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).

  • 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: 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
  • Publication number: 20140035073
    Abstract: A magneto-resistive element has a memory layer, which has magnetic anisotropy along a direction perpendicular to its surface and variable magnetization directions, a reference layer, which has magnetic anisotropy along a direction perpendicular to its surface and a fixed magnetization direction, and a tunnel barrier layer, which is formed between the memory layer and the reference layer. The memory layer is composed of Co1-xFexB, where 0.4?x<0.6 and the thickness is 0.7 nm or more but less than 1.0 nm; or where 0.6?x<0.8 and the thickness is 0.7 nm or more but less than 1.1 nm; or where 0.8?x<1.0 and the thickness is 0.9 nm or more but less than 1.2 nm.
    Type: Application
    Filed: February 26, 2013
    Publication date: February 6, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Masaru TOKO, Tatsuya Kishi, Masahiko Nakayama, Hiroaki Yoda
  • Patent number: 8634238
    Abstract: According to one embodiment, a magnetic memory element includes a memory layer, a first nonmagnetic layer, a reference layer, a second nonmagnetic layer, and an adjustment layer which are stacked. The adjustment layer is configured to reduce a leakage magnetic field from the reference layer. The adjustment layer is formed by stacking an interface layer provided on the second nonmagnetic layer, and a magnetic layer having magnetic anisotropy perpendicular to a film surface. Saturation magnetization of the interface layer is larger than that of the magnetic layer.
    Type: Grant
    Filed: September 5, 2012
    Date of Patent: January 21, 2014
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Hisanori Aikawa, Masaru Toko, Hiroaki Yoda, Tatsuya Kishi, Sumio Ikegawa
  • Publication number: 20130288397
    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: July 1, 2013
    Publication date: October 31, 2013
    Inventors: Eiji Kitagawa, Tadaomi Daibou, Yutaka Hashimoto, Masaru Tokou, Tadashi Kai, Makato Nagamine, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
  • Patent number: 8547737
    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: Grant
    Filed: September 27, 2012
    Date of Patent: October 1, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Tadaomi Daibou, Eiji Kitagawa, Yutaka Hashimoto, Masaru Tokou, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Makoto Nagamine, Tadashi Kai, Hiroaki Yoda
  • Patent number: 8530887
    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: Grant
    Filed: March 17, 2011
    Date of Patent: September 10, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Eiji Kitagawa, Tadashi Kai, Tadaomi Daibou, Yutaka Hashimoto, Hiroaki Yoda
  • Patent number: 8530987
    Abstract: A magnetic memory includes a magnetoresistive element. The magnetoresistive element includes a reference layer having an invariable magnetization direction, a storage layer having a variable magnetization direction, and a spacer layer provided between the reference layer and the storage layer. The storage layer has a multilayered structure including first and second magnetic layers, the second magnetic layer is provided between the first magnetic layer and the spacer layer and has a magnetic anisotropy energy lower than that of the first magnetic layer, and an exchange coupling constant Jex between the first magnetic layer and the second magnetic layer is not more than 5 erg/cm2.
    Type: Grant
    Filed: March 28, 2012
    Date of Patent: September 10, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hisanori Aikawa, Tadashi Kai, Masahiko Nakayama, Sumio Ikegawa, Naoharu Shimomura, Eiji Kitagawa, Tatsuya Kishi, Jyunichi Ozeki, Hiroaki Yoda, Satoshi Yanagi
  • Patent number: 8531875
    Abstract: According to one embodiment, a magnetic memory includes at least one memory cell including a magnetoresistive element, and first and second electrodes. The element includes a first magnetic layer, a tunnel barrier layer, a second magnetic layer, and a third magnetic layer provided on the second magnetic layer and having a magnetization antiparallel to the magnetization direction of the second magnetic layer. A diameter of an upper surface of the first magnetic layer is smaller than that of a lower surface of the tunnel barrier layer. A diameter of a lower surface of the second magnetic layer is not more than that of an upper surface of the tunnel barrier layer.
    Type: Grant
    Filed: March 21, 2012
    Date of Patent: September 10, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Satoshi Yanagi, Eiji Kitagawa, Masahiko Nakayama, Jyunichi Ozeki, Hisanori Aikawa, Naoharu Shimomura, Masatoshi Yoshikawa, Minoru Amano, Shigeki Takahashi, Hiroaki Yoda
  • Patent number: 8502331
    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: Grant
    Filed: September 16, 2011
    Date of Patent: August 6, 2013
    Assignee: 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
  • Publication number: 20130099337
    Abstract: According to one embodiment, a magnetic memory element includes a memory layer, a first nonmagnetic layer, a reference layer, a second nonmagnetic layer, and an adjustment layer which are stacked. The adjustment layer is configured to reduce a leakage magnetic field from the reference layer. The adjustment layer is formed by stacking an interface layer provided on the second nonmagnetic layer, and a magnetic layer having magnetic anisotropy perpendicular to a film surface. Saturation magnetization of the interface layer is larger than that of the magnetic layer.
    Type: Application
    Filed: September 5, 2012
    Publication date: April 25, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Hisanori Aikawa, Masaru Toko, Hiroaki Yoda, Tatsuya Kishi, Sumio Ikegawa
  • Publication number: 20130099338
    Abstract: According to one embodiment, a magnetic memory element includes a memory layer having magnetic anisotropy perpendicular to a film surface and having a variable magnetization direction, a first nonmagnetic layer provided on the memory layer, and a reference layer provided on the first nonmagnetic layer, having magnetic anisotropy perpendicular to a film surface, and having an invariable magnetization direction. An area of the memory layer is larger than that of the reference layer. Magnetization in an end portion of the memory layer is smaller than that in a central portion of the memory layer.
    Type: Application
    Filed: September 5, 2012
    Publication date: April 25, 2013
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masahiko Nakayama, Tatsuya Kishi, Hiroaki Yoda, Hisanori Aikawa, Masaru Toko
  • Publication number: 20130077388
    Abstract: One embodiment provides a magnetic memory element, including: a first ferromagnetic layer whose magnetization is variable; a second ferromagnetic layer which has a first band split into a valence band and a conduction band and a second band being continuous at least from the valence band to the conduction band; and a nonmagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer.
    Type: Application
    Filed: June 26, 2012
    Publication date: March 28, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Tomoaki Inokuchi, Takao Marukame, Mizue Ishikawa, Hideyuki Sugiyama, Masahiko Nakayama, Tatsuya Kishi, Hiroaki Yoda, Yoshiaki Saito
  • Publication number: 20130069185
    Abstract: According to one embodiment, a magnetic memory element includes a stacked body including first and second stacked units stacked with each other. The first stacked unit includes first and second ferromagnetic layers and a first nonmagnetic layer provided therebetween. The second stacked unit includes third and fourth ferromagnetic layers and a second nonmagnetic layer provided therebetween. Magnetization of the second and third ferromagnetic layers are variable. Magnetizations of the first and fourth ferromagnetic layers are fixed in a direction perpendicular to the layer surfaces. A cross-sectional area of the third ferromagnetic layer is smaller than a cross-sectional area of the first stacked unit when cut along a plane perpendicular to the stacking direction.
    Type: Application
    Filed: March 9, 2012
    Publication date: March 21, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Daisuke SAIDA, Minoru Amano, Yuichi Ohsawa, Junichi Ito, Hiroaki Yoda
  • Publication number: 20130069184
    Abstract: According to one embodiment, a magnetoresistive element comprises a first magnetic layer, in which a magnetization direction is variable and is perpendicular to a film surface, a tunnel barrier layer that is formed on the first magnetic layer, and a second magnetic layer that is formed on the tunnel barrier layer, a magnetization direction of the second magnetic layer being variable and being perpendicular to the film surface. The second magnetic layer comprises a body layer that constitutes an origin of perpendicular magnetic anisotropy, and an interface layer that is formed between the body layer and the tunnel barrier layer. The interface layer has a permeability higher than that of the body layer and a planar size larger than that of the body layer.
    Type: Application
    Filed: September 14, 2012
    Publication date: March 21, 2013
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Hisanori AIKAWA, Hiroaki YODA, Masahiko NAKAYAMA, Tatsuya KISHI, Sumio IKEGAWA
  • Publication number: 20130069186
    Abstract: According to one embodiment, a magnetoresistive element comprises a first magnetic layer having a magnetization direction invariable and perpendicular to a film surface, a tunnel barrier layer formed on the first magnetic layer, and a second magnetic layer formed on the tunnel barrier layer and having a magnetization direction variable and perpendicular to the film surface. The first magnetic layer includes an interface layer formed on an upper side in contact with a lower portion of the tunnel barrier layer, and a main body layer formed on a lower side and serving as an origin of perpendicular magnetic anisotropy. The interface layer includes a first area provided on an inner side and having magnetization, and a second area provided on an outer side to surround the first area and having magnetization smaller than the magnetization of the first area or no magnetization.
    Type: Application
    Filed: September 14, 2012
    Publication date: March 21, 2013
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masaru TOKO, Masahiko NAKAYAMA, Akihiro NITAYAMA, Tatsuya KISHI, Hisanori AIKAWA, Hiroaki YODA
  • Publication number: 20130056349
    Abstract: Provided are a sputtering target including a target main body 10 that has MgO as a main component and a thickness of 3 mm or smaller, and a method of manufacturing a magnetic memory using the sputtering target which improves an MR ratio.
    Type: Application
    Filed: August 31, 2012
    Publication date: March 7, 2013
    Inventors: Eiji KITAGAWA, Tadaomi DAIBOU, Kenji NOMA, Tadashi KAI, Koji YAMAKAWA, Toshihiko NAGASE, Katsuya NISHIYAMA, Koji UEDA, Daisuke WATANABE, Hiroaki YODA, Satoru SANO, Yoshihiro NISHIMURA, Takayuki WATANABE, Yuzo KATO, Akira UEKI
  • Patent number: 8378437
    Abstract: A magnetoresistive effect element includes a reference layer, a recording layer, and a nonmagnetic layer. The reference layer is made of a magnetic material, has an invariable magnetization which is perpendicular to a film surface. The recording layer is made of a magnetic material, has a variable magnetization which is perpendicular to the film surface. The nonmagnetic layer is arranged between the reference layer and the recording layer. A critical diameter which is determined by magnetic anisotropy, saturation magnetization, and switched connection of the recording layer and has a single-domain state as a unique stable state or a critical diameter which has a single-domain state as a unique stable state and is inverted while keeping the single-domain state in an inverting process is larger than an element diameter of the magnetoresistive effect element.
    Type: Grant
    Filed: October 9, 2008
    Date of Patent: February 19, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Kay Yakushiji, Sumio Ikegawa, Shinji Yuasa, Tadashi Kai, Toshihiko Nagase, Minoru Amano, Hisanori Aikawa, Tatsuya Kishi, Hiroaki Yoda
  • Publication number: 20130028011
    Abstract: A magnetoresistive device of an embodiment includes: first and second devices each including, a first magnetic layer having a changeable magnetization perpendicular to a film plane, a second magnetic layer having a fixed and perpendicular magnetization, and a nonmagnetic layer interposed between the first and second magnetic layers, the first and second devices being disposed in parallel on a first face of an interconnect layer; and a TMR device including a third magnetic layer having perpendicular magnetic anisotropy and having a changeable magnetization, a fourth magnetic layer having a fixed magnetization parallel to a film plane, and a tunnel barrier layer interposed between the third and fourth magnetic layers, the TMR device being disposed on a second face of the interconnect layer, and the third magnetic layer being magnetostatically coupled to the first magnetic layers of the first and second devices.
    Type: Application
    Filed: March 20, 2012
    Publication date: January 31, 2013
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Eiji KITAGAWA, Naoharu SHIMOMURA, Hiroaki Yoda, Junichi ITO, Minoru AMANO, Chikayoshi KAMATA, Keiko ABE
  • Publication number: 20130029431
    Abstract: According to one embodiment, a method for manufacturing a nonvolatile memory device including a plurality of memory cells is disclosed. Each of the plurality of memory cells includes a base layer including a first electrode, a magnetic tunnel junction device provided on the base layer, and a second electrode provided on the magnetic tunnel junction device. The magnetic tunnel junction device includes a first magnetic layer, a tunneling barrier layer provided on the first magnetic layer, and a second magnetic layer provided on the tunneling barrier layer. The method can include etching a portion of the second magnetic layer and a portion of the first magnetic layer by irradiating gas clusters onto a portion of a surface of the second magnetic layer or a portion of a surface of the first magnetic layer.
    Type: Application
    Filed: June 27, 2012
    Publication date: January 31, 2013
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Shigeki TAKAHASHI, Kyoichi SUGURO, Junichi ITO, Yuichi OHSAWA, Hiroaki YODA