Patents by Inventor Hiroaki Yoda

Hiroaki Yoda 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: 20120088125
    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: Application
    Filed: September 19, 2011
    Publication date: April 12, 2012
    Applicants: NATIONAL UNIVERSITY CORPORATION TOHOKU UNIVERSITY, KABUSHIKI KAISHA TOSHIBA
    Inventors: Katsuya NISHIYAMA, Wu Feng, Chunlan Feng, 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
  • Patent number: 8154915
    Abstract: The present invention provides a low-resistance magnetoresistive element of a spin-injection write type. A crystallization promoting layer that promotes crystallization is formed in contact with an interfacial magnetic layer having an amorphous structure, so that crystallization is promoted from the side of a tunnel barrier layer, and the interface between the tunnel barrier layer and the interfacial magnetic layer is adjusted. With this arrangement, it is possible to form a magnetoresistive element that has a low resistance so as to obtain a desired current value, and has a high TMR ratio.
    Type: Grant
    Filed: May 20, 2011
    Date of Patent: April 10, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20120074511
    Abstract: A magnetic memory according to an embodiment includes: at least one memory cell comprising a magnetoresistive element as a memory element, and first and second electrodes that energize the magnetoresistive element. The magnetoresistive element includes: a first magnetic layer having a variable magnetization direction perpendicular to a film plane; a tunnel barrier layer on the first magnetic layer; and a second magnetic layer on the tunnel barrier layer, and having a fixed magnetization direction perpendicular to the film plane. The first magnetic layer including: a first region; and a second region outside the first region so as to surround the first region, and having a smaller perpendicular magnetic anisotropy energy than that of the first region. The second magnetic layer including: a third region; and a fourth region outside the third region, and having a smaller perpendicular magnetic anisotropy energy than that of the third region.
    Type: Application
    Filed: September 13, 2011
    Publication date: March 29, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Shigeki TAKAHASHI, Yuichi OHSAWA, Junichi ITO, Chikayoshi KAMATA, Saori KASHIWADA, Minoru AMANO, Hiroaki YODA
  • Publication number: 20120069640
    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: Application
    Filed: September 14, 2011
    Publication date: March 22, 2012
    Applicant: 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
  • Publication number: 20120070695
    Abstract: According to one embodiment, a magnetoresistive element includes a recording layer having a variable magnetization direction, a reference layer having an invariable magnetization direction, an intermediate layer provided between the recording layer and the reference layer, and a first buffer layer provided on a surface of the recording layer, which is opposite to a surface of the recording layer where the intermediate layer is provided. The recording layer comprises a first magnetic layer which is provided in a side of the intermediate layer and contains CoFe as a main component, and a second magnetic layer which is provided in a side of the first buffer layer and contains CoFe as a main component, a concentration of Fe in the first magnetic layer being higher than a concentration of Fe in the second magnetic layer. The first buffer layer comprises a nitrogen compound.
    Type: Application
    Filed: September 16, 2011
    Publication date: March 22, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Eiji Kitagawa, Tadaomi Daibou, Tadashi Kai, Toshihiko Nagase, Kenji Noma, Hiroaki Yoda
  • Publication number: 20120069642
    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: Application
    Filed: September 19, 2011
    Publication date: March 22, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Koji Ueda, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Hiroaki Yoda
  • Publication number: 20120068284
    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: Application
    Filed: September 15, 2011
    Publication date: March 22, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Eiji Kitagawa, Tadaomi Daibou, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda
  • Publication number: 20120068139
    Abstract: A magnetoresistive element according to an embodiment includes: a first ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a second ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a nonmagnetic layer placed between the first ferromagnetic layer and the second ferromagnetic layer; a first interfacial magnetic layer placed between the first ferromagnetic layer and the nonmagnetic layer; and a second interfacial magnetic layer placed between the second ferromagnetic layer and the nonmagnetic layer. The first interfacial magnetic layer includes a first interfacial magnetic film, a second interfacial magnetic film placed between the first interfacial magnetic film and the nonmagnetic layer and having a different composition from that of the first interfacial magnetic film, and a first nonmagnetic film placed between the first interfacial magnetic film and the second interfacial magnetic film.
    Type: Application
    Filed: March 8, 2011
    Publication date: March 22, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tadaomi Daibou, Eiji Kitagawa, Yutaka Hashimoto, Masaru Tokou, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Makoto Nagamine, Tadashi Kai, Hiroaki Yoda
  • Publication number: 20120068285
    Abstract: According to one embodiment, a magnetoresistive effect element includes a first magnetic layer including perpendicular anisotropy to a film surface and an invariable magnetization direction, the first magnetic layer having a magnetic film including an element selected from a first group including Tb, Gd, and Dy and an element selected from a second group including Co and Fe, a second magnetic layer including perpendicular magnetic anisotropy to the film surface and a variable magnetization direction, and a nonmagnetic layer between the first magnetic layer and the second magnetic layer. The magnetic film includes amorphous phases and crystals whose particle sizes are 0.5 nm or more.
    Type: Application
    Filed: September 16, 2011
    Publication date: March 22, 2012
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Eiji KITAGAWA, Tadaomi Daibou, Yutaka Hashimoto, Masaru Tokou, Tadashi Kai, Makoto Nagamine, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
  • Patent number: 8139405
    Abstract: The present invention provides a low-resistance magnetoresistive element of a spin-injection write type. A crystallization promoting layer that promotes crystallization is formed in contact with an interfacial magnetic layer having an amorphous structure, so that crystallization is promoted from the side of a tunnel barrier layer, and the interface between the tunnel barrier layer and the interfacial magnetic layer is adjusted. With this arrangement, it is possible to form a magnetoresistive element that has a low resistance so as to obtain a desired current value, and has a high TMR ratio.
    Type: Grant
    Filed: May 5, 2011
    Date of Patent: March 20, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 8139403
    Abstract: Certain embodiments provide a spin memory including a memory cell including a ferromagnetic stacked film that has a stacked structure in which a first ferromagnetic layer, a first nonmagnetic layer, a second ferromagnetic layer, a second nonmagnetic layer, and a third ferromagnetic layer are stacked in this order or reverse order, the third ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically exchange-coupled via the second nonmagnetic layer. The ferromagnetic stacked film includes a current path in which a first and second write currents flow from the first ferromagnetic layer to the third ferromagnetic layer to write a first and second magnetization states into the first ferromagnetic layer respectively, and the second write current is higher than the first write current.
    Type: Grant
    Filed: September 20, 2010
    Date of Patent: March 20, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tomoaki Inokuchi, Takao Marukame, Mizue Ishikawa, Hideyuki Sugiyama, Hisanori Aikawa, Masahiko Nakayama, Tatsuya Kishi, Hiroaki Yoda, Yoshiaki Saito
  • Patent number: 8120948
    Abstract: A data writing method for a magnetoresistive effect element of an aspect of the present invention including generating a write current in which a falling period from the start of a falling edge to the end of the falling edge is longer than a rising period from the start of a rising edge to the end of the rising edge, and flowing the write current through the magnetoresistive effect element which comprises a first magnetic layer having an invariable magnetizing direction, a second magnetic layer having a variable magnetizing direction, and a tunnel barrier layer provided between the first magnetic layer and the second magnetic layer, to change the magnetizing direction of the second magnetic layer.
    Type: Grant
    Filed: September 17, 2009
    Date of Patent: February 21, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Hisanori Aikawa, Tsuneo Inaba, Kenji Tsuchida, Sumio Ikegawa, Hiroaki Yoda, Naoharu Shimomura
  • Patent number: 8107281
    Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer with a variable magnetization and an easy-axis in a perpendicular direction to a film surface, a second magnetic layer with an invariable magnetization and an easy-axis in the perpendicular direction, and a first nonmagnetic layer between the first and second magnetic layers. The first magnetic layer comprises a ferromagnetic material including an alloy in which Co and Pd, or Co and Pt are alternately laminated on an atomically close-packed plane thereof. The first magnetic layer has C-axis directing the perpendicular direction. And a magnetization direction of the first magnetic layer is changed by a current flowing through the first magnetic layer, the first nonmagnetic layer and the second magnetic layer.
    Type: Grant
    Filed: September 10, 2010
    Date of Patent: January 31, 2012
    Assignees: Kabushiki Kaisha Toshiba, National Institute of Advanced Industrial Science and Technology
    Inventors: Tadashi Kai, Katsuya Nishiyama, Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Masahiko Nakayama, Naoharu Shimomura, Hiroaki Yoda, Kei Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
  • Patent number: 8098514
    Abstract: A magnetoresistive element includes a first reference layer having magnetic anisotropy perpendicular to a film surface, and an invariable magnetization, a recording layer having a stacked structure formed by alternately stacking magnetic layers and nonmagnetic layers, magnetic anisotropy perpendicular to a film surface, and a variable magnetization, and an intermediate layer provided between the first reference layer and the recording layer, and containing a nonmagnetic material. The magnetic layers include a first magnetic layer being in contact with the intermediate layer and a second magnetic layer being not in contact with the intermediate layer. The first magnetic layer contains an alloy containing cobalt (Co) and iron (Fe), and has a film thickness larger than that of the second magnetic layer.
    Type: Grant
    Filed: September 18, 2008
    Date of Patent: January 17, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Katsuya Nishiyama, Tadashi Kai, Masahiko Nakayama, Makoto Nagamine, Minoru Amano, Masatoshi Yoshikawa, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20120008381
    Abstract: A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0?Ms<?{square root over ( )}{Jw/(6?At)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.
    Type: Application
    Filed: September 15, 2011
    Publication date: January 12, 2012
    Inventors: Toshihiko NAGASE, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20110309418
    Abstract: A magnetoresistance effect element includes: a first ferromagnetic layer having invariable magnetization perpendicular to a film plane; a second ferromagnetic layer having variable magnetization perpendicular to the film plane; a first nonmagnetic layer interposed between the first ferromagnetic layer and the second ferromagnetic layer; a third ferromagnetic layer provided on an opposite side of the second ferromagnetic layer from the first nonmagnetic layer, and having variable magnetization parallel to the film plane; and a second nonmagnetic layer interposed between the second and third ferromagnetic layers.
    Type: Application
    Filed: July 18, 2011
    Publication date: December 22, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masahiko NAKAYAMA, Tadashi Kai, Sumio Ikegawa, Hiroaki Yoda, Tatsuya Kishi
  • Patent number: 8036025
    Abstract: A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0?Ms<?{square root over ( )}{Jw/(6?At)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.
    Type: Grant
    Filed: January 12, 2010
    Date of Patent: October 11, 2011
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Masatoshi Yoshkawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20110227179
    Abstract: A magnetoresistive element according to an embodiment includes: a first magnetic layer; a tunnel barrier layer on the first magnetic layer; a second magnetic layer placed on the tunnel barrier layer and containing CoFe; and a nonmagnetic layer placed on the second magnetic layer, and containing nitrogen and at least one element selected from the group consisting of B, Ta, Zr, Al, and Ce.
    Type: Application
    Filed: March 17, 2011
    Publication date: September 22, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Eiji KITAGAWA, Tadashi KAI, Tadaomi DAIBOU, Yutaka HASHIMOTO, Hiroaki YODA
  • Publication number: 20110228596
    Abstract: Certain embodiments provide a spin memory including a memory cell including a ferromagnetic stacked film that has a stacked structure in which a first ferromagnetic layer, a first nonmagnetic layer, a second ferromagnetic layer, a second nonmagnetic layer, and a third ferromagnetic layer are stacked in this order or reverse order, the third ferromagnetic layer and the second ferromagnetic layer being antiferromagnetically exchange-coupled via the second nonmagnetic layer. The ferromagnetic stacked film includes a current path in which a first and second write currents flow from the first ferromagnetic layer to the third ferromagnetic layer to write a first and second magnetization states into the first ferromagnetic layer respectively, and the second write current is higher than the first write current.
    Type: Application
    Filed: September 20, 2010
    Publication date: September 22, 2011
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Tomoaki Inokuchi, Takao Marukame, Mizue Ishikawa, Hideyuki Sugiyama, Hisanori Aikawa, Masahiko Nakayama, Tatsuya Kishi, Hiroaki Yoda, Yoshiaki Saito
  • Publication number: 20110222335
    Abstract: The present invention provides a low-resistance magnetoresistive element of a spin-injection write type. A crystallization promoting layer that promotes crystallization is formed in contact with an interfacial magnetic layer having an amorphous structure, so that crystallization is promoted from the side of a tunnel barrier layer, and the interface between the tunnel barrier layer and the interfacial magnetic layer is adjusted. With this arrangement, it is possible to form a magnetoresistive element that has a low resistance so as to obtain a desired current value, and has a high TMR ratio.
    Type: Application
    Filed: May 20, 2011
    Publication date: September 15, 2011
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi YOSHIKAWA, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda