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).

  • Publication number: 20040115839
    Abstract: 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: Application
    Filed: November 21, 2003
    Publication date: June 17, 2004
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO.,
    Inventors: Yasunari Sugita, Akihiro Odagawa, Nozomu Matsukawa, Yoshio Kawashima, Yasunori Morinaga
  • Publication number: 20040086752
    Abstract: The present invention provides a magnetoresistive element that has excellent magnetoresistance characteristics over a conventional magnetoresistive element. The magnetoresistive element is produced by a method including heat treatment at 330° C. or more and characterized in that the longest distance from a centerline of a non-magnetic layer to the interfaces between a pair of ferromagnetic layers and the non-magnetic layer is not more than 10 nm. This element can be produced, e.g., by forming an underlying film on a substrate, heat-treating the underlying film at 400° C. or more, decreasing surface roughness by irradiating the surface of the underlying film with an ion beam, and forming the ferromagnetic layers and the non-magnetic layer. The longest distance is reduced relatively even when M1 (at least one element selected from Tc, Re, Ru, Os, Rh, Ir, Pd, Pt, Cu, Ag and Au) is added to the ferromagnetic layers in the range of 2 nm from the interfaces with the non-magnetic layer.
    Type: Application
    Filed: October 24, 2003
    Publication date: May 6, 2004
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO.
    Inventors: Nozomu Matsukawa, Akihiro Odagawa, Yasunari Sugita, Mitsuo Satomi, Yoshio Kawashima, Masayoshi Hiramoto
  • Publication number: 20040085807
    Abstract: 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: Application
    Filed: October 24, 2003
    Publication date: May 6, 2004
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita, Yoshio Kawashima
  • Publication number: 20040080876
    Abstract: 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: Application
    Filed: October 22, 2003
    Publication date: April 29, 2004
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO.
    Inventors: Yasunari Sugita, Akihiro Odagawa, Nozomu Matsukawa
  • Patent number: 6717780
    Abstract: A magneto-resistive element includes a vertical current type magneto-resistive element; a first conductor for causing a current to flow into the vertical current type magneto-resistive element; and a second conductor for causing the current to flow out of the vertical current type magneto-resistive element. The first conductor generates a first magnetic field based on the current. The second conductor generates a second magnetic field based on the current. The first conductor and the second conductor are located so that the first magnetic field and the second magnetic field act as a bias magnetic field applied on the vertical current type magneto-resistive element.
    Type: Grant
    Filed: October 2, 2001
    Date of Patent: April 6, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
  • Publication number: 20040057295
    Abstract: The present invention provides a magnetic memory device that includes the following: 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 at least one ferromagnetic member forms a magnetic gap at a position where the magnetic flux passes through the magnetoresistive element. The following relationships are established: a) Ml≦2Lg; b) at least one selected from Lw/Ly≦5 and Ly/Lt≧5; and c) Ly≦1.0 &mgr;m, where Ml is a length of the magnetoresistive element that is measured in a direction parallel to the magnetic gap, Lg is a length of the magnetic gap, Lt is a thickness of the ferromagnetic member, Lw is a length of the ferromagnetic member in the direction of drawing of the conductive wire, and Ly is a length of a path traced by the magnetic flux in the ferromagnetic member.
    Type: Application
    Filed: July 8, 2003
    Publication date: March 25, 2004
    Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita
  • Patent number: 6708390
    Abstract: The present invention provides a magnetoresistive element that can suppress the characteristic degradation even after high-temperature heat treatment, specifically at 400° C. to 450° C. This element is manufactured by a method that includes the following processes in the indicated order: a film formation process for forming at least a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer on a substrate; a preheat process at 330° C. to 380° C. for not less than 60 minutes; and a heat treatment process at 400° C. to 450° C. This element has a resistance value that changes with a change in relative angle formed by the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer.
    Type: Grant
    Filed: April 23, 2003
    Date of Patent: March 23, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yoshio Kawashima, Akihiro Odagawa, Nozomu Matsukawa, Yasunari Sugita, Yasunori Morinaga
  • Publication number: 20040052006
    Abstract: A magnetoresistance element, wherein a first electric conductor is so formed as to contact almost the center of the surface opposite to a non-magnetic layer of a first ferromagnetic layer so formed as to sandwich, along with a second ferromagnetic layer, the non-magnetic layer, and an insulator so formed as to cover at least the side surface of the first ferromagnetic layer and the non-magnetic layer is formed so as to cover the peripheral edge of the surface of the first ferromagnetic layer, whereby it is possible to prevent a leakage current from flowing from the first electric conductor to a second electric conductor along the side surfaces of the first ferromagnetic layer, the non-magnetic layer and the second ferromagnetic layer, and to make uniform a bias current running from the first electric conductor to the second electric conductor to thereby restrict variations in magnetoresistance characteristics such as MR value and junction resistance.
    Type: Application
    Filed: July 29, 2003
    Publication date: March 18, 2004
    Inventors: Akihiro Odagawa, Masayoshi Hiramoto, Nozomu Matsukawa, Masahiro Deguchi
  • Publication number: 20040047190
    Abstract: The present invention provides a magnetoresistive memory device including 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. The present invention uses a plurality of conductive wires to apply a magnetic field to a single magnetoresistive element, thereby achieving high-speed response and suppressing crosstalk.
    Type: Application
    Filed: June 26, 2003
    Publication date: March 11, 2004
    Inventors: Akihiro Odagawa, Masayoshi Hiramoto, Nozomu Matsukawa
  • Publication number: 20040027733
    Abstract: 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.
    Type: Application
    Filed: June 27, 2003
    Publication date: February 12, 2004
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
    Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Yasunari Sugita, Mitsuo Satomi, Yoshio Kawashima
  • Publication number: 20030211360
    Abstract: Magnetic film comprising a substantially crystalline magnetic layer and an intermediate layer alternately formed in contact with each other, wherein the magnetic layer has composition (M1&agr;1&bgr;1)100-&dgr;1A1&dgr;1 (&agr;1, &bgr;1, and &dgr;1 represent % by atomic weight; M1 is at least one of Fe, Co, and Ni; X1 is at least one of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding M1; and A1 is at least one of 0 and N), wherein:
    Type: Application
    Filed: May 30, 2003
    Publication date: November 13, 2003
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Hiroshi Sakakima
  • Publication number: 20030196316
    Abstract: The present invention provides a magnetoresistive element that can suppress the characteristic degradation even after high-temperature heat treatment, specifically at 400° C. to 450° C. This element is manufactured by a method that includes the following processes in the indicated order: a film formation process for forming at least a first ferromagnetic layer, a second ferromagnetic layer, and a non-magnetic layer on a substrate; a preheat process at 330° C. to 380° C. for not less than 60 minutes; and a heat treatment process at 400° C. to 450° C. This element has a resistance value that changes with a change in relative angle formed by the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer.
    Type: Application
    Filed: April 23, 2003
    Publication date: October 23, 2003
    Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO.
    Inventors: Yoshio Kawashima, Akihiro Odagawa, Nozomu Matsukawa, Yasunari Sugita, Yasunori Morinaga
  • Publication number: 20030197505
    Abstract: A magnetoresistance effect element includes a free layer, in which a magnetization direction thereof is easily rotated in response to an external magnetic field, a first non-magnetic layer, and a first pinned layer provided on a side opposite to the free layer of the first non-magnetic layer, in which a magnetization direction of the first pinned layer is not easily rotated in response to the external magnetic field. At least one of the first pinned layer and the free layer includes a first metal magnetic film contacting the first non-magnetic layer, and a first oxide magnetic film.
    Type: Application
    Filed: March 21, 2003
    Publication date: October 23, 2003
    Applicant: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hiroshi Sakakima, Yasunari Sugita, Mitsuo Satomi, Yasuhiro Kawawake, Masayoshi Hiramoto, Nozomu Matsukawa
  • Publication number: 20030193758
    Abstract: A magneto-resistive element includes a magnetic substrate; a magnetic layer; and a non-magnetic layer provided between the magnetic substrate and the magnetic layer.
    Type: Application
    Filed: May 20, 2003
    Publication date: October 16, 2003
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Hideaki Adachi, Kenji Iijima, Hiroshi Sakakima, Yasunari Sugita
  • Patent number: 6632520
    Abstract: Magnetic film comprising a substantially crystalline magnetic layer and an intermediate layer alternately formed in contact with each other, wherein the magnetic layer has composition (M1&agr;1X1&bgr;1)100−&dgr;1A1&dgr;1 (&agr;1, &bgr;1, and &dgr;1 represent % by atomic weight; M1 is at least one of Fe, Co, and Ni; X1 is at least one of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, and transition metals excluding M1; and A1 is at least one of O and N), wherein: 0.1≦&bgr;1≦12 &agr;1+&bgr;1=100 0<&dgr;1≦10; the intermediate layer has composition (M2&agr;2X2&bgr;2)100−&dgr;2A2&dgr;2 (&agr;2, &bgr;2, and &dgr;2 represent % by atomic weight; M2 is at least one of Fe, Co, and Ni; X2 is at least one of Mg, Ca, Sr, Ba, Si, Ge, Sn, Al, Ga, Ge and transition metals excluding the M2; and A2 is O), wherein: 0.1≦&bgr;2≦80 &agr;2+&bgr;2=100 &dgr;1≦&dgr;2≦67.
    Type: Grant
    Filed: September 2, 1999
    Date of Patent: October 14, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Hiroshi Sakakima
  • Publication number: 20030184921
    Abstract: 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 X1bX2cX3d (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: Application
    Filed: February 19, 2003
    Publication date: October 2, 2003
    Inventors: Yasunari Sugita, Masayoshi Hiramoto, Nozomu Matsukawa, Mitsuo Satomi, Yoshio Kawashima, Akihiro Odagawa
  • Publication number: 20030179071
    Abstract: The present invention provides a tunnel magnetoresistive (TMR) element that increases a MR ratio and suppresses the unevenness in resistance. In an embodiment of the present invention, a surface property-controlling layer is arranged between the substrate and the tunnel layer. In another embodiment, at least one of the magnetic layers sandwiching the tunnel layer has an oriented crystal plane other than the closest packed plane. In still another embodiment, the at least one of the magnetic layers includes a magnetic element and a non-magnetic element and has an average electron number of 23.5 to 25.5 or 26.5 to 36. In still another embodiment, the TMR element includes an excess-element capturing layer. This layer includes an alloy or a compound that contains the excess element. The content of the excess element in the capturing layer is higher than those in the magnetic layers.
    Type: Application
    Filed: February 7, 2003
    Publication date: September 25, 2003
    Inventors: Masayoshi Hiramoto, Nozomu Matsukawa, Akihiro Odagawa, Kenji Iijima, Hiroshi Sakakima
  • Publication number: 20030142539
    Abstract: The present invention provides 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: Application
    Filed: October 18, 2002
    Publication date: July 31, 2003
    Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Akihiro Odagawa, Mitsuo Satomi, Yasunari Sugita
  • Patent number: 6590268
    Abstract: A magnetic control device including an antiferromagnetic layer, a magnetic layer placed in contact with one side of the antiferromagnetic layer, and an electrode placed in contact with another side of the antiferromagnetic layer, wherein the direction of the magnetization of the magnetic layer is controlled by voltage applied between the magnetic layer and the electrode. In particular, when an additional magnetic layer is further laminated on the magnetic layer placed in contact with the antiferromagnetic layer via a non-magnetic layer, the direction of the magnetization of the controlled magnetic layer can be detected as a change in the electric resistance. Since such a magnetic control device, in principle, responds to the electric field or magnetic field, it forms a magnetic component capable of detecting an electric signal or a magnetic signal. In this case, the direction of the magnetization basically is maintained until the next signal is detected, so that such a device also can form an apparatus.
    Type: Grant
    Filed: March 9, 2001
    Date of Patent: July 8, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Hideaki Adachi, Akihiro Odagawa, Masayoshi Hiramoto, Nozomu Matsukawa, Hiroshi Sakakima
  • Patent number: 6588092
    Abstract: Method for producing a magnetic head of a pair of magnetic core halves combined with a nonmagnetic layer therebetween including forming a winding window in at least one of a pair of generally flat oxide magnetic plates, forming at least one underlying layer on each oxide magnetic plate, forming a metal magnetic thin film on the underlying layer containing magnetic crystalline particles having average volume Va and average surface area Sa fulfilling the relationship Sa>about 4.64 Va¾, forming a groove in a body including the oxide magnetic plate, underlying layer and metal magnetic thin film, and combining the body with another body including an oxide magnetic plate and a metal magnetic thin film with a nonmagnetic layer therebetween, where the metal magnetic thin film is formed in such a manner to prevent the oxide magnetic plates from cracking due to internal stress generated in the metal magnetic thin film.
    Type: Grant
    Filed: December 28, 2001
    Date of Patent: July 8, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Nozomu Matsukawa, Masayoshi Hiramoto, Hiroshi Sakakima, Koichi Osano, Eisuke Sawai