Patents by Inventor Nozomu Matsukawa
Nozomu Matsukawa 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: 6977799Abstract: The present invention provides a magnetic head having improved characteristics, using a magnetoresistive device in which current flows across the film plane such as a TMR device. In a first magnetic head of the present invention, when the area of a non-magnetic layer is defined as a device cross-section area, and the area of a yoke is defined as a yoke area, viewed along the direction perpendicular to the surface of the substrate over which the yoke and the magnetoresistive device are formed, then the device cross-section area is not less than 30% of the yoke area, so that a resistance increase of the device cross-section area is suppressed. In a second magnetic head of the present invention, a magnetoresistive device is formed on a substrate, and a yoke is provided above a non-magnetic layer constituting the device.Type: GrantFiled: July 22, 2004Date of Patent: December 20, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
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Patent number: 6954372Abstract: A magnetic memory device that includes a magnetoresistive element, a conductive wire for generating magnetic flux that changes a resistance value of the magnetoresistive element, and at least one ferromagnetic member through which the magnetic flux passes. The ferromagnetic member forms a magnetic gap at a position where the magnetic flux passes through the magnetoresistive element. A length of the magnetoresistive element that is measured in a direction parallel to the magnetic gap is less than or equal to twice the length of the magnetic gap. A length of a path traced by the magnetic flux in the ferromagnetic member is less than or equal to 1.0 ?m. The length of the path is also greater than or equal to five times the thickness of the ferromagnetic member and/or is greater than or equal to a length of the ferromagnetic member in the direction of the drawing of the conductive wire divided by five.Type: GrantFiled: January 18, 2002Date of Patent: October 11, 2005Assignee: Matsushita Electric Co., Ltd.Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita
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Patent number: 6950333Abstract: A magnetic memory of the present invention includes two or more memory layers and two or more tunnel layers that are stacked in the thickness direction of the layers. The two or more memory layers are connected electrically in series. A group of first layers includes at least one layer selected from the two or more memory layers. A group of second layers includes at least one layer selected from the two or more memory layers. A resistance change caused by magnetization reversal in the group of first layers differs from a resistance change caused by magnetization reversal in the group of second layers.Type: GrantFiled: October 24, 2003Date of Patent: September 27, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita, Yoshio Kawashima
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Patent number: 6943041Abstract: The present invention provides a method for producing a magnetoresistive element including a tunnel insulating layer, and a first magnetic layer and a second magnetic layer that are laminated so as to sandwich the tunnel insulating layer, wherein a resistance value varies depending on a relative angle between magnetization directions of the first magnetic layer and the second magnetic layer.Type: GrantFiled: November 21, 2003Date of Patent: September 13, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Yasunari Sugita, Akihiro Odagawa, Nozomu Matsukawa, Yoshio Kawashima, Yasunori Morinaga
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Publication number: 20050174700Abstract: The present invention provides a magnetic head having improved characteristics, using a magnetoresistive device in which current flows across the film plane such as a TMR device. In a first magnetic head of the present invention, when the area of a non-magnetic layer is defined as a device cross-section area, and the area of a yoke is defined as a yoke area, viewed along the direction perpendicular to the surface of the substrate over which the yoke and the magnetoresistive device are formed, then the device cross-section area is not less than 30% of the yoke area, so that a resistance increase of the device cross-section area is suppressed. In a second magnetic head of the present invention, a magnetoresistive device is formed on a substrate, and a yoke is provided above a non-magnetic layer constituting the device.Type: ApplicationFiled: July 22, 2004Publication date: August 11, 2005Applicant: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
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Patent number: 6917492Abstract: A magnetoresistive element includes a pair of ferromagnetic layers and a non-magnetic layer arranged between the ferromagnetic layers. At least one of the ferromagnetic layers has a composition expressed by (MxLy)100-zRz at the interface with the non-magnetic layer. The non-magnetic layer includes at least one element selected from the group consisting of B, C, N, O, and P. Here, M is FeaCobNic, L is at least one element selected from the group consisting of Pt, Pd, Ir, and Rh, R is an element that has a lower free energy to form a compound with the element of the non-magnetic layer that is at least one selected from the group consisting of B, C, N, O, and P than does any other element included in the composition as M or L, and a, b, c, x, y, and z satisfy a+b+c=100, a?30, x+y=100, 0<y?35, and 0.1?z?20. This element can provide a high MR ratio. A method for manufacturing a magnetoresistive element includes a first heat treatment process at 200° C. to 330° C.Type: GrantFiled: June 27, 2003Date of Patent: July 12, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Yasunari Sugita, Mitsuo Satomi, Yoshio Kawashima
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Publication number: 20050135020Abstract: The present invention provides a magnetoresistive (MR) element that is excellent in MR ratio and thermal stability and includes at least one magnetic layer including a ferromagnetic material M-X expressed by M100-aXa. Here, M is at least one selected from Fe, Co and Ni, X is expressed by X1bX2c,X3d (X1 is at least one selected from Cu, Ru, Rh, Pd, Ag, Os, Ir, Pt and Au, X2 is at least one selected from Al, Sc, Ti, V, Cr, Mn, Ga, Ge, Y, Zr, Nb, Mo, Hf, Ta, W, Re, Zn and lanthanide series elements, and X3 is at least one selected from Si, B, C, N, O, P and S), and a, b, c and d satisfy 0.05?a?60, 0?b?60, 0?c?30, 0?d?20, and a=b+c+d.Type: ApplicationFiled: February 16, 2005Publication date: June 23, 2005Applicant: Matsushita Electric Industrial Co., Ltd.Inventors: Yasunari Sugita, Masayoshi Hiramoto, Nozomu Matsukawa, Mitsuo Satomi, Yoshio Kawashima, Akihiro Odagawa
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Patent number: 6887717Abstract: A magnetoresistive device including a high-resistivity layer (13), a first magnetic layer (12) and a second magnetic layer (14), the first magnetic layer (12) and the second magnetic layer (14) being arranged so as to sandwich the high-resistivity layer (13), wherein the high-resistivity layer (13) is a barrier for passing tunneling electrons between the first magnetic layer (12) and the second magnetic layer (14), and contains at least one element LONC selected from oxygen, nitrogen and carbon; at least one layer A selected from the first magnetic layer (12) and the second magnetic layer (14) contains at least one metal element M selected from Fe, Ni and Co, and an element RCP different from the metal element M; and the element RCP combines with the element LONC more easily in terms of energy than the metal element M. Accordingly, a novel magnetoresistive device having a low junction resistance and a high MR can be obtained.Type: GrantFiled: August 19, 2002Date of Patent: May 3, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Hiroshi Sakakima, Hideaki Adachi, Akihiro Odagawa
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Patent number: 6878979Abstract: A spin switch that can be driven with voltage. This spin switch includes the following: a ferromagnetic material; a magnetic semiconductor magnetically coupled to the ferromagnetic material; an antiferromagnetic material magnetically coupled to the magnetic semiconductor; and an electrode connected to the magnetic semiconductor via an insulator. A change in the electric potential of the electrode causes the magnetic semiconductor to make a reversible transition between a ferromagnetic state and a paramagnetic state. When the magnetic semiconductor is changed to the ferromagnetic state, the ferromagnetic material is magnetized in a predetermined direction due to the magnetic coupling with the magnetic semiconductor.Type: GrantFiled: January 18, 2002Date of Patent: April 12, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita
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Patent number: 6861940Abstract: A magnetoresistive element of the present invention includes a multilayer structure that includes a non-magnetic layer (3) and a pair of ferromagnetic layers (1, 2) stacked on both sides of the non-magnetic layer (3). A resistance value differs depending on a relative angle between the magnetization directions of the ferromagnetic layers (1, 2) at the interfaces with the non-magnetic layer (3). The composition of at least one of the ferromagnetic layers (1, 2) in a range of 2 nm from the interface with the non-magnetic layer (3) is expressed by (MxOy)1-zZz, where Z is at least one element selected from the group consisting of Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, and Au, M is at least one element selected from the group consisting of elements other than Z and O and includes a ferromagnetic metal, and x, y, and z satisfy 0.33<y/x<1.33, 0<x, 0<y, and 0?z?0.4. This magnetoresistive element can have excellent heat resistance and magnetoresistance characteristics.Type: GrantFiled: December 10, 2003Date of Patent: March 1, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Nozomu Matsukawa, Akihiro Odagawa, Yasunari Sugita, Mitsuo Satomi, Yoshio Kawashima
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Patent number: 6842317Abstract: A magnetoresistive element includes a multilayer film configuration including: a tunnel insulation layer; and a pair of magnetic layers that are laminated with the tunnel insulation layer interposed therebetween. A resistance value of the magnetoresistive element varies with a relative angle between magnetic orientations of both of the magnetic layers, and at least one of the magnetic layers includes a magnetic film having a thermal expansion coefficient not greater than a value obtained by adding 2×10?6/K to a thermal expansion coefficient of the tunnel insulation layer. The thus configured magnetoresistive element can exert excellent thermal stability. The use of such a magnetoresistive element can realize a magnetic head, a magnetic memory element and a magnetic recording apparatus with excellent thermal stability.Type: GrantFiled: October 22, 2003Date of Patent: January 11, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Yasunari Sugita, Akihiro Odagawa, Nozomu Matsukawa
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Patent number: 6839273Abstract: A magnetic switching device is provided, which has a configuration different from that of a conventional example and is capable of enhancing an energy conversion efficiency for changing the magnetized state of a magnetic substance. A magnetic memory using the magnetic switching device also is provided The magnetic switching device includes a magnetic layer, a transition layer magnetically coupled to the magnetic layer, and a carrier supplier including at least one selected from metal and a semiconductor. The transition layer and the carrier supplier are placed in such a manner that a voltage can be applied between the transition layer and the carrier supplier. The transition layer undergoes a non-ferromagnetism—ferromagnetism transition by the application of a voltage, and the magnetized state of the magnetic layer is changed by the transition of the transition layer.Type: GrantFiled: February 20, 2004Date of Patent: January 4, 2005Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Akihiro Odagawa, Nozomu Matsukawa, Yasunari Sugita
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Publication number: 20040257712Abstract: The present invention provides a magnetic head having improved characteristics, using a magnetoresistive device in which current flows across the film plane such as a TMR device. In a first magnetic head of the present invention, when the area of a non-magnetic layer is defined as a device cross-section area, and the area of a yoke is defined as a yoke area, viewed along the direction perpendicular to the surface of the substrate over which the yoke and the magnetoresistive device are formed, then the device cross-section area is not less than 30% of the yoke area, so that a resistance increase of the device cross-section area is suppressed. In a second magnetic head of the present invention, a magnetoresistive device is formed on a substrate, and a yoke is provided above a non-magnetic layer constituting the device.Type: ApplicationFiled: July 22, 2004Publication date: December 23, 2004Applicant: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
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Publication number: 20040235202Abstract: The present invention provides a method for producing a magnetoresistive element including a tunnel insulating layer, and a first magnetic layer and a second magnetic layer that are laminated so as to sandwich the tunnel insulating layer, wherein a resistance value varies depending on a relative angle between magnetization directions of the first magnetic layer and the second magnetic layer.Type: ApplicationFiled: June 25, 2004Publication date: November 25, 2004Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.Inventors: Yasunari Sugita, Akihiro Odagawa, Nozomu Matsukawa, Yoshi Kawashima, Yasunori Morinaga
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Patent number: 6798620Abstract: A magnetic head including a magnetic substrate for operating as a first electrode, a multi-layer film formed on a portion of the surface of the magnetic substrate an inter-layer insulating layer provided to cover side surfaces of the multi-layer film, a flux guide formed on surfaces of the multi-layer film and inter-layer insulating layers, a non-magnetic conductive layer formed on a surface of the flux guide, and a second electrode formed on a surface of the non-magnetic conductive layer, in which the multi-layer film includes a first magnetic layer formed on a portion of the surface of the magnetic substrate and includes a fixed layer, and a second magnetic layer including a non-magnetic layer formed on a surface of the first magnetic layer and a free layer formed on a surface of the non-magnetic layer.Type: GrantFiled: May 20, 2003Date of Patent: September 28, 2004Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Hideaki Adachi, Kenji Iijima, Hiroshi Sakakima, Yasunari Sugita
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Patent number: 6785100Abstract: The present invention provides a magnetic head having improved characteristics, using a magnetoresistive device in which current flows across the film plane such as a TMR device. In a first magnetic head of the present invention, when the area of a non-magnetic layer is defined as a device cross-section area, and the area of a yoke is defined as a yoke area, viewed along the direction perpendicular to the surface of the substrate over which the yoke and the magnetoresistive device are formed, then the device cross-section area is not less than 30% of the yoke area, so that a resistance increase of the device cross-section area is suppressed. In a second magnetic head of the present invention, a magnetoresistive device is formed on a substrate, and a yoke is provided above a non-magnetic layer constituting the device.Type: GrantFiled: April 9, 2001Date of Patent: August 31, 2004Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
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Publication number: 20040165428Abstract: A magnetic switching device is provided, which has a configuration different from that of a conventional example and is capable of enhancing an energy conversion efficiency for changing the magnetized state of a magnetic substance. A magnetic memory using the magnetic switching device also is provided. The magnetic switching device includes a magnetic layer, a transition layer magnetically coupled to the magnetic layer, and a carrier supplier including at least one selected from metal and a semiconductor. The transition layer and the carrier supplier are placed in such a manner that a voltage can be applied between the transition layer and the carrier supplier. The transition layer undergoes a non-ferromagnetism-ferromagnetism transition by the application of a voltage, and the magnetized state of the magnetic layer is changed by the transition of the transition layer.Type: ApplicationFiled: February 20, 2004Publication date: August 26, 2004Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.Inventors: Akihiro Odagawa, Nozomu Matsukawa, Yasunari Sugita
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Patent number: 6778427Abstract: A magnetoresistve memory device includes a magnetoresistive element and a wiring for applying a magnetic field to the magnetoresistive element. The wiring includes two or more conductive wires that extend in the same direction. A plurality of conductive wires is used to apply a magnetic field to a single magnetoresistive element, thereby achieving high-speed response and suppressing crosstalk.Type: GrantFiled: June 26, 2003Date of Patent: August 17, 2004Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Akihiro Odagawa, Masayoshi Hiramoto, Nozomu Matsukawa
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Patent number: 6778425Abstract: A magneto-resistive effect memory element according to the present invention includes a first ferromagnetic film; a second ferromagnetic film; a first nonmagnetic film provided between the first ferromagnetic film and the second ferromagnetic film, a first conductive film for generating a magnetic field for causing magnetization inversion in at least one of the first ferromagnetic film and the second ferromagnetic film, the first conductive film not being electrically in contact with the first ferromagnetic film or the second ferromagnetic film; and a second conductive film and a third conductive film for supplying an electric current to the first ferromagnetic film, the first nonmagnetic film, and the second ferromagnetic film. The first ferromagnetic film and the second ferromagnetic film have different magnetization inversion characteristics with respect to the magnetic field, and the first nonmagnetic film contains at least a nitride.Type: GrantFiled: August 22, 2001Date of Patent: August 17, 2004Assignee: Matsushita Electric Industrial Co., Ltd.Inventors: Akihiro Odagawa, Masayoshi Hiramoto, Nozomu Matsukawa, Hideaki Adachi, Hiroshi Sakakima
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Publication number: 20040130431Abstract: A magnetoresistive element of the present invention includes a multilayer structure that includes a non-magnetic layer (3) and a pair of ferromagnetic layers (1, 2) stacked on both sides of the non-magnetic layer (3). A resistance value differs depending on a relative angle between the magnetization directions of the ferromagnetic layers (1, 2) at the interfaces with the non-magnetic layer (3). The composition of at least one of the ferromagnetic layers (1, 2) in a range of 2 nm from the interface with the non-magnetic layer (3) is expressed by (MxOy)1-zZz, where Z is at least one element selected from the group consisting of Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag, and Au, M is at least one element selected from the group consisting of elements other than Z and O and includes a ferromagnetic metal, and x, y, and z satisfy 0.33<y/x<1.33, 0<x, 0<y, and 0≦z≦0.4. This magnetoresistive element can have excellent heat resistance and magnetoresistance characteristics.Type: ApplicationFiled: December 10, 2003Publication date: July 8, 2004Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.Inventors: Nozomu Matsukawa, Akihiro Odagawa, Yasunari Sugita, Mitsuo Satomi, Yoshio Kawashima