Patents by Inventor Shoji Ikeda
Shoji Ikeda 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: 20170110654Abstract: Provided are a magneto resistive effect element with a stable magnetization direction perpendicular to a film plane and with a controlled magnetoresistance ratio, and a magnetic memory using the magneto resistive effect element. Ferromagnetic layers of the magneto resistive effect element are formed from a ferromagnetic material containing at least one type of 3d transition metal such that the magnetoresistance ratio is controlled, and the film thickness of the ferromagnetic layers is controlled on an atomic layer level such that the magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane.Type: ApplicationFiled: December 28, 2016Publication date: April 20, 2017Applicant: TOHOKU UNIVERSITYInventors: Hideo OHNO, Shoji IKEDA, Fumihiro MATSUKURA, Masaki ENDOH, Shun KANAI, Hiroyuki YAMAMOTO, Katsuya MIURA
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Patent number: 9577182Abstract: A magnetoresistance effect element and a magnetic memory having thermal stability expressed by a thermal stability factor of 70 or more even with a fine junction size. The magnetoresistance effect element includes a first magnetic layer of an invariable magnetization direction forming a reference layer, a second magnetic layer of a variable magnetization direction forming a recording layer, and a first non-magnetic layer disposed between the first and second magnetic layers in a thickness direction of the first and second magnetic layers. At least one of the first and second magnetic layers has the following relationship between D (nm) and t (nm): D<0.9t+13, where D is a junction size corresponding to the length of a longest straight line on an end surface perpendicular to the thickness direction, and t is a layer thickness. The junction size is 30 nm or less.Type: GrantFiled: October 20, 2014Date of Patent: February 21, 2017Assignee: TOHOKU UNIVERSITYInventors: Shoji Ikeda, Hideo Sato, Shunsuke Fukami, Michihiko Yamanouchi, Fumihiro Matsukura, Hideo Ohno, Shinya Ishikawa
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Patent number: 9564152Abstract: Provided are a magneto resistive effect element with a stable magnetization direction perpendicular to a film plane and with a controlled magnetoresistance ratio, and a magnetic memory using the magneto resistive effect element. Ferromagnetic layers 106 and 107 of the magneto resistive effect element are formed from a ferromagnetic material containing at least one type of 3d transition metal such that the magnetoresistance ratio is controlled, and the film thickness of the ferromagnetic layers is controlled on an atomic layer level such that the magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane.Type: GrantFiled: March 25, 2014Date of Patent: February 7, 2017Assignee: TOHOKU UNIVERSITYInventors: Hideo Ohno, Shoji Ikeda, Fumihiro Matsukura, Masaki Endoh, Shun Kanai, Hiroyuki Yamamoto, Katsuya Miura
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Publication number: 20170025600Abstract: A magnetoresistive element includes a reference layer having a fixed magnetization direction and including a ferromagnetic material containing Fe or Co, a recording layer having a variable magnetization direction and including a ferromagnetic material, and one non-magnetic layer that is formed between the reference layer and the recording layer and that contains oxygen. One of the reference layer and the recording layer contains Fe. The three layers are arranged so that a magnetization direction of the one of the reference layer and the recording layer becomes perpendicular to a layer surface by an interfacial perpendicular magnetic anisotropy at an interface between the one of the reference layer and the recording layer and the one non-magnetic layer resulting from the one of the reference layer and the recording layer having a predetermined thickness. The one of the reference layer and the recording layer has a bcc structure.Type: ApplicationFiled: August 30, 2016Publication date: January 26, 2017Applicant: TOHOKU UNIVERSITYInventors: Hideo OHNO, Shoji IKEDA, Fumihiro MATSUKURA, Masaki ENDOH, Shun KANAI, Katsuya MIURA, Hiroyuki YAMAMOTO
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Publication number: 20160329086Abstract: A control method for a magnetoresistance effect element and a control device for the magnetoresistance effect element that provide a higher writing speed and lower power consumption. When the magnetization direction of a second magnetic layer is nearly parallel to the magnetization direction of a first magnetic layer, a first voltage is applied across the first and second magnetic layer so that the magnetization direction of the second magnetic layer is reversed by modifying the direction of the magnetization easy axis thereof, followed by the application of a second voltage. When the magnetization direction of the second magnetic layer is nearly antiparallel to the magnetization direction of the first magnetic layer, a third voltage is applied across the first magnetic layer and the second magnetic layer, followed by the application of a fourth voltage so that current flows from the second magnetic layer toward the first magnetic layer.Type: ApplicationFiled: November 13, 2014Publication date: November 10, 2016Applicant: Tohoku UniversityInventors: Shun KANAI, Fumihiro MATSUKURA, Hideo OHNO, Michihiko YAMANOUCHI, Shoji IKEDA, Hideo SATO
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Patent number: 9450177Abstract: There is provided a magnetoresistive element whose magnetization direction is stable in a direction perpendicular to the film surface and whose magnetoresistance ratio is controlled, as well as magnetic memory using such a magnetoresistive element. By having the material of a ferromagnetic layer forming the magnetoresistive element comprise a ferromagnetic material containing at least one type of 3d transition metal, or a Heusler alloy, to control the magnetoresistance ratio, and by controlling the thickness of the ferromagnetic layer on an atomic layer level, the magnetization direction is changed from being in-plane with the film surface to being perpendicular to the film surface.Type: GrantFiled: February 14, 2011Date of Patent: September 20, 2016Assignee: TOHOKU UNIVERSITYInventors: Hideo Ohno, Shoji Ikeda, Fumihiro Matsukura, Masaki Endoh, Shun Kanai, Katsuya Miura, Hiroyuki Yamamoto
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Publication number: 20160233416Abstract: A magnetoresistance effect element and a magnetic memory having thermal stability expressed by a thermal stability factor of 70 or more even with a fine junction size. The magnetoresistance effect element includes a first magnetic layer of an invariable magnetization direction forming a reference layer, a second magnetic layer of a variable magnetization direction forming a recording layer, and a first non-magnetic layer disposed between the first and second magnetic layers in a thickness direction of the first and second magnetic layers. At least one of the first and second magnetic layers has the following relationship between D (nm) and t (nm): D<0.9t+13, where D is a junction size corresponding to the length of a longest straight line on an end surface perpendicular to the thickness direction, and t is a layer thickness. The junction size is 30 nm or less.Type: ApplicationFiled: October 20, 2014Publication date: August 11, 2016Applicant: TOHOKU UNIVERSITYInventors: Shoji IKEDA, Hideo SATO, Shunsuke FUKAMI, Michihiko YAMANOUCHI, Fumihiro MATSUKURA, Hideo OHNO, Shinya ISHIKAWA
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Patent number: 9202545Abstract: A magnetoresistance effect element including a recording layer of high thermal stability to perform perpendicular magnetic recording within a film surface, and a magnetic memory using the element. The element includes: a first ferromagnetic layer of an invariable magnetization direction; a second ferromagnetic layer of a variable magnetization direction; a first non-magnetic layer between the first and second ferromagnetic layers; current supply terminals connected to the first and second ferromagnetic layers; a non-magnetic coupling layer on a surface of the second ferromagnetic layer opposite the first non-magnetic layer; a third ferromagnetic layer of a variable magnetization direction on a surface of the non-magnetic coupling layer opposite the second ferromagnetic layer; and a second non-magnetic layer on a surface of the third ferromagnetic layer opposite the non-magnetic coupling layer.Type: GrantFiled: March 25, 2013Date of Patent: December 1, 2015Assignee: TOHOKU UNIVERSITYInventors: Hideo Sato, Shunsuke Fukami, Michihiko Yamanouchi, Shoji Ikeda, Fumihiro Matsukura, Hideo Ohno
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Publication number: 20150332818Abstract: A magnetic material includes a structure in which a first magnetic layer 1 and a second magnetic layer 2 are stacked such that each layer is formed at least partially in a stacking direction by substantially one atomic layer. The first magnetic layer contains Co as a principal component. The second magnetic layer includes at least Ni. The magnetic material has magnetic anisotropy in the stacking direction. Preferably, an atomic arrangement within a film surface of the first magnetic layer and the second magnetic layer has six-fold symmetry.Type: ApplicationFiled: November 11, 2013Publication date: November 19, 2015Inventors: Shunsuke FUKAMI, Hideo SATO, Michihiko YAMANOUCHI, Shoji IKEDA, Hideo OHNO
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Patent number: 9153306Abstract: Provided is a tunnel magnetoresistive effect element such that a high TMR ratio and a low write current can be realized, and the thermal stability factor (E/kBT) of a recording layer and a pinned layer is increased while an increase in resistance of the element as a whole is suppressed, thus enabling a stable operation. On at least one of a recording layer 21 and a pinned layer 22 each comprising CoFeB, electrically conductive oxide layers 31 and 32 are disposed on a side opposite to a tunnel barrier layer 10.Type: GrantFiled: November 8, 2011Date of Patent: October 6, 2015Assignee: TOHOKU UNIVERSITYInventors: Hideo Ohno, Shoji Ikeda, Hiroyuki Yamamoto, Yosuke Kurosaki, Katsuya Miura
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Patent number: 9135973Abstract: Provided are a magnetoresistance effect element with a stable magnetization direction perpendicular to film plane and a controlled magnetoresistance ratio, in which writing can be performed by magnetic domain wall motion, and a magnetic memory including the magnetoresistance effect element. The magnetoresistance ratio is controlled by forming a ferromagnetic layer of the magnetoresistance effect element from a ferromagnetic material including at least one type of 3d transition metal or a Heusler alloy. The magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane by controlling the film thickness of the ferromagnetic layer on an atomic layer level.Type: GrantFiled: May 26, 2011Date of Patent: September 15, 2015Assignee: TOHOKU UNIVERSITYInventors: Hideo Ohno, Shoji Ikeda, Fumihiro Matsukura, Masaki Endoh, Shun Kanai, Katsuya Miura, Hiroyuki Yamamoto
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Patent number: 9070457Abstract: In magnetic tunnel junctions manufactured with use of a ferromagnetic material having perpendicular magnetic anisotropy, a difference in record retention time depending on stored information due to an imbalance in thermal stability between a parallel state and an anti-parallel state of magnetization, which correspond to bit information, is alleviated. A reference layer and a recording layer which constitute a magnetic tunnel junction are made different in area from each other so as to correct the difference in record retention time corresponding to stored information.Type: GrantFiled: May 24, 2012Date of Patent: June 30, 2015Assignee: Tohoku UniversityInventors: Hideo Ohno, Shoji Ikeda, Michihiko Yamanouchi, Hideo Sato, Katsuya Miura
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Patent number: 9042165Abstract: A magnetoresistive effect element uses a perpendicularly magnetized material and has a high TMR ratio. Intermediate layers composed of an element metal having a melting point of 1600° C. or an alloy containing the metal on an outside of a structure consisting of a CoFeB layer, an MgO barrier layer, and a CoFeB layer. By inserting the intermediate layers, crystallization of the CoFeB layer during annealing is advanced from an MgO (001) crystal side, so that the CoFeB layer has a crystalline orientation in bcc (001).Type: GrantFiled: January 25, 2011Date of Patent: May 26, 2015Assignees: Hitachi, Ltd., Tohoku UniversityInventors: Shoji Ikeda, Hideo Ohno, Hiroyuki Yamamoto, Kenchi Ito, Hiromasa Takahashi
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Publication number: 20150109853Abstract: A magnetoresistance effect element including a recording layer of high thermal stability to perform perpendicular magnetic recording within a film surface, and a magnetic memory using the element. The element includes: a first ferromagnetic layer of an invariable magnetization direction; a second ferromagnetic layer of a variable magnetization direction; a first non-magnetic layer between the first and second ferromagnetic layers; current supply terminals connected to the first and second ferromagnetic layers; a non-magnetic coupling layer on a surface of the second ferromagnetic layer opposite the first non-magnetic layer; a third ferromagnetic layer of a variable magnetization direction on a surface of the non-magnetic coupling layer opposite the second ferromagnetic layer; and a second non-magnetic layer on a surface of the third ferromagnetic layer opposite the non-magnetic coupling layer.Type: ApplicationFiled: March 25, 2013Publication date: April 23, 2015Applicant: TOHOKU UNIVERSITYInventors: Hideo Sato, Shunsuke Fukami, Michihiko Yamanouchi, Shoji Ikeda, Fumihiro Matsukura, Hideo Ohno
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Patent number: 8993351Abstract: [Object] To provide a method of manufacturing a perpendicular magnetization-type magnetic element, which does not need a step of depositing MgO. [Solving Means] The method of manufacturing a magnetoresistive element 1 according to the present invention includes laminating a first layer 30 on a base 10, the first layer 30 including a material containing at least one of Co, Ni, and Fe. Next, a second layer 40 is laminated on the first layer 30, the second layer 40 including Mg. Next, the Mg in the second layer 40 is oxidized to form MgO by applying an oxidation treatment to a laminated body including the first layer 30 and the second layer 40. Next, the second layer 40 is crystallized by applying a heat treatment to the laminated body, and the first layer 30 is caused to be perpendicularly magnetized. According to the manufacturing method, it is possible to manufacture a perpendicular magnetization-type CoFeB—MgO magnetic element without causing a problem arising from the deposition of MgO.Type: GrantFiled: December 20, 2011Date of Patent: March 31, 2015Assignees: Tohoku University, Ulvac, Inc.Inventors: Hiroki Yamamoto, Tadashi Morita, Hideo Ohno, Shoji Ikeda
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Patent number: 8917541Abstract: Provided are a magneto resistive effect element with a stable magnetization direction perpendicular to a film plane and with a controlled magnetoresistance ratio, and a magnetic memory using the magneto resistive effect element. Ferromagnetic layers 106 and 107 of the magneto resistive effect element are formed from a ferromagnetic material containing at least one type of 3d transition metal such that the magnetoresistance ratio is controlled, and the film thickness of the ferromagnetic layers is controlled on an atomic layer level such that the magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane.Type: GrantFiled: May 31, 2011Date of Patent: December 23, 2014Assignees: Hitachi, Ltd., Tohoku UniversityInventors: Hideo Ohno, Shoji Ikeda, Fumihiro Matsukura, Masaki Endoh, Shun Kanai, Hiroyuki Yamamoto, Katsuya Miura
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Publication number: 20140340961Abstract: Provided is a tunnel magnetoresistive effect element such that a high TMR ratio and a low write current can be realized, and the thermal stability factor (E/kBT) of a recording layer and a pinned layer is increased while an increase in resistance of the element as a whole is suppressed, thus enabling a stable operation. On at least one of a recording layer 21 and a pinned layer 22 each comprising CoFeB, electrically conductive oxide layers 31 and 32 are disposed on a side opposite to a tunnel barrier layer 10.Type: ApplicationFiled: November 8, 2011Publication date: November 20, 2014Applicants: HITACHI, LTD., TOHOKU UNIVERSITYInventors: Hideo Ohno, Shoji Ikeda, Hiroyuki Yamamoto, Yosuke Kurosaki, Katsuya Miura
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Patent number: 8837209Abstract: A relation between a drive current of a selection transistor of a magnetic memory and a threshold magnetization switching current of the magnetoresistance effect element is optimized. In order to optimize the relation between the drive current of the selection transistor and the threshold magnetization switching current of the magnetoresistance effect element 101 of the magnetic memory cell, a mechanism 601-604 for dropping the threshold magnetization switching current on “1” writing is provided that applies a magnetic field that is in the inverse direction of the pinned layer to the recording layer of the magnetoresistance effect element.Type: GrantFiled: February 17, 2011Date of Patent: September 16, 2014Assignees: Hitachi, Ltd., Tohoku UniversityInventors: Hideo Ohno, Shoji Ikeda, Katsuya Miura, Kazuo Ono, Riichiro Takemura, Hiromasa Takahashi
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Publication number: 20140205862Abstract: Provided are a magneto resistive effect element with a stable magnetization direction perpendicular to a film plane and with a controlled magnetoresistance ratio, and a magnetic memory using the magneto resistive effect element. Ferromagnetic layers 106 and 107 of the magneto resistive effect element are formed from a ferromagnetic material containing at least one type of 3d transition metal such that the magnetoresistance ratio is controlled, and the film thickness of the ferromagnetic layers is controlled on an atomic layer level such that the magnetization direction is changed from a direction in the film plane to a direction perpendicular to the film plane.Type: ApplicationFiled: March 25, 2014Publication date: July 24, 2014Applicant: Tohoku UniversityInventors: Hideo Ohno, Shoji Ikeda, Fumihiro Matsukura, Masaki Endoh, Shun Kanai, Hiroyuki Yamamoto, Katsuya Miura
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Publication number: 20140097509Abstract: A disclosed magnetic memory element includes: a magnetization free layer formed of a ferromagnetic substance having perpendicular magnetic anisotropy; a response layer provided so as to be opposed to the magnetization free layer and formed of a ferromagnetic substance having perpendicular magnetic anisotropy; a non-magnetic layer provided so as to be opposed to the response layer on a side opposite to the magnetization free layer and formed of a non-magnetic substance; and a reference layer provided so as to be opposed to the non-magnetic layer on a side opposite to the response layer and formed of a ferromagnetic substance having perpendicular magnetic anisotropy. The magnetization free layer includes a first magnetization fixed region and a second magnetization fixed region which have magnetization fixed in directions antiparallel to each other, and a magnetization free region in which a magnetization direction is variable.Type: ApplicationFiled: April 19, 2012Publication date: April 10, 2014Applicant: TOHOKU UNIVERSITYInventors: Shunsuke Fukami, Nobuyuki Ishiwata, Tadahiko Sugibayashi, Hideo Ohno, Shoji Ikeda, Michihiko Yamanouchi