Patents by Inventor Masatoshi Yoshikawa

Masatoshi Yoshikawa 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: 7787288
    Abstract: An inadvertent write can be prevented when a read is performed. The duration of the write current pulse for writing information in the magnetic memory layer is longer than the duration of the read current pulse for reading the information from the magnetic memory layer.
    Type: Grant
    Filed: July 27, 2007
    Date of Patent: August 31, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Masatoshi Yoshikawa, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7768824
    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: September 16, 2008
    Date of Patent: August 3, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7738220
    Abstract: A magnetoresistance effect element, comprising a nonmagnetic spacer layer, first and second ferromagnetic layers separated by the nonmagnetic spacer layer, the first ferromagnetic layer having a magnetization direction at an angle relative to a magnetization direction of the second ferromagnetic layer at zero applied magnetic field, the magnetization of the first ferromagnetic layer freely rotating in a magnetic field signal, a magnetoresistance effect-improving layer comprising a plurality of metal films and disposed in contact with the first ferromagnetic layer so that the first ferromagnetic layer is disposed between the nonmagnetic spacer layer and the magnetoresistance effect-improving layer, one of the plurality of metal films disposed in contact with the first ferromagnetic layer contains metal element of not solid solution with metal element of the first ferromagnetic layer and a nonmagnetic underlayer or a nonmagnetic protecting layer disposed in contact with the magnetoresistance effect-improving la
    Type: Grant
    Filed: July 17, 2007
    Date of Patent: June 15, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Yuzo Kamiguchi, Katsuhiko Koui, Shin-ichi Nakamura, Hitoshi Iwasaki, Kazuhiro Saito, Hiromi Fuke, Masatoshi Yoshikawa, Susumu Hashimoto, Masashi Sahashi
  • Publication number: 20100118600
    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: January 12, 2010
    Publication date: May 13, 2010
    Inventors: Toshihiko NAGASE, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20100080050
    Abstract: A magnetic memory includes a magnetoresistive effect device comprising: a first ferromagnetic layer that has magnetic anisotropy in a direction perpendicular to a film plane thereof; a first nonmagnetic layer that is provided on the first ferromagnetic layer; a first reference layer that is provided on the first nonmagnetic layer, has magnetic anisotropy in a direction perpendicular to a film plane thereof, has magnetization antiparallel to a magnetization direction of the first ferromagnetic layer, and has a film thickness that is 1/5.2 to 1/1.
    Type: Application
    Filed: September 10, 2009
    Publication date: April 1, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Jyunichi OZEKI, Naoharu SHIMOMURA, Sumio IKEGAWA, Tadashi KAI, Masahiko NAKAYAMA, Hisanori AIKAWA, Tatsuya KISHI, Hiroaki YODA, Eiji KITAGAWA, Masatoshi YOSHIKAWA
  • Publication number: 20100078763
    Abstract: A resistance-change memory includes an interlayer insulating film, a lower electrode layer, a fixed layer, a first insulating film, a recording layer, a second insulating film, a conducting layer and an interconnect. The interlayer insulating film is formed on a semiconductor substrate and has a step. The lower electrode layer is formed on the interlayer insulating film including the step. The fixed layer is formed on the lower electrode layer and has invariable magnetization. The first insulating film is formed on the fixed layer. The recording layer is formed on part of the first insulating film and has variable magnetization. The second insulating film is over the recording layer and in contact with the first insulating film. The conducting layer is formed on the second insulating film. The interconnect is connected to the conducting layer.
    Type: Application
    Filed: September 14, 2009
    Publication date: April 1, 2010
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Keiji HOSOTANI, Yoshiaki ASAO, Kuniaki SUGIURA, Masatoshi YOSHIKAWA, Sumio IKEGAWA, Shigeki TAKAHASHI, Minoru AMANO
  • Patent number: 7663197
    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: September 22, 2006
    Date of Patent: February 16, 2010
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090269618
    Abstract: There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.
    Type: Application
    Filed: July 6, 2009
    Publication date: October 29, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yuuzo KAMIGUCHI, Hiromi Yuasa, Tomohiko Nagata, Hiroaki Yoda, Katsuhiko Koui, Masatoshi Yoshikawa, Hitoshi Iwasaki, Masashi Sahashi, Masayuki Takagishi
  • Publication number: 20090251951
    Abstract: A magnetoresistive element includes a foundation layer, a first magnetic layer on the foundation layer, a tunnel barrier layer on the first magnetic layer, and a second magnetic layer on the tunnel barrier layer. The first magnetic layer is made of a ferromagnetic metal containing one or more elements selected from a first group consisting of Co, Fe, and Ni, and one or more elements selected from a second group consisting of Cu, Ag, Au, Pd, Pt, Ru, Rh, Ir, and Os. The foundation layer is made of a metal containing one or more elements selected from a third group consisting of Al, Ni, Co, Fe, Mn, Cr, and V.
    Type: Application
    Filed: March 24, 2009
    Publication date: October 8, 2009
    Inventors: Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090243008
    Abstract: A magnetoresistive element includes an underlying layer having a cubic or tetragonal crystal structure oriented in a (001) plane, a first magnetic layer provided on the underlying layer, having perpendicular magnetic anisotropy, and having an fct structure oriented in a (001) plane, a non-magnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the non-magnetic layer, and having perpendicular magnetic anisotropy. An in-plane lattice constant a1 of the underlying layer and an in-plane lattice constant a2 of the first magnetic layer satisfy the following equation in which b is a magnitude of Burgers vector of the first magnetic layer, ? is an elastic modulus of the first magnetic layer, and hc is a thickness of the first magnetic layer.
    Type: Application
    Filed: March 24, 2009
    Publication date: October 1, 2009
    Inventors: Eiji Kitagawa, Masatoshi Yoshikawa, Toshihiko Nagase, Tadaomi Daibou, Makoto Nagamine, Katsuya Nishiyama, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 7596015
    Abstract: A magnetoresistive element includes a free layer which contains a magnetic material and has an fct crystal structure with a (001) plane oriented, the free layer having a magnetization which is perpendicular to a film plane and has a direction to be changeable by spin-polarized electrons, a first nonmagnetic layer and a second nonmagnetic layer which sandwich the free layer and have one of a tetragonal crystal structure and a cubic crystal structure, and a fixed layer which is provided on only one side of the free layer and on a surface of the first nonmagnetic layer opposite to a surface with the free layer and contains a magnetic material, the fixed layer having a magnetization which is perpendicular to a film plane and has a fixed direction.
    Type: Grant
    Filed: August 1, 2007
    Date of Patent: September 29, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Toshihiko Nagase, Masatoshi Yoshikawa, Katsuya Nishiyama, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090225587
    Abstract: A magnetoresistive element includes a first magnetic layer which includes a first surface and a second surface and has a first standard electrode potential, a second magnetic layer, a barrier layer which is provided between the second magnetic layer and the first surface of the first magnetic layer, and a nonmagnetic cap layer which contacts the second surface of the first magnetic layer and is formed from an alloy of a first metal material and a second metal material, the first metal material having a second standard electrode potential lower than the first standard electrode potential, the second metal material having a third standard electrode potential higher than the first standard electrode potential.
    Type: Application
    Filed: May 22, 2009
    Publication date: September 10, 2009
    Inventors: Makoto Nagamine, Toshihiko Nagase, Sumio Ikegawa, Katsuya Nishiyama, Masatoshi Yoshikawa
  • Patent number: 7564109
    Abstract: A magnetic memory device includes a first write wiring line including a wiring layer formed in a trench in an insulation layer, a barrier metal layer buried in the trench over the wiring layer. And the device includes a magneto-resistance effect element provided on the first write wiring line.
    Type: Grant
    Filed: August 13, 2004
    Date of Patent: July 21, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Takeshi Kajiyama, Hisanori Aikawa, Tomomasa Ueda, Tatsuya Kishi, Masatoshi Yoshikawa
  • Patent number: 7561383
    Abstract: There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.
    Type: Grant
    Filed: September 17, 2008
    Date of Patent: July 14, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yuuzo Kamiguchi, Hiromi Yuasa, Tomohiko Nagata, Hiroaki Yoda, Katsuhiko Koui, Masatoshi Yoshikawa, Hitoshi Iwasaki, Masashi Sahashi, Masayuki Takagishi
  • Patent number: 7515386
    Abstract: There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.
    Type: Grant
    Filed: March 27, 2006
    Date of Patent: April 7, 2009
    Assignee: Kabushiki Kaisa Toshiba
    Inventors: Yuuzo Kamiguchi, Hiromi Yuasa, Tomohiko Nagata, Hiroaki Yoda, Katsuhiko Koui, Masatoshi Yoshikawa, Hitoshi Iwasaki, Masashi Sahashi, Masayuki Takagishi
  • Patent number: 7511927
    Abstract: A spin valve type magnetoresistive effect element for vertical electric conduction includes a magnetoresistive effect film in which a resistance adjustment layer made of a material containing conductive carriers not more than 1022/cm3 is inserted. Thus the resistance value of a portion in change of spin-relied conduction is raised to an adequate value, thereby to increase the resistance variable amount.
    Type: Grant
    Filed: November 21, 2005
    Date of Patent: March 31, 2009
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiromi Yuasa, Masatoshi Yoshikawa, Katsuhiko Koui, Hitoshi Iwasaki, Masashi Sahashi
  • Publication number: 20090079018
    Abstract: A magnetoresistive element includes a first underlying layer having an NaCl structure and containing a nitride orienting in a (001) plane, a first magnetic layer provided on the first underlying layer, having magnetic anisotropy perpendicular to a film surface, having an L10 structure, and containing a ferromagnetic alloy orienting in a (001) plane, a first nonmagnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the first nonmagnetic layer and having magnetic anisotropy perpendicular to a film surface.
    Type: Application
    Filed: September 18, 2008
    Publication date: March 26, 2009
    Inventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Katsuya Nishiyama, Tadaomi Daibou, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090080238
    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: September 16, 2008
    Publication date: March 26, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi YOSHIKAWA, Eiji Kitagawa, Tadaomi Daibou, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090080124
    Abstract: A magnetoresistive element includes: a first magnetization reference layer having magnetization perpendicular to a film plane, a direction of the magnetization being invariable in one direction; a magnetization free layer having magnetization perpendicular to the film plane, a direction of the magnetization being variable; a first intermediate layer provided between the first magnetization reference layer and the magnetization free layer; a magnetic phase transition layer provided on an opposite side of the magnetization free layer from the first intermediate layer, the magnetic phase transition layer being magnetically coupled to the magnetization free layer, and being capable of bidirectionally performing a magnetic phase transition between an antiferromagnetic material and a ferromagnetic material; and an excitation layer provided on an opposite side of the magnetic phase transition layer from the magnetization free layer, and causing the magnetic phase transition layer to perform the magnetic phase transi
    Type: Application
    Filed: September 15, 2008
    Publication date: March 26, 2009
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masatoshi Yoshikawa, Tadaomi Daibou, Eiji Kitagawa, Toshihiko Nagase, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20090080239
    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: Application
    Filed: September 18, 2008
    Publication date: March 26, 2009
    Inventors: Toshihiko Nagase, Katsuya Nishiyama, Tadashi Kai, Masahiko Nakayama, Makoto Nagamine, Minoru Amano, Masatoshi Yoshikawa, Tatsuya Kishi, Hiroaki Yoda