first and second stack layers includes a first layer made of a ferromagnetic material and a second layer made of a nonmagnetic material, and a first ratio of a film thickness of the first layer to that of the second layer in the first stack layer is higher than a second ratio of a film thickness of the first layer to that of the second layer in the second stack layer.
    Type: Application
    Filed: August 9, 2013
    Publication date: September 25, 2014
    Inventors: Kazuya SAWADA, Toshihiko NAGASE, Youngmin EEH, Koji UEDA, Daisuke WATANABE, Masahiko NAKAYAMA, Tadashi KAI, Hiroaki YODA
  • Publication number: 20140284735
    Abstract: According to one embodiment, a magnetoresistance effect element includes a reference layer, a shift canceling layer, a storage layer provided between the reference layer and the shift canceling layer, a tunnel barrier layer provided between the reference layer and the storage layer, and a spacer layer provided between the shift canceling layer and the storage layer, wherein a pattern of the storage layer is provided inside a pattern of the shift canceling layer when the patterns of the storage layer and the shift canceling layer are viewed from a direction perpendicular to the patterns of the storage layer and the shift canceling layer.
    Type: Application
    Filed: August 29, 2013
    Publication date: September 25, 2014
    Inventors: Masahiko NAKAYAMA, Toshihiko NAGASE, Tadashi KAI, Youngmin EEH, Koji UEDA, Yutaka HASHIMOTO, Daisuke WATANABE, Kazuya SAWADA
  • Publication number: 20140159177
    Abstract: A magnetoresistive element according to an embodiment includes: a base layer; a first magnetic layer formed on the base layer, and including a first magnetic film having an axis of easy magnetization in a direction perpendicular to a film plane, the first magnetic film including MnxGa100-x (45?x<64 atomic %); a first nonmagnetic layer formed on the first magnetic layer; and a second magnetic layer formed on the first nonmagnetic layer, and including a second magnetic film having an axis of easy magnetization In a direction perpendicular to a film plane, the second magnetic film including MnyGa100-y (45?y<64 atomic %). The first and second magnetic layers include different Mn composition rates from each other, a magnetization direction of the first magnetic layer is changeable by a current flowing between the first magnetic layer and the second magnetic layer via the first nonmagnetic layer.
    Type: Application
    Filed: February 18, 2014
    Publication date: June 12, 2014
    Applicants: WPI-AIMR, Tohoku University, Kabushiki Kaisha Toshiba
    Inventors: Tadaomi DAIBOU, Junichi Ito, Tadashi Kai, Minoru Amano, Hiroaki Yoda, Terunobu Miyazaki, Shigemi Mizukami, Koji Ando, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Akio Fukushima, Taro Nagahama, Takahide Kubota
  • Patent number: 8750029
    Abstract: According to one embodiment, a magnetoresistive effect element includes a recording layer including ferromagnetic material with perpendicular magnetic anisotropy to a film surface and a variable orientation of magnetization, a reference layer including ferromagnetic material with perpendicular magnetic anisotropy to a film surface and an invariable orientation of magnetization, a nonmagnetic layer between the recording layer and the reference layer, a first underlayer on a side of the recoding layer opposite to a side on which the nonmagnetic layer is provided, and a second underlayer between the recording layer and the first underlayer. The second underlayer is a Pd film including a concentration of 3×1015 atms/cm2.
    Type: Grant
    Filed: September 15, 2011
    Date of Patent: June 10, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Tadaomi Daibou, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda
  • Patent number: 8750030
    Abstract: According to one embodiment, a magnetoresistive element includes an electrode layer, a first magnetic layer, a second magnetic layer and a nonmagnetic layer. The electrode layer includes a metal layer including at least one of Mo, Nb, and W. The first magnetic layer is disposed on the metal layer to be in contact with the metal layer and has a magnetization easy axis in a direction perpendicular to a film plane and is variable in magnetization direction. The second magnetic layer is disposed on the first magnetic layer and has a magnetization easy axis in the direction perpendicular to the film plane and is invariable in magnetization direction. The nonmagnetic layer is provided between the first and second magnetic layers. The magnetization direction of the first magnetic layer is varied by a current that runs through the first magnetic layer, the nonmagnetic layer, and the second magnetic layer.
    Type: Grant
    Filed: September 19, 2011
    Date of Patent: June 10, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Ueda, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Hiroaki Yoda
  • Publication number: 20140131824
    Abstract: According to one embodiment, a magnetoresistive element includes a recording layer having magnetic anisotropy perpendicular to a film surface and having a variable magnetization direction, a reference layer having magnetic anisotropy perpendicular to a film surface and having an invariable magnetization direction, an intermediate layer provided between the recording layer and the reference layer, and a underlayer containing AlTiN and provided on an opposite side of a surface of the recording layer on which the intermediate layer is provided.
    Type: Application
    Filed: January 21, 2014
    Publication date: May 15, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Tadashi Kai, Hiroaki Yoda
  • Publication number: 20140131823
    Abstract: According to one embodiment, a magnetoresistive element includes first and second magnetic layers and a first nonmagnetic layer. The first magnetic layer has an axis of easy magnetization perpendicular to a film plane, and a variable magnetization. The second magnetic layer has an axis of easy magnetization perpendicular to a film plane, and an invariable magnetization. The first nonmagnetic layer is provided between the first and second magnetic layers. The second magnetic layer includes third and fourth magnetic layers, and a second nonmagnetic layer formed between the third and fourth magnetic layers. The third magnetic layer is in contact with the first nonmagnetic layer and includes Co and at least one of Zr, Nb, Mo, Hf, Ta, and W.
    Type: Application
    Filed: January 20, 2014
    Publication date: May 15, 2014
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Toshihiko Nagase, Eiji Kitagawa, Katsuya Nishiyama, Tadashi Kai, Koji Ueda, Daisuke Watanabe
  • Publication number: 20140124884
    Abstract: According to one embodiment, a semiconductor storage device is disclosed. The device includes first magnetic layer, second magnetic layer, first nonmagnetic layer between them. The first magnetic layer includes a structure in which first magnetic material film, second magnetic material film, and nonmagnetic material film between the first and second magnetic material films are stacked. The first magnetic material film is nearest to the first nonmagnetic layer in the first magnetic layer. The nonmagnetic material film includes at least one of Ta, Ar, Nb, Mo, Ru, Ti, V, Cr, W, Hf. The second magnetic material film includes a stacked materials, including first magnetic material nearest to the first nonmagnetic layer among the stacked materials, and second magnetic material which is same magnetic material as the first magnetic material and has smaller thickness than the first magnetic material.
    Type: Application
    Filed: January 10, 2014
    Publication date: May 8, 2014
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Daisuke Watanabe, Katsuya Nishiyama, Toshihiko Nagase, Koji Ueda, Tadashi Kai
  • Publication number: 20140119109
    Abstract: According to one embodiment, a magnetoresistive element includes first and second magnetic layers, a first nonmagnetic layer, a conductive layer. The first and second magnetic layers have axes of easy magnetization perpendicular to a film plane. The first and second magnetic layers have variable and invariable magnetization directions, respectively. The first nonmagnetic layer is between the first and second magnetic layers. The conductive layer is on a surface of the first magnetic layer opposite to a surface on which the first nonmagnetic layer is formed. The first magnetic layer has a structure obtained by alternately laminating magnetic and nonmagnetic materials. The nonmagnetic material includes at least one of Ta, W, Nb, Mo, Zr, Hf. The magnetic material includes Co and Fe. One of the magnetic materials contacts the first nonmagnetic layer. One of the nonmagnetic materials contacts the conductive layer.
    Type: Application
    Filed: January 3, 2014
    Publication date: May 1, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Daisuke Watanabe, Koji Ueda, Katsuya Nishiyama, Eiji Kitagawa, Kenji Noma, Tadashi Kai
  • Patent number: 8710604
    Abstract: In accordance with an embodiment, a magnetoresistive element includes a lower electrode, a first magnetic layer on the lower electrode, a first diffusion prevention layer on the first magnetic layer, a first interfacial magnetic layer on the first metal layer, a nonmagnetic layer on the first interfacial magnetic layer, a second interfacial magnetic layer on the nonmagnetic layer, a second diffusion prevention layer on the second interfacial magnetic layer, a second magnetic layer on the second diffusion prevention layer, and an upper electrode layer on the second magnetic layer. The ratio of a crystal-oriented part to the other part in the second interfacial magnetic layer is higher than the ratio of a crystal-oriented part to the other part in the first interfacial magnetic layer.
    Type: Grant
    Filed: March 20, 2012
    Date of Patent: April 29, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Yamakawa, Katsuaki Natori, Daisuke Ikeno, Tadashi Kai
  • Patent number: 8705269
    Abstract: A magnetoresistive element according to an embodiment includes: a first and second magnetic layers having an easy axis of magnetization in a direction perpendicular to a film plane; and a first nonmagnetic layer interposed between the first and second magnetic layers, at least one of the first and second magnetic layers including a structure formed by stacking a first and second magnetic films, the second magnetic film being located closer to the first nonmagnetic layer, the second magnetic film including a structure formed by repeating stacking of a magnetic material layer and a nonmagnetic material layer at least twice, the nonmagnetic material layers of the second magnetic film containing at least one element selected from the group consisting of Ta, W, Hf, Zr, Nb, Mo, Ti, V, and Cr, one of the first and second magnetic layers having a magnetization direction that is changed by applying a current.
    Type: Grant
    Filed: September 14, 2011
    Date of Patent: April 22, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Tadashi Kai, Makoto Nagamine, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
  • Patent number: 8680632
    Abstract: A magnetoresistive element according to an embodiment includes: a base layer; a first magnetic layer formed on the base layer, and including a first magnetic film having an axis of easy magnetization in a direction perpendicular to a film plane, the first magnetic film including MnxGa100-x (45?x<64 atomic %); a first nonmagnetic layer formed on the first magnetic layer; and a second magnetic layer formed on the first nonmagnetic layer, and including a second magnetic film having an axis of easy magnetization in a direction perpendicular to a film plane, the second magnetic film including MnyGa100-y (45?y<64 atomic %). The first and second magnetic layers include different Mn composition rates from each other, a magnetization direction of the first magnetic layer is changeable by a current flowing between the first magnetic layer and the second magnetic layer via the first nonmagnetic layer.
    Type: Grant
    Filed: December 2, 2011
    Date of Patent: March 25, 2014
    Assignees: Kabushiki Kaisha Toshiba, WPI-AIMR, Tohoku University
    Inventors: Tadaomi Daibou, Junichi Ito, Tadashi Kai, Minoru Amano, Hiroaki Yoda, Terunobu Miyazaki, Shigemi Mizukami, Koji Ando, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Akio Fukushima, Taro Nagahama, Takahide Kubota
  • Patent number: 8669628
    Abstract: According to one embodiment, a magnetoresistive element includes the following configuration. First nonmagnetic layer is provided between the first magnetic layer (storage layer) and the second magnetic layer (reference layer). Third magnetic layer is formed on a surface of the storage layer, which is opposite to a surface on which the first nonmagnetic layer is formed. Fourth magnetic layer is formed on a surface of the reference layer, which is opposite to a surface on which the first nonmagnetic layer is formed. The third and fourth magnetic layers have a magnetization antiparallel to the magnetization of the storage layer. Second nonmagnetic layer is located between the storage and third magnetic layers. Third nonmagnetic layer is located between the reference and fourth magnetic layers. The thickness of the fourth magnetic layer is smaller than that of the third magnetic layer.
    Type: Grant
    Filed: March 19, 2012
    Date of Patent: March 11, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Koji Ueda, Katsuya Nishiyama, Toshihiko Nagase, Daisuke Watanabe, Eiji Kitagawa, Tadashi Kai
  • Patent number: 8670268
    Abstract: According to one embodiment, a magnetoresistive element includes first and second magnetic layers and a first nonmagnetic layer. The first magnetic layer has an axis of easy magnetization perpendicular to a film plane, and a variable magnetization. The second magnetic layer has an axis of easy magnetization perpendicular to a film plane, and an invariable magnetization. The first nonmagnetic layer is provided between the first and second magnetic layers. The second magnetic layer includes third and fourth magnetic layers, and a second nonmagnetic layer formed between the third and fourth magnetic layers. The third magnetic layer is in contact with the first nonmagnetic layer and includes Co and at least one of Zr, Nb, Mo, Hf, Ta, and W.
    Type: Grant
    Filed: March 22, 2012
    Date of Patent: March 11, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Eiji Kitagawa, Katsuya Nishiyama, Tadashi Kai, Koji Ueda, Daisuke Watanabe
  • Patent number: 8665639
    Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer with a perpendicular and variable magnetization, a second magnetic layer with a perpendicular and invariable magnetization, and a first nonmagnetic layer between the first and second magnetic layer. The first magnetic layer has a laminated structure of first and second ferromagnetic materials. A magnetization direction of the first magnetic layer is changed by a current which pass through the first magnetic layer, the first nonmagnetic layer and the second magnetic layer. A perpendicular magnetic anisotropy of the second ferromagnetic material is smaller than that of the first ferromagnetic material. A film thickness of the first ferromagnetic material is thinner than that of the second ferromagnetic material.
    Type: Grant
    Filed: February 28, 2012
    Date of Patent: March 4, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Tadashi Kai, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Masahiko Nakayama, Makoto Nagamine, Shigeto Fukatsu, Masatoshi Yoshikawa, Hiroaki Yoda