Patents by Inventor Tomohito Mizuno

Tomohito Mizuno 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: 20090059442
    Abstract: A magnetic field detecting element comprises: a stack which includes first, second and third magnetic layers whose magnetization directions change in accordance with an external magnetic field, the second magnetic layer being positioned between the first magnetic layer and the third magnetic layer, a first non-magnetic intermediate layer which is sandwiched between the first magnetic layer and the second magnetic layer, the first non-magnetic intermediate layer producing a magnetoresistance effect between the first magnetic layer and the second magnetic layer, and a second non-magnetic intermediate layer which is sandwiched between the second magnetic layer and the third magnetic layer, the second non-magnetic intermediate layer allowing the second magnetic layer and the third magnetic layer to be exchange-coupled such that magnetization directions thereof are anti-parallel to each other under no magnetic field, the stack being adapted such that sense current flows in a direction that is perpendicular to a fi
    Type: Application
    Filed: March 11, 2008
    Publication date: March 5, 2009
    Applicant: TDK Corporation
    Inventors: Tomohito MIZUNO, Yoshihiro Tsuchiya, Shinji Hara, Koji Shimazawa, Tsutomu Chou
  • Publication number: 20090059443
    Abstract: An MR element includes a stack of layers including a first ferromagnetic layer, a second ferromagnetic layer, and a spacer layer disposed between the first and the second ferromagnetic layer. The stack of layers has an outer surface, and the spacer layer has a periphery located in the outer surface of the stack of layers. The magnetoresistive element further includes an insulating film that touches the periphery of the spacer layer. The spacer layer includes a layer made of an oxide semiconductor composed of an oxide of a first metal. The insulating film includes a contact film that touches the periphery of the spacer layer and that is made of an oxide of a second metal having a Pauling electronegativity lower than that of the first metal by 0.1 or more.
    Type: Application
    Filed: August 27, 2007
    Publication date: March 5, 2009
    Applicant: TDK CORPORATION
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Shinji Hara, Daisuke Miyauchi, Takahiko Machita
  • Patent number: 7499247
    Abstract: A magnetoresistive sensor comprises stacked layers. The stacked layers comprises a first magnetic layer, a second non-magnetic intermediate layer, and a second magnetic layer in which a direction of magnetization is variable depending on an external magnetic field. The first magnetic layer, the second non-magnetic intermediate layer, and the second magnetic layer are stacked in this order to form the stacked layers. The first magnetic layer has a first ferromagnetic layer in which a direction of magnetization is pinned relative to the external magnetic field, a first non-magnetic intermediate layer, and a second ferromagnetic layer in which a direction of magnetization is pinned in a direction opposite to the direction of magnetization of the first ferromagnetic layer. The first ferromagnetic layer, the first non-magnetic intermediate layer, and the second ferromagnetic layer are stacked in this order. A sense current flows through the stacked layers substantially in the direction of stacking.
    Type: Grant
    Filed: February 4, 2005
    Date of Patent: March 3, 2009
    Assignee: TDK Corporation
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20090040662
    Abstract: An MR element includes a free layer having a direction of magnetization that changes in response to an external magnetic field, a pinned layer having a fixed direction of magnetization, and a spacer layer disposed between these layers. The spacer layer includes a first region, a second region and a third region that are each in the form of a layer and that are arranged in a direction intersecting the plane of each of the foregoing layers. The second region is sandwiched between the first region and the third region. The first region and the third region are each composed of an oxide semiconductor, and the second region includes at least a nonmagnetic conductor phase out of the nonmagnetic conductor phase and an oxide semiconductor phase.
    Type: Application
    Filed: August 8, 2007
    Publication date: February 12, 2009
    Applicant: TDK CORPORATION
    Inventors: Tsutomu Chou, Tomohito Mizuno
  • Publication number: 20090002893
    Abstract: The invention provides a giant magneto-resistive effect device (CPP-GMR device) having a CPP (current perpendicular to plane) structure comprising a spacer layer, and a fixed magnetized layer and a free layer stacked one upon another with said spacer layer interposed between them, with a sense current applied in a stacking direction, wherein the free layer functions such that the direction of magnetization changes depending on an external magnetic field, and the spacer layer comprises a first and a second nonmagnetic metal layer, each formed of a nonmagnetic metal material, and a semiconductor oxide layer interposed between the first and the second nonmagnetic metal layer, wherein the semiconductor oxide layer that forms a part of the spacer layer is made of zinc oxide, tin oxide, indium oxide, and indium tin oxide (ITO), the first nonmagnetic metal layer is made of Cu, and the second nonmagnetic metal layer is substantially made of Zn.
    Type: Application
    Filed: June 26, 2007
    Publication date: January 1, 2009
    Applicant: TDK CORPORATION
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Shinji Hara
  • Patent number: 7446983
    Abstract: An MR element comprises: a nonmagnetic conductive layer having two surfaces facing toward opposite directions; a free layer disposed adjacent to one of the surfaces of the nonmagnetic conductive layer, wherein the direction of magnetization in the free layer changes in response to an external magnetic field; and a pinned layer disposed adjacent to the other of the surfaces of the nonmagnetic conductive layer, wherein the direction of magnetization in the pinned layer is fixed. The pinned layer incorporates a first pinned layer, a coupling layer and a second pinned layer. The second pinned layer incorporates first to third magnetic layers each of which is made of a magnetic material. Layered structures each made up of a Cu film, a magnetic film and a Cu film are inserted between the first magnetic layer and the second magnetic layer, and between the second magnetic layer and the third magnetic layer, respectively.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: November 4, 2008
    Assignee: TDK Corporation
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20080226948
    Abstract: A magnetoresistance effect element (MR element) for use in a thin-film magnetic head has a buffer layer, an antiferromagnetic layer, a pinned layer, a spacer layer, a free layer, and a cap layer that are successively stacked. A sense current flows in a direction perpendicular to layer surfaces via a lower shield layer and an upper shield layer. The pinned layer comprises an outer layer having a fixed magnetization direction, a nonmagnetic intermediate layer, and an inner layer in the form of a ferromagnetic layer. The spacer layer comprises a first nonmagnetic metal layer, a semiconductor layer made of ZnO, and a second nonmagnetic metal layer. The inner layer or the outer layer includes a diffusion blocking layer made of an oxide of an element whose electronegativity is equal to or smaller than Zn, e.g., ZnO, TaO, ZrO, MgO, TiO, or HfO, or made of RuO.
    Type: Application
    Filed: March 12, 2007
    Publication date: September 18, 2008
    Inventors: Tomohito MIZUNO, Takahiko MACHITA, Kei HIRATA, Yoshihiro TSUCHIYA, Shinji HARA
  • Publication number: 20080226947
    Abstract: A magnetoresistance effect element includes a pinned layer having a fixed magnetization direction, a free layer having a magnetization direction variable depending on an external magnetic field, and a nonmagnetic spacer layer disposed between the pinned layer and the free layer. The free layer includes a Heusler alloy layer and a magnetostriction reduction layer made of a 4th group element, a 5th group element, or a 6th group element.
    Type: Application
    Filed: March 12, 2007
    Publication date: September 18, 2008
    Inventors: Tomohito MIZUNO, Yoshihiro TSUCHIYA, Kei HIRATA
  • Publication number: 20080218907
    Abstract: A magneto-resistance effect element (MR element) used for a thin film magnetic head is configured by a buffer layer, an anti-ferromagnetic layer, a pinned layer, a spacer layer, a free layer, and a cap layer, which are laminated in this order, and a sense current flows through the element in a direction orthogonal to the layer surface, via a lower shield layer and a upper shield layer. The pinned layer comprises an outer layer in which a magnetization direction is fixed, a non-magnetic intermediate layer, and an inner layer which is a ferromagnetic layer. The spacer layer comprises a first non-magnetic metal layer, a semiconductor layer, and a second non-magnetic metal layer. The first non-magnetic metal layer and the second non-magnetic metal layer comprise CuPt films having a thickness ranging from a minimum of 0.2 nm to a maximum of 2.0 nm, and the Pt content ranges from a minimum of 5 at % to a maximum of 25 at %.
    Type: Application
    Filed: March 6, 2007
    Publication date: September 11, 2008
    Applicant: TDK CORPORATION
    Inventors: Tomohito MIZUNO, Kei HIRATA, Yoshihiro TSUCHIYA, Koji SHIMAZAWA
  • Publication number: 20080204942
    Abstract: A magnetic thin film has a pinned layer whose magnetization direction is fixed with respect to an external magnetic field, a free layer whose magnetization direction is changed according to the external magnetic field, and a spacer layer which is sandwiched between said pinned layer and said free layer. Sense current is configured to flow in a direction that is perpendicular to film surfaces of said pinned layer, said spacer layer, and said free layer. Said spacer layer has a CuZn metal alloy which includes an oxide region, said oxide region consisting of an oxide of any of Al, Si, Cr, Ti, Hf, Zr, Zn, and Mg.
    Type: Application
    Filed: February 23, 2007
    Publication date: August 28, 2008
    Inventors: Takahiko MACHITA, Tomohito MIZUNO, Yoshihiro TSUCHIYA, Daisuke MIYAUCHI, Shinji HARA
  • Publication number: 20080198513
    Abstract: A magnetic thin film has: a pinned layer whose magnetization direction is fixed with respect to an external magnetic field; a free layer whose magnetization direction is changed in accordance with the external magnetic field; and a non-magnetic spacer layer that is sandwiched between said pinned layer and said free layer, wherein sense current is configured to flow in a direction that is perpendicular to film surfaces of said pinned layer, said non-magnetic spacer layer, and said free layer. Said non-magnetic spacer layer has a first layer which includes SnO2, and a pair of second layers which are provided to sandwich said first layer, said second layers being made of a material which exhibits a higher corrosion potential than Sn.
    Type: Application
    Filed: February 20, 2007
    Publication date: August 21, 2008
    Inventors: Shinji HARA, Yoshihiro TSUCHIYA, Tomohito MIZUNO
  • Publication number: 20080174920
    Abstract: The invention provides a giant magneto-resistive effect device (CPP-GMR device) having a CPP (current perpendicular to plane) structure comprising a spacer layer, and a fixed magnetized layer and a free layer stacked one upon another with said spacer layer interleaved between them, with a sense current applied in a stacking direction, wherein the spacer layer comprises a first and a second nonmagnetic metal layer, each formed of a nonmagnetic metal material, and a semiconductor oxide layer interleaved between the first and the second nonmagnetic metal layer, wherein the semiconductor oxide layer that forms a part of the spacer layer is made of indium oxide (In2O3), or the semiconductor oxide layer contains indium oxide (In2O3) as its main component, and an oxide containing a tetravalent cation of SnO2 is contained in the indium oxide that is the main component.
    Type: Application
    Filed: January 24, 2007
    Publication date: July 24, 2008
    Applicant: TDK CORPORATION
    Inventors: Shinji Hara, Kei Hirata, Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno
  • Publication number: 20080170336
    Abstract: The invention provides a giant magneto-resistive effect device (CPP-GMR device) having the CPP (current perpendicular to plane) structure comprising a spacer layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked one upon another with the spacer layer interposed between them, with a sense current applied in a stacking direction, wherein the spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each made of a nonmagnetic metal material, and a semiconductor oxide layer interposed between the first nonmagnetic metal layer and the second nonmagnetic metal layer, the semiconductor oxide layer that forms a part of said spacer layer contains zinc oxide as its main component wherein the main component zinc oxide contains an additive metal, and the additive metal is less likely to be oxidized than zinc.
    Type: Application
    Filed: January 3, 2008
    Publication date: July 17, 2008
    Applicant: TDK Corporation
    Inventors: Yoshihiro TSUCHIYA, Tomohito Mizuno, Kei Hirata, Koji Shimazawa, Shinji Hara
  • Publication number: 20080117554
    Abstract: The invention provides a giant magneto-resistive effect device having a CPP structure comprising a spacer layer, and a fixed magnetization layer and a free layer stacked one upon another with said spacer layer interposed between them, wherein the free layer functions such that its magnetization direction changes depending on an external magnetic field, and the spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each formed of a nonmagnetic metal material, and a semiconductor oxide layer interposed between them, wherein the semiconductor oxide layer forming a part of the spacer layer comprises zinc oxide as a main ingredient, wherein the main ingredient zinc oxide contains at least one selected from among oxides containing a trivalent cation of Al2O3, Ga2O3, In2O3, and B2O3, and a tetravalent cation of TiO2.
    Type: Application
    Filed: November 20, 2007
    Publication date: May 22, 2008
    Applicant: TDK Corporation
    Inventors: Shinji Hara, Kei Hirata, Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno
  • Publication number: 20080112091
    Abstract: A spacer layer of an MR element includes: a nonmagnetic metal layer disposed on a pinned layer; a protection layer disposed on the nonmagnetic metal layer to prevent oxidation or nitriding of the nonmagnetic metal layer; an island-shaped insulating layer disposed on the protection layer; and a coating layer covering these layers. When seen in a direction perpendicular to the top surface of the pinned layer, there are formed in the spacer layer a region where the insulating layer is present and a region where the insulating layer is absent. A thickness of the protection layer taken in at least part of the region where the insulating layer is absent is zero or smaller than a thickness of the protection layer taken in the region where the insulating layer is present.
    Type: Application
    Filed: September 5, 2007
    Publication date: May 15, 2008
    Applicant: TDK CORPORATION
    Inventors: Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno
  • Publication number: 20080112096
    Abstract: The thickness of the semiconductor layer forming a part of the spacer layer is set in the thickness range for a transitional area showing conduction performance halfway between ohmic conduction and semi-conductive conduction in relation to the junction of the semiconductor layer with the first nonmagnetic metal layer and the second nonmagnetic metal layer. This permits the specific resistance of the spacer layer to be greater than that of an ohomic conduction area, so that spin scattering and diffusion depending on a magnetized state increases, resulting in an increase in the MR ratio. The CPP-GMR device can also have a suitable area resistivity (AR) value. If the device can have a suitable area resistivity and a high MR ratio, it is then possible to obtain more stable output power in low current operation than ever before, and extend the service life of the device as well. The device is also lower in resistance than a TMR device, so that significant noise reductions are achievable.
    Type: Application
    Filed: November 5, 2007
    Publication date: May 15, 2008
    Applicant: TDK CORPORATION
    Inventors: Tomohito Mizuno, Yoshihiro Tsuchiya, Kei Hirata
  • Publication number: 20080106827
    Abstract: The invention provides a CPP-GMR device comprising a spacer layer. The spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each formed of a nonmagnetic metal material, and a semiconductor layer interposed between the first nonmagnetic metal layer and the second nonmagnetic metal layer, and further comprises a work function control layer formed between the first nonmagnetic metal layer and the semiconductor layer and/or between the second nonmagnetic metal layer and the semiconductor layer. The semiconductor layer is an n-type semiconductor, and the work function control layer is made of a material having a work function smaller than that of said first nonmagnetic metal layer, and said second nonmagnetic metal layer.
    Type: Application
    Filed: October 31, 2007
    Publication date: May 8, 2008
    Applicant: TDK CORPORATION
    Inventors: Koji SHIMAZAWA, Yoshihiro Tsuchiya, Tomohito Mizuno, Kei Hirata
  • Publication number: 20080100969
    Abstract: In an MR element constituted in such a manner that a pinned layer whose magnetization direction is fixed, a nonmagnetic spacer layer, and a free layer whose magnetization direction is changed according to an external magnetic field, are laminated in this order; the free layer has a multilayer constitution including a magnetic body mixed with an element having 4f electrons at a ratio of 2 at % to 25 at. %. Specifically, the first layer in contact with the spacer layer, the third layer, the fifth layer, and the seventh layer of the free layer are formed by mixing Nd, Sm, Gd, or Tb into CoFe having a ratio of Co less than or equal to 70 at. %. The second layer and the sixth layer of the free layer are formed by mixing Nd, Sm, Gd, or Tb into NiFe having a ratio of Ni greater than or equal to 70 at. % and less than 100 at. %. The third layer of the free layer is Cu. A damping constant of the free layer is greater than 0.018.
    Type: Application
    Filed: October 29, 2007
    Publication date: May 1, 2008
    Inventors: Tomohito MIZUNO, Yoshihiro TSUCHIYA
  • Publication number: 20080100968
    Abstract: The invention provides a giant magneto-resistive effect device (CPP-GMR device) having a CPP (current perpendicular to plane) structure comprising a spacer layer, and a fixed magnetization layer and a free layer stacked one upon another with the spacer layer interposed between them, with a sense current applied in a stacking direction. The free layer functions such that the direction of magnetization changes depending on an external magnetic field. The spacer layer comprises a first nonmagnetic metal layer and a second nonmagnetic metal layer, each made of a nonmagnetic metal material, and a semiconductor layer formed between the first and the second nonmagnetic metal layer. The semiconductor layer is an n-type oxide semiconductor. When the first and second nonmagnetic metal layers are formed in order, the first nonmagnetic metal layer is formed prior to the second nonmagnetic metal layer, and an anti-oxidizing layer is formed between the first and the semiconductor layer.
    Type: Application
    Filed: October 10, 2007
    Publication date: May 1, 2008
    Applicant: TDK CORPORATION
    Inventors: Koji SHIMAZAWA, Yoshihiro Tsuchiya, Tomohito Mizuno, Kei Hirata
  • Publication number: 20080062557
    Abstract: An MR element includes: a free layer having a direction of magnetization that changes in response to a signal magnetic field; a pinned layer having a fixed direction of magnetization; and a spacer layer disposed between these layers. The spacer layer includes a first nonmagnetic metal layer and a second nonmagnetic metal layer each made of a nonmagnetic metal material, and a semiconductor layer that is made of a material containing an oxide semiconductor and that is disposed between the first and second nonmagnetic metal layers. The MR element has a resistance-area product within a range of 0.1 to 0.3?·m2, and the spacer layer has a conductivity within a range of 133 to 432 S/cm.
    Type: Application
    Filed: January 26, 2007
    Publication date: March 13, 2008
    Applicant: TDK CORPORATION
    Inventors: Yoshihiro Tsuchiya, Kei Hirata, Tomohito Mizuno, Koji Shimazawa