Patents by Inventor Masahiko Nakayama

Masahiko Nakayama 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: 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: 20140264669
    Abstract: A magnetic memory element includes a memory layer having magnetic anisotropy on the film surface thereof in the perpendicular direction and in which the magnetization direction is variable, a reference layer having magnetic anisotropy on the film surface thereof in the perpendicular direction and in which the magnetization direction is not variable, and a tunnel barrier layer which is interposed between the memory layer and the reference layer. The memory layer is made of an alloy including cobalt (Co) andiron (Fe). A plurality of oxygen atoms are present on both interfaces of the memory layer.
    Type: Application
    Filed: September 3, 2013
    Publication date: September 18, 2014
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Masahiko NAKAYAMA, Tatsuya KISHI, Masaru TOKO, Akiyuki MURAYAMA, Yutaka HASHIMOTO, Hisanori AIKAWA
  • Publication number: 20140070343
    Abstract: A magnetoresistive effect element in one or more embodiments of the present invention is provided with a memory layer with a variable magnetization direction having a magnetic anisotropy in a direction perpendicular to a film surface, a reference layer with an invariable magnetization direction having the magnetic anisotropy in a direction perpendicular to the film surface, and a tunnel barrier layer formed between the memory layer and the reference layer. The tunnel barrier layer has a first portion at the central part in the film surface and a second portion at a peripheral part. The second portion contains at least boron and oxygen.
    Type: Application
    Filed: February 26, 2013
    Publication date: March 13, 2014
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Shigeto FUKATSU, Tatsuya KISHI, Masahiko NAKAYAMA, Akiyuki MURAYAMA
  • 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: 20130313506
    Abstract: A magnetoresistive element has a magnetic layer, an insulating layer and a magnetic layer, which are laminated on a base electrode, and side walls of the magnetic layers that are formed when the magnetic layers are processed. At least one element selected from the group of consisting He, C, N, O, F, Ne, Ti, V, Cu, Al, Si, P, S, Cl, Ar, Ge, As, Kr, Zr, In, Sn, Sb, Pb and Bi is injected into the side walls and edge portions of the magnetic layers to improve the magnetic characteristics of the first and second magnetic layers.
    Type: Application
    Filed: February 26, 2013
    Publication date: November 28, 2013
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Akiyuki MURAYAMA, Masahiko NAKAYAMA, Satoshi SETO, Tatsuya KISHI, Masaru TOKO
  • Patent number: 8553450
    Abstract: A first magnetic layer has a magnetization fixed along one direction. A first nonmagnetic layer on the first magnetic layer functions as a first tunnel barrier. A second magnetic layer on the first nonmagnetic layer has a magnetization whose direction can be reversed by spin transfer current injection. A second nonmagnetic layer on the second magnetic layer functions as a second tunnel barrier. A third magnetic layer on the second nonmagnetic layer has a magnetization whose direction can be reversed by spin transfer through current injection at a current density different from the second magnetic layer. First magnetic, first nonmagnetic layer, and second magnetic layers exhibit a first magnetoresistive effect. Second magnetic, second nonmagnetic, and third magnetic layers exhibit a second magnetoresistive effect. A magnetoresistive effect element records and reads out data of at least three levels based on a synthetic resistance from the first and second magnetoresistive effects.
    Type: Grant
    Filed: July 27, 2009
    Date of Patent: October 8, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Keiji Hosotani, Masahiko Nakayama
  • 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
  • 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: 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: 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
  • 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
  • Patent number: 8363462
    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 15, 2011
    Date of Patent: January 29, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
  • Patent number: 8349622
    Abstract: A magneto-resistive element according to an aspect of the present invention includes a free layer whose magnetized state changes and a pinned layer whose magnetized state is fixed. The free layer comprises first and second ferromagnetic layers and a non-magnetic layer which is arranged between the first and second ferromagnetic layers. An intensity of exchange coupling between the first and second ferromagnetic layers is set so that an astroid curve in a hard axis direction opens.
    Type: Grant
    Filed: January 29, 2009
    Date of Patent: January 8, 2013
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Sumio Ikegawa, Masahiko Nakayama, Tadashi Kai, Eiji Kitagawa, Hiroaki Yoda
  • Patent number: 8279663
    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: Grant
    Filed: July 18, 2011
    Date of Patent: October 2, 2012
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masahiko Nakayama, Tadashi Kai, Sumio Ikegawa, Hiroaki Yoda, Tatsuya Kishi