Patents by Inventor Tohru Oikawa
Tohru Oikawa 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: 20120267734Abstract: A spin transport device includes a semiconductor layer 3, a first ferromagnetic layer 1 provided on the semiconductor layer 3 via a first tunnel barrier layer 5A, and a second ferromagnetic layer 2 provided on the semiconductor layer 3 via a second tunnel barrier layer 5B to be spaced from the first ferromagnetic layer 1, and the semiconductor layer 3 includes a first region RI broadening in a direction away from the first ferromagnetic layer 1 along a direction orthogonal to a thickness direction from the first ferromagnetic layer 1, and a second region R12 extending in a direction toward the second ferromagnetic layer 2 along the direction orthogonal to the thickness direction from the first ferromagnetic layer 1. The second region R12 has a relatively higher impurity concentration than the first region R1.Type: ApplicationFiled: April 12, 2012Publication date: October 25, 2012Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA
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Publication number: 20120241883Abstract: The present invention provides a spin transport device having lowered areal resistance in its tunneling layer and a magnetic head. The spin transport device (magnetic sensor 1) comprises a channel layer 10 constituted by a semiconductor, ferromagnetic layers 20A, 20B formed on the channel layer 10, and tunneling layers 22A, 22B formed so as to be interposed between the channel layer 10 and ferromagnetic layers 20A, 20B, while the tunneling layers 22A, 22B are constituted by a material substituting a part of Mg in MgO with Zn. As a result of studies, the inventors observed a decrease in areal resistance in a tunnel material having substituted a part of Mg in MgO with Zn. Therefore, the tunneling layers 22A, 22B can lower their areal resistance when constructed by a material having substituted a part of Mg in MgO with Zn.Type: ApplicationFiled: March 1, 2012Publication date: September 27, 2012Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Yoshihiro TSUCHIYA
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Patent number: 8269294Abstract: A spin transport device is provided, which includes a channel comprised of a semiconductor material, a magnetization fixed layer arranged on the channel via a first insulating layer, a magnetization free layer arranged on the channel via a second insulating layer, and first and second electrodes arranged on the channel, wherein carrier densities of a first region of the channel including a contact surface with the first insulating layer, a second region of the channel including a contact surface with the second insulating layer, a third region of the channel including an opposite surface to the first electrode, and a fourth region of the channel including an opposite surface to the second electrode are higher than an average carrier density of the whole channel. Accordingly, a spin transport device that can realize good spin transportation and electric resistance characteristics while suppressing the scattering of spin can be provided.Type: GrantFiled: June 8, 2010Date of Patent: September 18, 2012Assignee: TDK CorporationInventors: Tomoyuki Sasaki, Tohru Oikawa, Katsumichi Tagami, Masaki Kubota
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Publication number: 20120228683Abstract: This spin device includes a semiconductor layer 3 formed of single crystalline Si, a first tunnel insulating layer T1 formed on a surface of the semiconductor layer 3, and a first ferromagnetic metal layer 1 formed on the first tunnel insulating layer T1. Area density of dangling bonds in an interface between the semiconductor layer 3 and the first tunnel insulating layer T1 is 3×1014/cm2 or less. In this case, a polarization rate can be greatly improved.Type: ApplicationFiled: March 9, 2012Publication date: September 13, 2012Applicant: TDK CORPORATIONInventors: Tohru OIKAWA, Tomoyuki SASAKI, Yoshitomo TANAKA, Kiyoshi NOGUCHI
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Publication number: 20120211848Abstract: The magnetic sensor includes a base substrate having a magnetic shield layer; a single-domain semiconductor crystal layer attached via an insulating film on the magnetic shield layer of the base substrate; a first ferromagnetic layer formed on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a first tunnel barrier layer; and a second ferromagnetic layer formed, at a distance from the first ferromagnetic layer, on top of the semiconductor crystal layer on the opposite side of the semiconductor crystal layer to the insulating film, via a second tunnel barrier layer.Type: ApplicationFiled: February 14, 2012Publication date: August 23, 2012Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Kiyoshi NOGUCHI
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Publication number: 20120074510Abstract: A magnetic sensor 1 comprises a main channel layer 7a having first, second, and third regions 71, 72, 73 and extending in a first direction; a first ferromagnetic layer 12A mounted on the first region 71; a second ferromagnetic layer 12B mounted on the second region 72; a projection channel layer 7b projecting in a direction perpendicular to a thickness direction of the main channel layer 7a from a side face of the third region 73 between the first and second regions 71, 72 in the main channel layer 7a; and a magnetic shield S covering both sides in the thickness direction of the projection channel layer 7b and both sides in the first direction of the projection channel layer 7b and exposing an end face 7c in the projecting direction of the projection channel layer 7b.Type: ApplicationFiled: September 7, 2011Publication date: March 29, 2012Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA
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Publication number: 20120056254Abstract: The present invention provides a spin injection electrode structure, a spin transport element, and a spin transport device which enable effective spin injection in a silicon channel layer at room temperature. A spin injection electrode structure IE comprises a silicon channel layer 12, a first magnesium oxide film 13A disposed on a first part of the silicon channel layer 12, and a first ferromagnetic layer 14A disposed on the first magnesium oxide film 13A. The first magnesium oxide film 13A partly includes a first lattice-matched part P lattice-matched with both of the silicon channel layer 12 and the first ferromagnetic layer 14A.Type: ApplicationFiled: August 24, 2011Publication date: March 8, 2012Applicants: AKITA PREFECTURE, TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Kiyoshi NOGUCHI, Toshio SUZUKI
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Publication number: 20120038355Abstract: A magnetic sensor is provided with a channel of a semiconductor, a first insulating film and a metal body arranged opposite to each other with the channel in between, a ferromagnet provided on the first insulating film, a first reference electrode connected to the metal body, a second reference electrode connected to the metal body, a magnetic shield covering a portion opposed to the ferromagnet in the channel, and a second insulating film provided between the channel and the magnetic shield. The magnetic shield has a through hole extending toward the portion opposed to the ferromagnet in the channel.Type: ApplicationFiled: July 1, 2011Publication date: February 16, 2012Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA
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Publication number: 20110204886Abstract: A magnetic sensor comprises a first ferromagnetic body, a second ferromagnetic body, a channel extending from the first ferromagnetic body to the second ferromagnetic body, a magnetic shield covering the channel, and an insulating film disposed between the channel and the magnetic shield, while the magnetic shield has a through-hole extending toward the channel.Type: ApplicationFiled: January 31, 2011Publication date: August 25, 2011Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Kiyoshi NOGUCHI
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Publication number: 20110205666Abstract: A magnetic sensor comprises a channel, a ferromagnetic body and first and second reference electrodes on the channel, a magnetic shield covering a part of the channel opposing the ferromagnetic body, and an insulating film disposed between the channel and the magnetic shield, while the magnetic shield has a through-hole extending toward the part of the channel opposing the ferromagnetic body.Type: ApplicationFiled: January 31, 2011Publication date: August 25, 2011Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Kiyoshi NOGUCHI
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Publication number: 20100327333Abstract: A spin transport device which comprises a channel, first and second insulating layers, a magnetization fixed layer, a magnetization free layer, first and second wirings, and satisfies at least one of following conditions A and B, Condition A: The first wiring includes a vertical portion which extends in a thickness direction of the magnetization fixed layer on the magnetization fixed layer, and a horizontal portion which extends from the vertical portion that is apart from the magnetization fixed layer side in a direction crossing the thickness direction of the magnetization fixed layer, and Condition B: The second wiring includes a vertical portion which extends in a thickness direction of the magnetization free layer on the magnetization free layer, and a horizontal portion which extends from the vertical portion that is apart from the magnetization free layer side in a direction crossing the thickness direction of the magnetization free layer.Type: ApplicationFiled: June 23, 2010Publication date: December 30, 2010Applicant: TDK CORPORATIONInventors: Tomoyuki Sasaki, Tohru Oikawa, Katsumichi Tagami
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Publication number: 20100314702Abstract: A spin transport device is provided, which includes a channel comprised of a semiconductor material, a magnetization fixed layer arranged on the channel via a first insulating layer, a magnetization free layer arranged on the channel via a second insulating layer, and first and second electrodes arranged on the channel, wherein carrier densities of a first region of the channel including a contact surface with the first insulating layer, a second region of the channel including a contact surface with the second insulating layer, a third region of the channel including an opposite surface to the first electrode, and a fourth region of the channel including an opposite surface to the second electrode are higher than an average carrier density of the whole channel. Accordingly, a spin transport device that can realize good spin transportation and electric resistance characteristics while suppressing the scattering of spin can be provided.Type: ApplicationFiled: June 8, 2010Publication date: December 16, 2010Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru Oikawa, Katsumichi Tagami, Masaki Kubota
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Patent number: 7826254Abstract: In the magnetic storage device, magnetization characteristics during write cycles are homogenized, and write cycles are carried out efficiently. In the magnetic storage device, the soft magnetic body is formed so as to cover the line either totally or partially, and the anti-ferromagnetic layer is formed on the outer surface of this soft magnetic body. Furthermore, the magneto-resistive element is disposed in the vicinity of the line. Suppose the case where the exchange coupling energy at the interface between the soft magnetic body and the anti-ferromagnetic layer is J (erg/cm2), the saturation magnetization of the soft magnetic body is Ms (emu/cc), and the coercive force of the soft magnetic body is Hc (Oe). Then, the thickness t (cm) of the soft magnetic body is selected to be such that t<J/(Hc·Ms).Type: GrantFiled: June 6, 2007Date of Patent: November 2, 2010Assignee: TDK CorporationInventors: Susumu Haratani, Tohru Oikawa, Takashi Asatani
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Publication number: 20100213519Abstract: An object of the present invention is to provide a silicon spin transport device manufacturing method and silicon spin transport device whereby improved voltage output characteristics can be obtained. The silicon spin transport device manufacturing method comprises: a first step of patterning a silicon film by wet etching and forming a silicon channel layer; and a second step of forming a magnetization free layer and a magnetization fixed layer, which are apart from each other, on the silicon channel layer.Type: ApplicationFiled: January 20, 2010Publication date: August 26, 2010Applicant: TDK CORPORATIONInventors: Tomoyuki SASAKI, Tohru OIKAWA, Katsumichi TAGAMI
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Patent number: 7697323Abstract: A magnetic storage device is provided which has significantly reduced power consumption. The magnetic storage device includes: a yoke which is arranged so as to cover part of a line extending in an arbitrary direction; and a magneto-resistive element which is arranged near the line and is capable of writing information using a field occurring from the line. The magnetic storage device is set to satisfy the equation Iw?a·R+b, where Iw is the write current necessary for the line, R is the magnetoresistance of the yoke, a (mA·H)=7.5E?11, and b (mA)=0.1.Type: GrantFiled: June 25, 2007Date of Patent: April 13, 2010Assignee: TDK CorporationInventors: Katsumichi Tagami, Keiji Koga, Tohru Oikawa
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Patent number: 7649766Abstract: A magnetic storage device with a significant reduction in power consumption. The magnetic storage device includes: a yoke which is arranged to cover part of a line extending in an arbitrary direction; and a magneto-resistive element which is arranged in contact with the yoke, thereby forming a closed magnetic circuit. The magneto-resistive element is capable of writing information with a field emanating from the yoke. The magnetic storage device satisfies Iw?a·R, where R is the magnetoresistance of the yoke, Iw is the write current necessary for the line, and a (mA·H)=6E?11.Type: GrantFiled: December 14, 2007Date of Patent: January 19, 2010Assignee: TDK CorporationInventors: Keiji Koga, Katsumichi Tagami, Tohru Oikawa
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Patent number: 7471551Abstract: The direction of magnetization of a reading ferromagnetic material 5R forming a spin filter when reading is the same as that of a pinned layer 1. In this case, a torque that works on the spin of a free layer 3 due to a spin polarized current becomes “zero.” When the element size is made small so as to improve the integration degree of the magnetic memory, according to the scaling law, the writing current can be made small. In the present invention, the resistance to the spin injection magnetization reversal due to a reading current is high, so that the magnitude of the writing current can be lowered.Type: GrantFiled: May 23, 2007Date of Patent: December 30, 2008Assignee: TDK CorporationInventor: Tohru Oikawa
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Publication number: 20080144227Abstract: A magnetic storage device with a significant reduction in power consumption. The magnetic storage device includes: a yoke which is arranged to cover part of a line extending in an arbitrary direction; and a magneto-resistive element which is arranged in contact with the yoke, thereby forming a closed magnetic circuit. The magneto-resistive element is capable of writing information with a field emanating from the yoke. The magnetic storage device satisfies Iw?a·R, where R is the magnetoresistance of the yoke, Iw is the write current necessary for the line, and a (mA·H)=6E?11.Type: ApplicationFiled: December 14, 2007Publication date: June 19, 2008Inventors: Keiji Koga, Katsumichi Tagami, Tohru Oikawa
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Publication number: 20080024935Abstract: A magnetic storage device is provided which has significantly reduced power consumption. The magnetic storage device includes: a yoke which is arranged so as to cover part of a line extending in an arbitrary direction; and a magneto-resistive element which is arranged near the line and is capable of writing information using a field occurring from the line. The magnetic storage device is set to satisfy the equation Iw?a·R+b, where Iw is the write current necessary for the line, R is the magnetoresistance of the yoke, a (mA·H)=7.5E?11, and b (mA)=0.1.Type: ApplicationFiled: June 25, 2007Publication date: January 31, 2008Inventors: Katsumichi Tagami, Keiji Koga, Tohru Oikawa
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Publication number: 20080006890Abstract: In the magnetic storage device, magnetization characteristics during write cycles are homogenized, and write cycles are carried out efficiently. In the magnetic storage device, the soft magnetic body is formed so as to cover the line either totally or partially, and the anti-ferromagnetic layer is formed on the outer surface of this soft magnetic body. Furthermore, the magneto-resistive element is disposed in the vicinity of the line. Suppose the case where the exchange coupling energy at the interface between the soft magnetic body and the anti-ferromagnetic layer is J (erg/cm2), the saturation magnetization of the soft magnetic body is Ms (emu/cc), and the coercive force of the soft magnetic body is Hc (Oe). Then, the thickness t (cm) of the soft magnetic body is selected to be such that t<J/(Hc·Ms).Type: ApplicationFiled: June 6, 2007Publication date: January 10, 2008Inventors: Susumu Haratani, Tohru Oikawa, Takashi Asatani