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: 20110267879
    Abstract: A magnetic memory cell includes: a magnetization recording layer; and a magnetic tunneling junction section. The magnetization recording layer includes a ferromagnetic layer with perpendicular magnetic anisotropy. The magnetic tunneling junction section is used for reading information in the magnetization recording layer. The magnetization recording layer includes two domain wall moving areas.
    Type: Application
    Filed: December 24, 2009
    Publication date: November 3, 2011
    Applicant: NEC CORPORATION
    Inventors: Kiyokazu Nagahara, Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima
  • Publication number: 20110260273
    Abstract: A magnetic memory cell is provided with a magnetization record layer and a magnetic tunnel junction section. The magnetization record layer is a ferromagnetic layer having a perpendicular magnetic anisotropy. The magnetic tunnel junction section is used to read data from the magnetization record layer. The magnetization record layer has a plurality of domain wall motion regions.
    Type: Application
    Filed: December 24, 2009
    Publication date: October 27, 2011
    Inventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki, Nobuyuki Ishiwata, Norikazu Ohshima
  • Patent number: 8040724
    Abstract: A magnetic random access memory includes: a magnetic recording layer including a ferromagnetic layer and having perpendicular magnetic anisotropy; and a magnetic reading layer provided on the magnetic recording layer and used for reading information. The magnetic recording layer includes: a magnetization switching area having reversible magnetization; a first magnetization pinned area connected to a first boundary of the magnetization switching area and having magnetization whose direction is pinned in a first direction; and a second magnetization pinned area connected to a second boundary of the magnetization switching area and having magnetization whose direction is pinned in a second direction. The magnetic reading layer includes: a magnetic sensing layer whose direction of magnetization changes based on a direction of the magnetization of the magnetization switching area; a nonmagnetic barrier layer provided on the magnetic sensing layer; and a pinned layer provided on the nonmagnetic barrier layer.
    Type: Grant
    Filed: July 7, 2008
    Date of Patent: October 18, 2011
    Assignee: NEC Corporation
    Inventors: Tetsuhiro Suzuki, Norikazu Ohshima, Shunsuke Fukami, Kiyokazu Nagahara, Nobuyuki Ishiwata
  • Publication number: 20110199818
    Abstract: An initialization method is provided for a magnetic memory element including: a data recording layer having perpendicular magnetic anisotropy which includes: a first magnetization fixed region, a second magnetization fixed region, and a magnetization free region coupled to the first magnetization fixed region and the second magnetization fixed region, the data recording layer being structure so that the coercive force of the first magnetization fixed region being different from that of the second magnetization fixed region. The initialization method includes steps of: directing the magnetizations of the first magnetization fixed region, the second magnetization fixed region and the magnetization free region in the same direction; and applying a magnetic field having both components perpendicular to and parallel to the magnetic anisotropy of the data recording layer to the data recording layer.
    Type: Application
    Filed: October 29, 2009
    Publication date: August 18, 2011
    Inventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki, Nobuyuki Ishiwata, Norikazu Ohsima
  • Publication number: 20110188298
    Abstract: A magnetoresistance element is provided with: a magnetization recording layer that is a ferromagnetic layer. The magnetization recording layer includes: a magnetization reversal region having a reversible magnetization; a first magnetization fixed region connected to a first boundary of the magnetization reversal region and having a magnetization direction fixed in a first direction; and a second magnetization fixed region connected to a second boundary of the magnetization reversal region and having a magnetization direction fixed in a second direction. At least one magnetization reversal facilitation structure which is a structure in which a magnetization is reversed more easily than the remaining portion is provided for a portion of the second magnetization fixed region.
    Type: Application
    Filed: October 16, 2009
    Publication date: August 4, 2011
    Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
  • Publication number: 20110163402
    Abstract: A magnetic memory according to the present invention has: a first underlayer; a second underlayer so formed on the first underlayer as to be in contact with the first underlayer; and a data storage layer so formed on the second underlayer as to be in contact with the second underlayer. The data storage layer is made of a ferromagnetic material having perpendicular magnetic anisotropy. A magnetization state of the data storage layer is changed by current driven domain wall motion.
    Type: Application
    Filed: August 13, 2009
    Publication date: July 7, 2011
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Oshima
  • Publication number: 20110157967
    Abstract: A magnetic memory includes a magnetization recording layer, a first terminal, a second terminal, a magnetization pinned layer and a non-magnetic layer. The magnetization recording layer has a vertical magnetic anisotropy and includes a ferromagnetic layer. The first terminal is connected to one end of a first region in the magnetization recording layer. The second terminal is connected to the other end of the first region. The non-magnetic layer is arranged on the first region. The magnetization pinned layer is arranged on the non-magnetic layer and is located on the side opposite to the first region. The magnetization recording layer includes: a first extension portion located outside the first terminal in the magnetization recording layer; and a property changing structure that is arranged in the first extension portion and substantially changes a magnetization switching property of the magnetization recording layer.
    Type: Application
    Filed: June 26, 2009
    Publication date: June 30, 2011
    Applicant: NEC Corporation
    Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
  • Publication number: 20110129691
    Abstract: A domain wall motion element has a magnetic recording layer 10 that is formed of a ferromagnetic film and has a domain wall DW. The magnetic recording layer 10 has: a pair of end regions 11-1 and 11-2 whose magnetization directions are fixed; and a center region 12 sandwiched between the pair of end regions 11-1 and 11-2, in which the domain wall. DW moves. A first trapping site TS1 by which the domain wall DW is trapped is formed at a boundary between the end region 11-1, 11-2 and the center region 12. Furthermore, at least one second trapping site TS2 by which the domain wall DW is trapped is formed within the center region 12.
    Type: Application
    Filed: January 13, 2009
    Publication date: June 2, 2011
    Inventors: Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara, Shunsuke Fukami
  • Patent number: 7948783
    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: Grant
    Filed: November 12, 2007
    Date of Patent: May 24, 2011
    Assignee: NEC Corporation
    Inventors: Tadahiko Sugibayashi, Takeshi Honda, Noboru Sakimura, Nobuyuki Ishiwata, Shuichi Tahara
  • Publication number: 20110116306
    Abstract: A domain wall motion type MRAM has: a magnetic recording layer 10 being a ferromagnetic layer having perpendicular magnetic anisotropy; a pair of current supply terminals 14a and 14b connected to the magnetic recording layer 10 for supplying a current to the magnetic recording layer 10; and an anti-ferromagnetic layer 45 being in contact with a first region R1 of the magnetic recording layer 10. The first region R1 includes a part of a current supply region RA of the magnetic recording layer 10 that is between the pair of current supply terminals 14a and 14b.
    Type: Application
    Filed: July 2, 2009
    Publication date: May 19, 2011
    Applicant: NEC CORPORATION
    Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Oshima, Nobuyuki Ishiwata
  • Patent number: 7929342
    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: Grant
    Filed: August 4, 2006
    Date of Patent: April 19, 2011
    Assignee: NEC Corporation
    Inventors: Hideaki Numata, Norikazu Ohshima, Tetsuhiro Suzuki, Tadahiko Sugibayashi, Nobuyuki Ishiwata, Shunsuke Fukami
  • Publication number: 20110002163
    Abstract: A semiconductor device includes: a first magnetic random access memory including a first memory cell and a second magnetic random access memory including a second memory cell operating at higher speed than the first memory cell and is provided on the same chip together with the first magnetic random access memory. The first memory cell is a current-induced domain wall motion type MRAM and stores data based on a domain wall position of a magnetization free layer. A layer that a write current flows is different from a layer that a read current flows. The second memory cell is a current-induced magnetic field writing type MRAM and stores data based on a magnetic field induced by a write current.
    Type: Application
    Filed: March 5, 2009
    Publication date: January 6, 2011
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
  • Patent number: 7855860
    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—N. X is an element selected from Co, Fe and Ni. Y is an element selected from AI, Si, Mg, Ta, Nb, Zr, Hf, W, Mo, Ti and V. N represents nitrogen.
    Type: Grant
    Filed: June 30, 2005
    Date of Patent: December 21, 2010
    Assignee: NEC Corporation
    Inventor: Nobuyuki Ishiwata
  • Publication number: 20100315854
    Abstract: A domain wall motion type MRAM has: a magnetic recording layer 10 having perpendicular magnetic anisotropy; and a pair of terminals 51 and 52 used for supplying a current to the magnetic recording layer 10. The magnetic recording layer 10 has: a first magnetization region 11 connected to one of the pair of terminals; a second magnetization region 12 connected to the other of the pair of terminals; and a magnetization switching region 13 connecting between the first magnetization region 11 and the second magnetization region 12 and having reversible magnetization. A first pinning site PS1, by which the domain wall is trapped, is formed at a boundary between the first magnetization region 11 and the magnetization switching region 13. A second pinning site PS2, by which the domain wall is trapped, is formed at a boundary between the second magnetization region 12 and the magnetization switching region 13.
    Type: Application
    Filed: December 10, 2008
    Publication date: December 16, 2010
    Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Norikazu Ohshima, Kiyokazu Nagahara, Nobuyuki Ishiwata
  • Publication number: 20100309713
    Abstract: An MRAM has: a memory cell including a first magnetoresistance element; and a reference cell including a second magnetoresistance element. The first magnetoresistance element has a first magnetization fixed layer, a first magnetization free layer, a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the first magnetization free layer, a second magnetization fixed layer, a second magnetization free layer and a second nonmagnetic layer sandwiched between the second magnetization fixed layer and the second magnetization free layer. The first magnetization fixed layer and the first magnetization free layer have perpendicular magnetic anisotropy, and the second magnetization fixed layer and the second magnetization free layer have in-plane magnetic anisotropy. The first magnetization free layer and the second magnetization free layer are magnetically coupled to each other.
    Type: Application
    Filed: January 9, 2009
    Publication date: December 9, 2010
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
  • Publication number: 20100309712
    Abstract: An MRAM has: a memory cell including a first magnetoresistance element; and a reference cell including a second magnetoresistance element. The first magnetoresistance element has a first magnetization free layer, a first magnetization fixed layer, a second magnetization free layer and a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the second magnetization free layer. The first magnetization free layer has perpendicular magnetic anisotropy, and the first magnetization fixed layer and the second magnetization free layer has in-plane magnetic anisotropy. The first magnetization free layer has: first and second magnetization fixed regions whose magnetization directions are fixed; and a magnetization free region whose magnetization direction is reversible and connected to the first and second magnetization fixed regions. The magnetization free region and the second magnetization free layer are magnetically coupled to each other.
    Type: Application
    Filed: January 9, 2009
    Publication date: December 9, 2010
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
  • Publication number: 20100254183
    Abstract: A magnetoresistance effect element has: a first magnetization fixed layer whose magnetization direction is fixed; a first magnetization free layer whose magnetization direction is variable; a first nonmagnetic layer sandwiched between the first magnetization fixed layer and the first magnetization free layer; a second magnetization fixed layer whose magnetization direction is fixed; a second magnetization free layer whose magnetization direction is variable; and a second nonmagnetic layer sandwiched between the second magnetization fixed layer and the second magnetization free layer. The first magnetization fixed layer and the first magnetization free layer have perpendicular magnetic anisotropy, while the second magnetization fixed layer and the second magnetization free layer have in-plane magnetic anisotropy. The first magnetization free layer and the second magnetization free layer are magnetically coupled to each other.
    Type: Application
    Filed: August 21, 2008
    Publication date: October 7, 2010
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
  • Publication number: 20100237449
    Abstract: A magnetoresistive element is provided with a first magnetization free layer; a second magnetization free layer; a non-magnetic layer disposed adjacent to the second magnetization free layer; and a first magnetization fixed layer disposed adjacent to the second magnetization free layer on an opposite side of the second magnetization free layer. The first magnetization free layer is formed of ferromagnetic material and has a magnetic anisotropy in a thickness direction. On the other hand, the second magnetization free layer and the first magnetization fixed layer are formed of ferromagnetic material and have a magnetic anisotropy in an in-plane direction. The first magnetization free layer includes: a first magnetization fixed region having a fixed magnetization; a second magnetization fixed region having a fixed magnetization; and a magnetization free region connected to the first and second magnetization fixed regions and having a reversible magnetization.
    Type: Application
    Filed: October 28, 2008
    Publication date: September 23, 2010
    Inventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima
  • Publication number: 20100214826
    Abstract: A magnetic random access memory includes: a first ferromagnetic layet; an insulating layer provided adjacent to the first ferromagnetic layer; and a first magnetization pinned layer provided adjacent to the insulating layer on a side opposite to the first ferromagnetic layer. The first ferromagnetic layer includes a magnetization free region, a first magnetization pinned region, and a second magnetization pinned region. The magnetization free region has reversible magnetization, and overlaps with the second ferromagnetic layer. The first magnetization pinned region has first pinned magnetization, and is connected to a part of the magnetization free region. The second magnetization pinned region has second pinned magnetization, and is connected to a part of the magnetization free region. The first ferromagnetic layer has magnetic anisotropy in a direction perpendicular to a film surface.
    Type: Application
    Filed: July 7, 2008
    Publication date: August 26, 2010
    Applicant: NEC CORPORATION
    Inventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
  • Publication number: 20100193890
    Abstract: A magnetic random access memory includes: a magnetic recording layer including a ferromagnetic layer and having perpendicular magnetic anisotropy; and a magnetic reading layer provided on the magnetic recording layer and used for reading information. The magnetic recording layer includes: a magnetization switching area having reversible magnetization; a first magnetization pinned area connected to a first boundary of the magnetization switching area and having magnetization whose direction is pinned in a first direction; and a second magnetization pinned area connected to a second boundary of the magnetization switching area and having magnetization whose direction is pinned in a second direction. The magnetic reading layer includes: a magnetic sensing layer whose direction of magnetization changes based on a direction of the magnetization of the magnetization switching area; a nonmagnetic barrier layer provided on the magnetic sensing layer; and a pinned layer provided on the nonmagnetic barrier layer.
    Type: Application
    Filed: July 7, 2008
    Publication date: August 5, 2010
    Inventors: Tetsuhiro Suzuki, Norikazu Ohshima, Shunsuke Fukami, Kiyokazu Nagahara, Nobuyuki Ishiwata