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).
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Publication number: 20130175645Abstract: A magnetoresistive effect element of the present invention includes: a domain wall motion layer, a spacer layer and a reference layer. The domain wall motion layer is made of ferromagnetic material with perpendicular magnetic anisotropy. The spacer layer is formed on the domain wall motion layer and made of non-magnetic material. The reference layer is formed on the spacer layer and made of ferromagnetic material, magnetization of the reference layer being fixed. The domain wall motion layer includes at least one domain wall, and stores data corresponding to a position of the domain wall. An anisotropy magnetic field of the domain wall motion layer is larger than a value in which the domain wall motion layer can hold the perpendicular magnetic anisotropy, and smaller than an essential value of an anisotropy magnetic field of the ferromagnetic material of the domain wall motion layer.Type: ApplicationFiled: December 14, 2010Publication date: July 11, 2013Applicant: NEC CORPORATIONInventors: Tadahiko Sugibayashi, Eiji Kariyada, Kaoru Mori, Norikazu Ohshima, Shunsuke Fukami, Tetsuhiro Suzuki, Hironobu Tanigawa, Sadahiko Miura, Nobuyuki Ishiwata
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Publication number: 20130140660Abstract: In a perpendicular magnetization domain wall motion MRAM in which the magnetizations of both ends of a magnetization free layer are pinned by magnetization pinned layers, the increase of a write current due to leakage magnetic field from the magnetization pinned layer is prevented. A first displacement is present between a first boundary line and a first vertical line, where a curve portion, which crosses a first magnetization free layer, of an outer circumferential line of a first magnetization pinned layer is the first boundary line, a segment which links a center of a magnetization free region and a center of a first magnetization pinned region is a first segment, and a segment, which is a vertical line of the first segment, and which comes in contact with the first boundary line is the first vertical line.Type: ApplicationFiled: June 16, 2011Publication date: June 6, 2013Inventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Nobuyuki Ishiwata, Norikazu Ohshima
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Patent number: 8416611Abstract: 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: GrantFiled: June 16, 2008Date of Patent: April 9, 2013Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata
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Patent number: 8379429Abstract: 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: GrantFiled: January 13, 2009Date of Patent: February 19, 2013Assignee: NEC CorporationInventors: Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara, Shunsuke Fukami
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Patent number: 8363461Abstract: 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: GrantFiled: June 26, 2009Date of Patent: January 29, 2013Assignee: NEC CorporationInventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8351249Abstract: A magnetic random access memory according to the present invention is provided with: a magnetic recording layer including a magnetization free region having a reversible magnetization, wherein a write current is flown through the magnetic recording layer in an in-plane direction; a magnetization fixed layer having a fixed magnetization; a non-magnetic layer provided between the magnetization free region and the magnetization fixed layer; and a heat sink structure provided to be opposed to the magnetic recording layer and having a function of receiving and radiating heat generated in the magnetic recording layer. The magnetic random access memory thus-structured radiates heat generated in the magnetic recording layer by using the heat sink structure, suppressing the temperature increase caused by the write current flown in the in-plane direction.Type: GrantFiled: April 9, 2007Date of Patent: January 8, 2013Assignee: NEC CorporationInventors: Nobuyuki Ishiwata, Hideaki Numata, Norikazu Ohshima
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Publication number: 20120326254Abstract: A magnetic random access memory according to the present invention is provided with: a magnetic recording layer including a magnetization free region having a reversible magnetization, wherein a write current is flown through the magnetic recording layer in an in-plane direction; a magnetization fixed layer having a fixed magnetization; a non-magnetic layer provided between the magnetization free region and the magnetization fixed layer; and a heat sink structure provided to be opposed to the magnetic recording layer and having a function of receiving and radiating heat generated in the magnetic recording layer. The magnetic random access memory thus-structured radiates heat generated in the magnetic recording layer by using the heat sink structure, suppressing the temperature increase caused by the write current flown in the in-plane direction.Type: ApplicationFiled: September 7, 2012Publication date: December 27, 2012Applicant: NEC CORPORATIONInventors: Nobuyuki ISHIWATA, Hideaki NUMATA, Norikazu OHSHIMA
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Publication number: 20120320667Abstract: A magnetic random access memory according to the present invention is provided with: a magnetic recording layer including a magnetization free region having a reversible magnetization, wherein a write current is flown through the magnetic recording layer in an in-plane direction; a magnetization fixed layer having a fixed magnetization; a non-magnetic layer provided between the magnetization free region and the magnetization fixed layer; and a heat sink structure provided to be opposed to the magnetic recording layer and having a function of receiving and radiating heat generated in the magnetic recording layer. The magnetic random access memory thus-structured radiates heat generated in the magnetic recording layer by using the heat sink structure, suppressing the temperature increase caused by the write current flown in the in-plane direction.Type: ApplicationFiled: August 21, 2012Publication date: December 20, 2012Applicant: NEC CORPORATIONInventors: Nobuyuki ISHIWATA, Hideaki NUMATA, Norikazu OHSHIMA
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Publication number: 20120278582Abstract: A magnetic memory element includes: a first magnetization free layer; a non-magnetic layer; a reference layer; a first magnetization fixed layer group; and a first blocking layer. The first magnetization free layer is composed of ferromagnetic material with perpendicular magnetic anisotropy and includes a first magnetization fixed region, a second magnetization fixed region and a magnetization free region. The non-magnetic layer is provided near the first magnetization free layer. The reference layer is composed of ferromagnetic material and provided on the non-magnetic layer. The first magnetization fixed layer group is provided near the first magnetization fixed region. The first blocking layer is provided being sandwiched between the first magnetization fixed layer group and the first magnetization fixed region or in the first magnetization fixed layer group.Type: ApplicationFiled: October 21, 2010Publication date: November 1, 2012Applicant: NEC CORPORATIONInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8194436Abstract: A magnetic random access memory includes: a first ferromagnetic layer; 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: GrantFiled: July 7, 2008Date of Patent: June 5, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8174873Abstract: 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: GrantFiled: December 10, 2008Date of Patent: May 8, 2012Assignee: NEC CorporationInventors: Tetsuhiro Suzuki, Shunsuke Fukami, Norikazu Ohshima, Kiyokazu Nagahara, Nobuyuki Ishiwata
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Patent number: 8174086Abstract: 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: GrantFiled: October 28, 2008Date of Patent: May 8, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima
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Patent number: 8159872Abstract: 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: GrantFiled: January 9, 2009Date of Patent: April 17, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Patent number: 8154913Abstract: A magnetoresistance effect element comprising: 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: GrantFiled: August 21, 2008Date of Patent: April 10, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Patent number: 8149615Abstract: 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: first and second magnetization fixed regions; and a magnetization free region. The magnetization free region and the second magnetization free layer are magnetically coupled to each other.Type: GrantFiled: January 9, 2009Date of Patent: April 3, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Patent number: 8120127Abstract: 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: GrantFiled: July 7, 2008Date of Patent: February 21, 2012Assignee: NEC CorporationInventors: Kiyokazu Nagahara, Shunsuke Fukami, Tetsuhiro Suzuki, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8120950Abstract: 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: GrantFiled: March 5, 2009Date of Patent: February 21, 2012Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima, Kiyokazu Nagahara
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Publication number: 20110298067Abstract: A magnetoresistive effect element includes: a magnetization free layer; a non-magnetic insertion layer provided adjacent to the magnetization free layer; a magnetic insertion layer provided adjacent to the non-magnetic insertion layer and opposite to the magnetization free layer with respect to the non-magnetic insertion layer; a spacer layer provided adjacent to the magnetic insertion layer and opposite to the non-magnetic insertion layer with respect to the magnetic insertion layer; and a first magnetization fixed layer provided adjacent to the spacer layer and opposite to the magnetic insertion layer with respect to the spacer layer. The magnetization free layer and the first magnetization fixed layer have magnetization components in directions approximately perpendicular to a film surface. The magnetization free layer includes two magnetization fixed portions and a domain wall motion portion arranged between the two magnetization fixed portions.Type: ApplicationFiled: February 15, 2010Publication date: December 8, 2011Applicant: NEC CORPORATIONInventors: Nobuyuki Ishiwata, Norikazu Ohshima, Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki
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Publication number: 20110297909Abstract: A magnetic memory element includes: a first magnetization free layer formed of a ferromagnetic material having perpendicular magnetic anisotropy; a second magnetization free layer provided near the first magnetization free layer and formed of a ferromagnetic material having in-plane magnetic anisotropy; a reference layer formed of a ferromagnetic material having in-plane magnetic anisotropy; and a non-magnetic layer provided between the second magnetization free layer and the reference layer. The first magnetization free layer includes: a first magnetization fixed region of which magnetization is fixed, a second magnetization fixed region of which magnetization is fixed, and a magnetization free region which is connected to the first magnetization fixed region and the second magnetization fixed region, and of which magnetization can be switched. The second magnetization free layer is included in the first magnetization free layer in a plane parallel to a substrate.Type: ApplicationFiled: January 28, 2010Publication date: December 8, 2011Inventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Nobuyuki Ishiwata, Norikazu Ohshima
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Publication number: 20110292718Abstract: A non-volatile logic circuit includes an input section, a control section and an output section. The input section has perpendicular magnetic anisotropy and has a ferromagnetic layer whose magnetization state is changeable. The control section includes a ferromagnetic layer. The output section is provided in a neighborhood of the input section and the control section and includes a magnetic tunnel junction element whose magnetization state is changeable. The magnetization state of the input section is changed based on the magnetization state. A magnetization state of the magnetic tunnel junction element of the output section which state is changed based on the magnetization state of the ferromagnetic material of the control section and the magnetization state of the ferromagnetic material of the input section.Type: ApplicationFiled: January 21, 2010Publication date: December 1, 2011Inventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Nobuyuki Ishiwata, Tadahiko Sugibayashi, Noburu Sakimura, Ryusuke Nebashi