Patents by Inventor Kiyokazu Nagahara
Kiyokazu Nagahara 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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Patent number: 8994130Abstract: 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: GrantFiled: January 28, 2010Date of Patent: March 31, 2015Assignee: NEC CorporationInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Nobuyuki Ishiwata, Norikazu Ohshima
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Publication number: 20140346518Abstract: A magnetic memory includes a magnetic memory, including a ferromagnetic underlayer including a magnetic material, a non-magnetic intermediate layer disposed on the underlayer, a ferromagnetic data recording layer formed on the intermediate layer and having a perpendicular magnetic anisotropy, a reference layer connected to the data recording layer across a non-magnetic layer, and first and second magnetization fixed layers disposed in contact with a bottom face of the underlayer. The data recording layer includes a magnetization free region having a reversible magnetization and opposed to the reference layer, a first magnetization fixed region coupled to a first border of the magnetization free layer and having a magnetization fixed in a first direction, and a second magnetization fixed region coupled to a second border of the magnetization free layer and having a magnetization fixed in a second direction opposite to the first direction.Type: ApplicationFiled: August 8, 2014Publication date: November 27, 2014Inventors: Eiji Kariyada, Katsumi Suemitsu, Hironobu Tanigawa, Kaoru Mori, Tetsuhiro Suzuki, Kiyokazu Nagahara, Yasuaki Ozaki, Norikazu Ohshima
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Patent number: 8884388Abstract: A magnetic memory element includes: a first magnetization free layer configured to be composed of ferromagnetic material with perpendicular magnetic anisotropy; a reference layer configured to be provided near the first magnetization free layer; a non-magnetic layer configured to be provided adjacent to the reference layer; and a step formation layer configured to be provided under the first magnetization free 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 configured to be connected with the first magnetization fixed region and the second magnetization fixed region. The first magnetization free layer has at least one of a step, a groove and a protrusion inside.Type: GrantFiled: March 9, 2011Date of Patent: November 11, 2014Assignee: NEC CorporationInventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki
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Patent number: 8830735Abstract: A magnetic memory includes: a magnetization fixed layer having perpendicular magnetic anisotropy, a magnetization direction of the magnetization fixed layer being fixed; an interlayer dielectric; an underlayer formed on upper faces of the magnetization fixed layer and the interlayer dielectric; and a data recording layer formed on an upper face of the underlayer and having perpendicular magnetic anisotropy. The underlayer includes: a first magnetic underlayer; and a non-magnetic underlayer formed on the first magnetic underlayer. The first magnetic underlayer is formed with such a thickness that the first magnetic underlayer does not exhibit in-plane magnetic anisotropy in a portion of the first magnetic underlayer formed on the interlayer dielectric.Type: GrantFiled: November 23, 2011Date of Patent: September 9, 2014Assignee: Renesas Electronics CorporationInventors: Eiji Kariyada, Katsumi Suemitsu, Hironobu Tanigawa, Kaoru Mori, Tetsuhiro Suzuki, Kiyokazu Nagahara, Yasuaki Ozaki, Norikazu Ohshima
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Patent number: 8791534Abstract: 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: GrantFiled: June 16, 2011Date of Patent: July 29, 2014Assignee: NEC CorporationInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Nobuyuki Ishiwata, Norikazu Ohshima
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Patent number: 8787076Abstract: 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: GrantFiled: August 13, 2009Date of Patent: July 22, 2014Assignee: NEC CorporationInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima
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Patent number: 8687414Abstract: 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: GrantFiled: December 24, 2009Date of Patent: April 1, 2014Assignee: NEC CorporationInventors: Kiyokazu Nagahara, Shunsuke Fukami, Nobuyuki Ishiwata, Tetsuhiro Suzuki, Norikazu Ohshima
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Patent number: 8625327Abstract: 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: GrantFiled: July 2, 2009Date of Patent: January 7, 2014Assignee: NEC CorporationInventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Oshima, Nobuyuki Ishiwata
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Patent number: 8592930Abstract: 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: GrantFiled: October 21, 2010Date of Patent: November 26, 2013Assignee: NEC CorporationInventors: Shunsuke Fukami, Tetsuhiro Suzuki, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8565011Abstract: 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: GrantFiled: October 29, 2009Date of Patent: October 22, 2013Assignee: NEC CorporationInventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki, Nobuyuki Ishiwata, Norikazu Ohshima
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Patent number: 8559214Abstract: 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: GrantFiled: December 24, 2009Date of Patent: October 15, 2013Assignee: NEC CorporationInventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki, Nobuyuki Ishiwata, Norikazu Ohshima
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Patent number: 8537604Abstract: 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: GrantFiled: October 16, 2009Date of Patent: September 17, 2013Assignee: NEC CorporationInventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Norikazu Ohshima, Nobuyuki Ishiwata
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Patent number: 8514616Abstract: 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: GrantFiled: February 15, 2010Date of Patent: August 20, 2013Assignee: NEC CorporationInventors: Nobuyuki Ishiwata, Norikazu Ohshima, Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki
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Patent number: 8503222Abstract: 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: GrantFiled: January 21, 2010Date of Patent: August 6, 2013Assignee: NEC CorporationInventors: Tetsuhiro Suzuki, Shunsuke Fukami, Kiyokazu Nagahara, Nobuyuki Ishiwata, Tadahiko Sugibayashi, Noboru Sakimura, Ryusuke Nebashi
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Patent number: 8481339Abstract: A magnetic memory has a magnetic recording layer, a reference layer connected via a non-magnetic layer to the magnetic recording layer, first and second magnetization pinning layers disposed below the magnetic recording layer. The magnetic recording layer and the reference layer have a perpendicular magnetic anisotropy. The magnetic recording layer has a magnetization reversal region having a reversible magnetization and overlapping the difference layer, a first magnetization pinned region connected to a first boundary of the magnetization reversal region with the direction of the magnetization being fixed in a first direction, and a second magnetization pinned region connected to a second boundary of the magnetization reversal region with the direction of magnetization being fixed in a second direction anti-parallel to the first direction. The first and the second magnetization pinning layers fix the magnetization of the first and the second magnetization pinned regions.Type: GrantFiled: January 27, 2012Date of Patent: July 9, 2013Assignee: Renesas Electronics CorporationInventors: Kiyokazu Nagahara, Eiji Kariyada
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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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Publication number: 20130113058Abstract: A magnetic memory element includes: a first magnetization free layer configured to be composed of ferromagnetic material with perpendicular magnetic anisotropy; a reference layer configured to be provided near the first magnetization free layer; a non-magnetic layer configured to be provided adjacent to the reference layer; and a step formation layer configured to be provided under the first magnetization free 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 configured to be connected with the first magnetization fixed region and the second magnetization fixed region. The first magnetization free layer has at least one of a step, a groove and a protrusion inside.Type: ApplicationFiled: March 9, 2011Publication date: May 9, 2013Applicant: NEC CORPORATIONInventors: Shunsuke Fukami, Kiyokazu Nagahara, Tetsuhiro Suzuki
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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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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