Patents by Inventor Nobuyuki Ishiwata

Nobuyuki Ishiwata 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: 20100193889
    Abstract: A domain wall motion type MRAM 100 has: a magnetic recording layer 10 that is a ferromagnetic layer; and a magnetic coupling layer 20 that is a ferromagnetic layer whose magnetization direction is fixed. The magnetic recording layer 10 has: a first region 10-1; a second region 10-2; and a magnetization switching region 10-3 connecting between the first region 10-1 and the second region 10-2. The first region 10-1 is magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is fixed in a first direction by the magnetic coupling layer 20. The second region 10-2 is not magnetically coupled to the magnetic coupling layer 20 and its magnetization direction is a second direction that is opposite to the first direction.
    Type: Application
    Filed: July 7, 2008
    Publication date: August 5, 2010
    Inventors: Kiyokazu Nagahara, Shunsuke Fukami, Tetsuhiro Suzuki, Norikazu Ohshima, Nobuyuki Ishiwata
  • Publication number: 20100188890
    Abstract: A magnetoresistance effect element includes: a magnetization free layer; a spacer layer provided adjacent to the magnetization free layer; a first magnetization fixed layer provided adjacent to the spacer layer on a side opposite to the magnetization free layer; and at least two second magnetization fixed layers provided adjacent to the magnetization free layer. The magnetization free layer, the first magnetization fixed layer, and the second magnetization free layers respectively have magnetization components in a direction substantially perpendicular to film surfaces thereof. The magnetization free layer includes: two magnetization fixed portions; and a domain wall motion portion arranged between the two magnetization fixed portions. Magnetizations of the two magnetization fixed portions constituting the magnetization free layer are fixed substantially antiparallel to each other in directions substantially perpendicular to the film surface.
    Type: Application
    Filed: June 16, 2008
    Publication date: July 29, 2010
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata
  • Publication number: 20100149862
    Abstract: A magnetic random access memory comprises a magnetic recording layer equipped with a magnetization reversal region having a reversible magnetization and through which a write current is made to flow in the in-plane direction, a magnetization fixed layer having a fixed magnetization, a nonmagnetic layer provided between the magnetization reversal region and the magnetization fixed layer, and a heat absorbing structure provided opposing to the magnetic recording layer and having a function of receiving heat generated in the magnetic recording layer and of radiating the heat. Such magnetic random access memory can radiate heat generated in the magnetic recording layer by using the heat absorbing structure and prevent temperature rising caused by the write current flowing in the in-plane direction.
    Type: Application
    Filed: April 9, 2007
    Publication date: June 17, 2010
    Applicant: NEC CORPORATION
    Inventors: Nobuyuki Ishiwata, Hideaki Numata, Norikazu Ohshima
  • Publication number: 20100142264
    Abstract: The present invention provides a new data writing method for an MRAM which can suppress deterioration of a tunnel barrier layer. A magnetic memory cell 1 has a magnetic recording layer 10 and a pinned layer 30 connected to the magnetic recording layer 10 through a non-magnetic layer 20. The magnetic recording layer 10 includes a magnetization switching region 13, a first magnetization fixed region 11 and a second magnetization fixed region 12. The magnetization switching region 13 has reversible magnetization and faces the pinned layer 30. The first magnetization fixed region 11 is connected to a first boundary B1 of the magnetization switching region 13 and its magnetization direction is fixed to a first direction. The second magnetization fixed region 12 is connected to a second boundary B2 of the magnetization switching region 13 and its magnetization direction is fixed to a second direction.
    Type: Application
    Filed: August 4, 2006
    Publication date: June 10, 2010
    Applicant: NEC CORPORATION
    Inventors: Hideaki Numata, Norikazu Ohshima, Tetsuhiro Suzuki, Tadahiko Sugibayashi, Nobuyuki Ishiwata, Shunsuke Fukami
  • Publication number: 20100046284
    Abstract: An MRAM comprises: a plurality of magnetic memory cells each having a magnetoresistive element; and a magnetic field application section. The magnetic field application section applies an offset adjustment magnetic field in a certain direction to the plurality of magnetic memory cells from outside the plurality of magnetic memory cells. Respective data stored in the plurality of magnetic memory cells become the same when the offset adjustment magnetic field is removed.
    Type: Application
    Filed: November 12, 2007
    Publication date: February 25, 2010
    Inventors: Tadahiko Sugibayshi, Takeshi Honda, Noboru Sakimura, Nobuyuki Ishiwata, Shuichi Tahara
  • Patent number: 7372673
    Abstract: In a magnetoresistive effect transducer including a pinning layer, a pinned layer, a free layer and a non-magnetic layer inserted between the pinned layer and the free layer, a longitudinal bias layer is connected directly to a part of the free layer to apply a bias magnetic field to the free layer, thus biasing a magnetization direction of the free layer so that the magnetization direction of the free layer coincides with that of the longitudinal bias layer.
    Type: Grant
    Filed: May 31, 2005
    Date of Patent: May 13, 2008
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Keishi Ohashi, Nobuyuki Ishiwata, Masafumi Nakada, Tsutomu Ishi, Hiroaki Honjou, Kunihiko Ishihara, Jun-Ichi Fujikata, Hisao Matsutera, Hisanao Tsuge, Atsushi Kamijo
  • Patent number: 7369375
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A first magnetic layer is provided on the lower conductive layer. On the first magnetic layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: May 6, 2008
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Publication number: 20080074799
    Abstract: A magnetoresistance element includes an antiferromagnetic layer, a fixed ferromagnetic layer, a first nonmagnetic layer and a free ferromagnetic layer. The antiferromagnetic layer is formed on the upper surface side of a substrate. The fixed ferromagnetic layer is formed on the antiferromagnetic layer. The first nonmagnetic layer is formed on the fixed ferromagnetic layer. The free ferromagnetic layer is formed on the first nonmagnetic layer. The fixed ferromagnetic layer is provided with an amorphous layer. The amorphous layer contains amorphous material having a composition expressed by a chemical formula of X—Y-Z. X is an element selected from Co, Fe and Ni. Y is an element selected from Al, Si, Mg, Ta, Nb, Zr, Hf, W, Mo, Ti and V. Z is an element selected from N, C and B.
    Type: Application
    Filed: June 30, 2005
    Publication date: March 27, 2008
    Inventor: Nobuyuki Ishiwata
  • Publication number: 20080008908
    Abstract: A ferromagnetic film according to the present invention includes ferromagnetic element and nonmagnetic element and has a first portion and a second portion. Concentration of the nonmagnetic element in the first portion is lower than an average concentration of the nonmagnetic element in the ferromagnetic film. On the other hand, concentration of the nonmagnetic element in the second portion is higher than the average concentration of the nonmagnetic element in the ferromagnetic film. The nonmagnetic element includes at least one element selected from the group consisting of Zr, Ti, Nb, Ta, Hf, Mo and W. The ferromagnetic film is applied to a magnetic free layer of a magneto-resistance element in an MRAM.
    Type: Application
    Filed: November 9, 2005
    Publication date: January 10, 2008
    Applicant: NEC CORPORATION
    Inventors: Nobuyuki Ishiwata, Hiroaki Honjo, Katsuya Nishiyama, Toshihiko Nagase
  • Patent number: 7298596
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: November 20, 2007
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 7277261
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. Furthermore, an upper conductive layer is provided on the upper layer and an insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: October 2, 2007
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kivokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 7265949
    Abstract: A magneto-resistance effect element is adapted that a non-magnetic layer (9, 18), a free layer (3b, 19), another non-magnetic layer (4, 25), a fixed layer (5, 26), and a fixing layer (6b, 27) are formed vertically symmetric with respect to a first magnetic layer (8b), to which a vertical bias magnetic field is applied from an underlying layer (2a) for a vertical bias layer (2b). The magneto-resistance effect element operates in CPP mode. Generally, the free layer is unavoidably subjected to the influence of a circular electric magnetic field caused by a current flowing perpendicularly to the film surface. However, in the magneto-resistance effect element, the influence of the electric magnetic field to which the free layer (3b) is subjected is opposite to that of the electric magnetic field to which the second free layer (19) is subjected, thereby canceling out the influences as a hole.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: September 4, 2007
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 7239482
    Abstract: A thin-film magnetic head is constituted by forming a lower shielding layer, a read gap layer holding an MR magnetosensitive element, a common pole layer, and a write gap layer in order on an insulating substrate, forming a first flattening layer, a coil pattern layer, and a second flattening layer laminated in order on the write gap layer excluding the vicinity of an ABS plane, and forming an upper pole layer on the write gap layer and the second flattening layer nearby an ABS plane. A concave portion is formed on the common pole layer at a position separated from the ABS plane, the concave portion is filled with a nonmagnetic body, and the gap depth between the upper pole layer and the common pole layer is determined by the concave portion.
    Type: Grant
    Filed: January 18, 2006
    Date of Patent: July 3, 2007
    Assignee: TDK Corporation
    Inventors: Shinsaku Saitho, Haruo Urai, Nobuyuki Ishiwata, Kiyotaka Shimabayashi, Yoshihiro Nonaka, Tamaki Toba
  • Patent number: 7230794
    Abstract: A thin-film magnetic head is constituted by forming a lower shielding layer, a read gap layer holding an MR magnetosensitive element, a common pole layer, and a write gap layer in order on an insulating substrate, forming a first flattening layer, a coil pattern layer, and a second flattening layer laminated in order on the write gap layer excluding the vicinity of an ABS plane, and forming an upper pole layer on the write gap layer and the second flattening layer nearby an ABS plane. A concave portion is formed on the common pole layer at a position separated from the ABS plane, the concave portion is filled with a nonmagnetic body, and the gap depth between the upper pole layer and the common pole layer is determined by the concave portion.
    Type: Grant
    Filed: March 24, 2006
    Date of Patent: June 12, 2007
    Assignee: TDK Corporation
    Inventors: Shinsaku Saitho, Haruo Urai, Nobuyuki Ishiwata, Kiyotaka Shimabayashi, Yoshihiro Nonaka, Tamaki Toba
  • Publication number: 20070047158
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: June 30, 2006
    Publication date: March 1, 2007
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 7173793
    Abstract: A recording head is a magnetic head in which ends on one side of opposed first and second magnetic cores form a recording gap, said other ends form a magnetic joint, coils insulated by an insulating material are provided between said first and second magnetic cores, magnetic fluxes of said first and second magnetic cores excited by said coils leak from said recording gap so that recording onto a recording medium is carried out. In said recording head, a distance from said end of said recording gap close to said magnetic medium to a contact point of said magnetic joint (hereinafter, yoke length) is not more than 20 ?m. A magnetic recording/reproduction apparatus has this head.
    Type: Grant
    Filed: August 5, 2004
    Date of Patent: February 6, 2007
    Assignee: NEC Corporation
    Inventors: Nobuyuki Ishiwata, Hiroaki Honjo, Tamaki Toba, Shinsaku Saito, Yoshihiro Nonaka, Tsutomu Ishi, Mikiko Saito, Keishi Ohashi
  • Patent number: 7161774
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Grant
    Filed: March 16, 2006
    Date of Patent: January 9, 2007
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Patent number: 7158355
    Abstract: A magneto-resistance effect element is provided and includes a lower conductive layer, a pattern provided thereon and made up of a fixed layer having a pinned orientation of magnetization, a first non-magnetic layer provided on the fixed layer, a free layer provided on the non-magnetic layer and having an orientation of magnetization varied by a magnetic field applied thereto, a first magnetic layer provided on the free layer; and a vertical bias layer, provided on the first magnetic layer, for applying a magnetic field to the first magnetic layer, and a sense current for detecting a change in electrical resistance of the non-magnetic layer flows substantially in perpendicular relation to the non-magnetic layer. The pattern is buried in an insulation layer with the vertical bias layer of the pattern being exposed on an upper surface of the insulation layer.
    Type: Grant
    Filed: September 16, 2005
    Date of Patent: January 2, 2007
    Assignee: NEC Corporation
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Publication number: 20060274456
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: June 30, 2006
    Publication date: December 7, 2006
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata
  • Publication number: 20060268466
    Abstract: A magneto-resistance effect head is provided with a lower conductive layer which is provided with a recessed portion, and a vertical bias layer is provided in the recessed portion. A free layer is provided on the lower conductive layer. On the free layer, layered in the following order are the non-magnetic layer, the fixed layer, the fixing layer, and the upper layer so as not to be placed immediately above the vertical bias layer. The non-magnetic layer, the fixed layer, the fixing layer, and the upper layer are buried in an insulation layer. Furthermore, an upper conductive layer is provided on the upper layer and the insulation layer. In the direction of the magnetic field applied by the vertical bias layer, the free layer is made greater in length than the fixed layer and the free layer is disposed in proximity to the vertical bias layer with the distance between the fixed layer and the vertical bias layer remaining unchanged.
    Type: Application
    Filed: June 30, 2006
    Publication date: November 30, 2006
    Inventors: Kazuhiko Hayashi, Junichi Fujikata, Tsutomu Ishi, Shigeru Mori, Keishi Ohashi, Masafumi Nakada, Kiyokazu Nagahara, Kunihiko Ishihara, Nobuyuki Ishiwata