Patents by Inventor Yasushi Ogimoto
Yasushi Ogimoto 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: 8411395Abstract: A method for driving a spin valve element, including passing driving current through the spin valve element to generate an oscillation signal, and performing amplitude modulation of the driving current at a frequency lower than the oscillation frequency of oscillation signals. This amplitude modulation can be ON-OFF modulation, and the interval ton in the conducting state of the ON-OFF modulation is made to satisfy the relation ton<D2/?, where ? is the thermal diffusivity of the heat diffusion portion, and D is the thickness of the heat diffusion portion.Type: GrantFiled: August 28, 2008Date of Patent: April 2, 2013Assignee: Fuji Electric Co., Ltd.Inventors: Haruo Kawakami, Yasushi Ogimoto, Eiki Adachi
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Patent number: 8331057Abstract: Examples of an electromagnetic field detecting element according to the present invention includes a substrate, a pair of electrodes, three insulation layers disposed on the substrate and between the electrodes. The three insulation layers are designed to have two or three different dielectric breakdown strength. At least two ballistic current paths are formed between the electrodes. With this structure, it is possible to perform at a room temperature a highly efficient electromagnetic field detection utilizing Aharonov-Bohm effect or Aharonov-Casher effect.Type: GrantFiled: September 25, 2006Date of Patent: December 11, 2012Assignee: Sharp Kabushiki KaishaInventors: Shintaro Miyanishi, Yasushi Ogimoto, Yoshiteru Murakami, Kunio Kojima
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Publication number: 20120268986Abstract: The present invention provides a magnetic memory element that has a spin valve structure formed using a free layer, a non-magnetic layer, and a pinned layer. The free layer has a three-layer structure having a first magnetic layer, an intermediate layer, and a second magnetic layer arranged in this order viewed from the non-magnetic layer. The first magnetic layer is made of a ferromagnetic material. The intermediate layer is made of a non-magnetic material. The second magnetic layer is made of an N-type ferromagnetic material having a magnetic compensation point in the temperature range where a memory storage operation can be available. The magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are parallel to each other at the temperature lower than the magnetic compensation point Tcomp.Type: ApplicationFiled: August 25, 2009Publication date: October 25, 2012Applicant: FUJI ELECTRIC CO., LTD.Inventor: Yasushi Ogimoto
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Patent number: 8279661Abstract: A magnetic memory element (10) for use in a cross-point type memory is provided with a spin valve structure having a free layer (5), a nonmagnetic layer (4), and a pinned layer (3). The magnetic memory element is also provided with another nonmagnetic layer (6) on one surface of the free layer (5), and furthermore, a magnetic change layer (7) whose magnetic characteristics change depending on temperature so as to sandwich the nonmagnetic layer (6) with the free layer (5). In the magnetic change layer (7), the magnetization intensity increases depending on temperature.Type: GrantFiled: August 28, 2008Date of Patent: October 2, 2012Assignee: Fuji Electric Co., Ltd.Inventors: Yasushi Ogimoto, Haruo Kawakami
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Patent number: 8274820Abstract: In order to obtain a memory cell of size 4 F2 to realize cross-point type memory, a magnetic memory element is used having a spin valve structure including a free layer 5, nonmagnetic layer 4, and layer 3. The layer or the free layer includes an N-type ferrimagnetic material, and the magnetic compensation point of the N-type ferrimagnetic material is lower than the temperature reached by the layer when a certain write pulse is applied to control the combination of magnetizations of the free layer and layer, and higher than the temperature reached by the layer when another write pulse is applied. These write pulses can have the same polarity.Type: GrantFiled: August 28, 2008Date of Patent: September 25, 2012Assignee: Fuji Electric Co., Ltd.Inventor: Yasushi Ogimoto
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Publication number: 20120230089Abstract: A magnetoresistance element is disclosed. The magnetoresistance element includes a magnetic tunnel junction portion configured by sequentially stacking a perpendicularly magnetized first magnetic body, an insulation layer, and a perpendicularly magnetized second magnetic body. The second magnetic body has a configuration wherein a ferromagnetic layer and a rare earth-transition metal alloy layer are stacked sequentially from the insulation layer side interface. A heat assist layer that heats the second magnetic body with a heat generated based on a current flowing through the magnetic tunnel junction portion is further provided.Type: ApplicationFiled: August 4, 2010Publication date: September 13, 2012Applicant: FUJI ELECTRIC CO., LTD.Inventors: Michiya Yamada, Yasushi Ogimoto
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Publication number: 20120187945Abstract: A non-contact current censor includes a spin valve structure (2), an electrical unit (4) that applies a varying current to the spin valve structure (2), and a resistance reading unit that electrically reads out a resistance value of the spin valve structure (2). When a current-induced magnetic field is detected, a coercive force of a free layer (14) is configured to be larger than the current-induced magnetic field as a detection target, and the electrical unit (4) allows the magnetization directions of a pinned layer (12) and the free layer (14) to transition between a mutually parallel state and a mutually anti-parallel state by applying the current to the spin valve structure (2). The resistance reading unit (5) detects a threshold value corresponding to the transition.Type: ApplicationFiled: April 12, 2010Publication date: July 26, 2012Applicant: FUJI ELECTRIC CO. LTDInventor: Yasushi Ogimoto
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Publication number: 20120134201Abstract: A magnetic memory element and a method of driving such an element are disclosed. The magnetic memory element has a magnetic tunnel junction portion with a spin-valve structure having a perpendicular magnetization free layer formed of a perpendicular magnetization film, a perpendicular magnetization pinned layer formed of a perpendicular magnetization film, and a nonmagnetic layer sandwiched between the perpendicular magnetization free layer and the perpendicular magnetization pinned layer, and records information by application of an electric pulse to the magnetic tunnel junction portion. An in-plane magnetization film, interposed in the path of the electric pulse, is disposed in the magnetic tunnel junction portion. The in-plane magnetization film is configured so as to exhibit antiferromagnetic (low-temperature)-ferromagnetic (high-temperature) phase transitions depending on temperature changes based on application of the electric pulse to the magnetic tunnel junction portion.Type: ApplicationFiled: May 14, 2010Publication date: May 31, 2012Applicant: FUJI ELECTRONIC CO., LTDInventor: Yasushi Ogimoto
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Publication number: 20120075922Abstract: A magnetic memory element capable of maintaining high thermal stability (retention characteristics) while reducing a writing current. The magnetic memory element includes a magnetic tunnel junction having a first magnetic body including a perpendicular magnetization film, an insulating layer, and a second magnetic body serving as a storage layer including a perpendicular magnetization film, which are sequentially stacked. A thermal expansion layer is disposed in contact with the magnetic tunnel junction portion. The second magnetic body is deformed in a direction in which the cross section thereof increases or decreases by the thermal expansion or contraction of the thermal expansion layer due to the flow of a current, thereby reducing a switching current threshold value required to change the magnetization direction.Type: ApplicationFiled: March 17, 2010Publication date: March 29, 2012Applicant: Fuji Electric Co., Ltd.Inventors: Michiya Yamada, Yasushi Ogimoto
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Publication number: 20120012954Abstract: An object of the invention is to ensure the thermal stability of magnetization even when a magnetic memory element is miniaturized. A magnetic memory element includes a first magnetic layer (22), an insulating layer (21) that is formed on the first magnetic layer (22), and a second magnetic layer (20) that is formed on the insulating layer (21). At least one of the first magnetic layer (22) and the second magnetic layer (20) is strained and deformed so as to be elongated in an easy magnetization axis direction of the magnetic layer (22) or (20) or compressive strain (101) remains in any direction in the plane of at least one of the first magnetic layer and the second magnetic layer.Type: ApplicationFiled: July 8, 2009Publication date: January 19, 2012Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.Inventors: Michiya Yamada, Yasushi Ogimoto
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Publication number: 20110310660Abstract: A magnetic memory element having a memory cell of size 4F2 is provided that realizes a crosspoint-type memory. In the magnetic memory element, a first magnetic layer, a third magnetic layer (spin polarization enhancement layer), an intermediate layer, a fourth magnetic layer (spin polarization enhancement layer), and a second magnetic layer are stacked in order. The intermediate layer is made of an insulating material or a nonmagnetic material. The second magnetic layer is composed of a ternary alloy of gadolinium, iron and cobalt, a binary alloy of gadolinium and cobalt, or a binary alloy of terbium and cobalt. Alternatively, the first magnetic layer is composed of a ternary alloy of terbium, iron and cobalt, or a binary alloy of terbium and cobalt.Type: ApplicationFiled: June 21, 2011Publication date: December 22, 2011Applicant: FUJI ELECTRIC CO., LTD.Inventors: Michiya Yamada, Yasushi Ogimoto
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Publication number: 20110188297Abstract: In accordance with one aspect of the invention, a magnetic memory element records information in a spin valve structure having a free layer, a pinning layer, and a nonmagnetic layer sandwiched therebetween. The magnetic memory element further has, on the free layer, a separate nonmagnetic layer and a magnetic change layer having magnetic characteristics which change according to temperature. Multiple cutouts, including one cutout with a different shape, are provided in a peripheral portion of the spin valve structure. A method of driving the magnetic memory element is characterized in that information is recorded by applying unipolar electric pulses.Type: ApplicationFiled: September 5, 2008Publication date: August 4, 2011Inventors: Yasushi Ogimoto, Haruo Kawakami
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Patent number: 7978047Abstract: A variable resistance element comprises a variable resistor of strongly-correlated material sandwiched between two metal electrodes, and the electric resistance between the metal electrodes varies when a voltage pulse is applied between the metal electrodes. Such a switching operation as the ratio of electric resistance between low and high resistance states is high can be attained by designing the metal electrodes and variable resistor appropriately based on a definite switching operation principle. Material and composition of the first electrode and variable resistor are set such that metal insulator transition takes place on the interface of the first electrode in any one of two metal electrodes and the variable resistor by applying a voltage pulse. Two-phase coexisting phase of metal and insulator phases can be formed in the vicinity of the interface between the variable resistor and first electrode by the work function difference between the first electrode and variable resistor.Type: GrantFiled: August 8, 2006Date of Patent: July 12, 2011Assignees: Sharp Kabushiki Kaisha, National Science and TechnologyInventors: Yasunari Hosoi, Shigeo Ohnishi, Yasushi Ogimoto, Takashi Oka, Naoto Nagaosa, Yoshinori Tokura
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Publication number: 20110143166Abstract: A spin-valve element has a pair of ferromagnetic layers having mutually different coercive forces, sandwiching an insulating layer or a nonmagnetic layer therebetween. The in-plane shape of the spin-valve element is substantially circular in shape but is provided, in the peripheral portion, with a plurality of cutouts NS, NW, NE, NN. Preferably, the shape of at least one cutout be made different from that of others. Moreover, a storage device that employs such a spin-valve element is provided.Type: ApplicationFiled: September 5, 2008Publication date: June 16, 2011Inventors: Haruo Kawakami, Yasushi Ogimoto
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Publication number: 20110102939Abstract: Provided is a spin valve element capable of performing multi-value recording, which includes a pair of ferromagnetic layers having different coercivities from each other, and sandwiching an insulating layer or a non-magnetic layer. The ferromagnetic layer having the smaller coercivity has a substantially circular in-plane profile, and a plurality of island-shaped non-magnetic portions IN, IE, IW, and IS are included. In addition, a storage device is manufactured by using such a spin valve element.Type: ApplicationFiled: September 5, 2008Publication date: May 5, 2011Inventors: Haruo Kawakami, Yasushi Ogimoto
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Patent number: 7924609Abstract: A spin valve element driving method, and a spin valve element employing such a method, for causing microwave oscillation in a spin valve element. The spin valve element includes an intermediate layer and a pair of ferromagnetic layers including a fixed layer and a free layer sandwiching the intermediate layer, the fixed layer having a higher coercivity than the free layer, and being magnetized in a direction substantially perpendicular to a film plane thereof. The method includes a driving step of passing current from one of the pair of ferromagnetic layers to the other through the intermediate layer.Type: GrantFiled: August 28, 2008Date of Patent: April 12, 2011Assignee: Fuji Electric Holdings Co., Ltd.Inventors: Haruo Kawakami, Yasushi Ogimoto
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Publication number: 20110063899Abstract: In order to obtain a memory cell of size 4 F2 to realize cross-point type memory, a magnetic memory element is used having a spin valve structure including a free layer 5, nonmagnetic layer 4, and layer 3. The layer or the free layer includes an N-type ferrimagnetic material, and the magnetic compensation point of the N-type ferrimagnetic material is lower than the temperature reached by the layer when a certain write pulse is applied to control the combination of magnetizations of the free layer and layer, and higher than the temperature reached by the layer when another write pulse is applied. These write pulses can have the same polarity.Type: ApplicationFiled: August 28, 2008Publication date: March 17, 2011Applicant: FUJI ELECTRIC HOLDINGS CO., LTDInventor: Yasushi Ogimoto
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Patent number: 7880502Abstract: A logic circuit with a simple configuration and good current efficiency is provided. The logic circuit includes a two-terminal bistable switching element (1) having characteristics which maintain states, a first switching element (25) one end of which is connected to one terminal of the two-terminal bistable switching element (1), a second switching element (29) one end of which is connected to the other terminal of the two-terminal bistable switching element (1) via a resistance element (27), and first and second pulse input terminals (33, 37) respectively connected to the one terminal and the other terminal of the two-terminal bistable switching element (1). A bias voltage is applied across the other end of the first switching element (25) and the other end of the second switching element (27), and a trigger pulse is input from the first and second pulse input terminals (33, 37).Type: GrantFiled: August 25, 2008Date of Patent: February 1, 2011Assignee: Fuji Electric Holdings Co., Ltd.Inventors: Haruo Kawakami, Yasushi Ogimoto
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Publication number: 20100308946Abstract: A spin valve element driving method, and a spin valve element employing such a method, for causing microwave oscillation in a spin valve element. The spin valve element includes an intermediate layer and a pair of ferromagnetic layers including a fixed layer and a free layer sandwiching the intermediate layer, the fixed layer having a higher coercivity than the free layer, and being magnetized in a direction substantially perpendicular to a film plane thereof. The method includes a driving step of passing current from one of the pair of ferromagnetic layers to the other through the intermediate layer.Type: ApplicationFiled: August 28, 2008Publication date: December 9, 2010Applicant: FUJI ELECTRONIC HOLDINGS CO., LTD.Inventors: Haruo Kawakami, Yasushi Ogimoto
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Publication number: 20100297475Abstract: A spin valve element including an insulating layer or a nonmagnetic layer sandwiched by first and second ferromagnetic layers, and a porous layer having a plurality of minute holes placed in contact with one of the ferromagnetic layers, or near one of the ferromagnetic layer with another intervening layer therebetween. The first ferromagnetic layer is electrically connectable through the minute holes of the porous layer, and the second ferromagnetic layer is also electrically connectable.Type: ApplicationFiled: August 28, 2008Publication date: November 25, 2010Applicant: FUJI ELECTRIC HOLDINGS CO., LTD.Inventors: Haruo Kawakami, Yasushi Ogimoto, Eiki Adachi