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: 20080052896
    Abstract: A free layer functions such that a magnetization direction changes depending on an external magnetic field, and is made up of a multilayer structure including a first Heusler alloy layer, and a fixed magnetization layer takes a form wherein an inner pin layer and an outer pin layer are stacked one upon another with a nonmagnetic intermediated layer sandwiched between them. The inner pin layer is made up of a multilayer structure including a second Heusler alloy layer. The first and second Heusler alloy layers are each formed by a co-sputtering technique using a split target split into at least two sub-targets in such a way as to constitute a Heusler alloy layer composition. When the Heusler alloy layer is formed, therefore, it is possible to bring up a film-deposition rate, improve productivity, and improve the performance of the device.
    Type: Application
    Filed: June 1, 2007
    Publication date: March 6, 2008
    Applicant: TDK CORPORATION
    Inventors: Yoshihiro TSUCHIYA, Tomohito Mizuno, Koji Shimazawa
  • Publication number: 20080019060
    Abstract: The invention provides a magneto-resistive effect device having a CPP (current perpendicular to plane) structure comprising a nonmagnetic spacer layer, and a fixed magnetized layer and a free layer stacked one upon another with said nonmagnetic spacer layer sandwiched between them, with a sense current applied in a stacking direction, wherein said free layer functions such that its magnetization direction changes depending on an external magnetic field, and is made up of a multilayer structure including a Heusler alloy layer, wherein an Fe layer is formed on one of both planes of said Heusler alloy layer in the stacking direction, wherein said one plane is near to at least a nonmagnetic spacer layer side, and said fixed magnetization layer is made up of a multilayer structure including a Heusler alloy layer, wherein Fe layers are formed on both plane sides of said Heusler alloy layer in the stacking direction with said Heusler alloy layer sandwiched between them.
    Type: Application
    Filed: June 13, 2007
    Publication date: January 24, 2008
    Applicant: TDK CORPORATION
    Inventors: Tomohito MIZUNO, Yoshihiro Tsuchiya, Koji Shimazawa
  • Publication number: 20070297104
    Abstract: A method for manufacturing a magnetic field detecting element having a free layer whose magnetization direction is variable depending on an external magnetic field and a pinned layer whose magnetization direction is fixed with respect to the external magnetic field, said free layer and said pinned layer being stacked with an electrically conductive, nonmagnetic spacer layer sandwiched therebetween, wherein sense current is configured to flow in a direction that is perpendicular to film planes of the magnetic field detecting element is provided. The method has the steps of: forming a spacer adjoining layer that is adjacent to said spacer layer, Heusler alloy layer, and a metal layer successively in this order; and forming either at least a part of said pinned layer or said free layer by heating said spacer adjoining layer, said Heusler alloy layer, and said metal layer. The spacer adjoining layer has a layer that is chiefly made of cobalt and iron.
    Type: Application
    Filed: June 22, 2007
    Publication date: December 27, 2007
    Inventors: Tomohito MIZUNO, Yoshihiro TSUCHIYA, Koji SHIMAZAWA, Kei HIRATA, Keita KAWAMORI
  • Publication number: 20070291422
    Abstract: A method for manufacturing a magnetic field detecting element has the steps of: forming stacked layers by sequentially depositing a pinned layer, a spacer layer, a spacer adjoining layer which is adjacent to the spacer layer, a metal layer, and a Heusler alloy layer in this order, such that the layers adjoin each other; and heat treating the stacked layers in order to form the free layer out of the spacer adjoining layer, the metal layer, and the Heusler alloy layer. The spacer adjoining layer is mainly formed of cobalt and iron, and has a body centered cubic structure, and the metal layer is formed of an element selected from the group consisting of silver, gold, copper, palladium, or platinum, or is formed of an alloy thereof.
    Type: Application
    Filed: February 21, 2007
    Publication date: December 20, 2007
    Applicant: TDK Corporation
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Kei Hirata, Keita Kawamori, Koji Shimazawa
  • Patent number: 7310210
    Abstract: A magnetoresistive sensor comprises a pinned layer having a magnetization direction fixed with respect to an external magnetic field, a free layer, having a magnetization direction variable in accordance with the external magnetic field, and a spacer layer mainly containing copper, sandwiched between the pinned layer and the free layer. A sense current flows through the pinned layer, the spacer layer, and the free layer substantially in a direction in which the layers are stacked.
    Type: Grant
    Filed: January 27, 2005
    Date of Patent: December 18, 2007
    Assignee: TDK Corporation
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20070274010
    Abstract: An MR element incorporates a nonmagnetic conductive layer, and a pinned layer and a free layer that are disposed to sandwich the nonmagnetic conductive layer. Each of the pinned layer and the free layer includes a Heusler alloy layer. The Heusler alloy layer contains a Heusler alloy in which atoms of a magnetic metallic element are placed at body-centered positions of unit cells, and an additive element that is a nonmagnetic metallic element that does not constitute the Heusler alloy. At least one of the pinned layer and the free layer includes a region in which the concentration of the additive element increases as the distance from the nonmagnetic conductive layer decreases, the region being adjacent to the nonmagnetic conductive layer.
    Type: Application
    Filed: March 20, 2007
    Publication date: November 29, 2007
    Applicant: TDK CORPORATION
    Inventors: Kei Hirata, Yoshihiro Tsuchiya, Tomohito Mizuno, Koji Shimazawa
  • Publication number: 20070242396
    Abstract: In an MR element, each of a pinned layer and a free layer includes a Heusler alloy layer. The Heusler alloy layer has two surfaces that are quadrilateral in shape and face toward opposite directions. The Heusler alloy layer includes one crystal grain that touches four sides of one of the two surfaces. In a method of manufacturing the MR element, a layered film to be the MR element is formed and patterned, and then heat treatment is performed on the layered film patterned, so that crystal grains included in a film to be the Heusler alloy layer in the layered film grow and one crystal grain that touches four sides of one of the surfaces of the film to be the Heusler alloy layer is thereby formed.
    Type: Application
    Filed: March 8, 2007
    Publication date: October 18, 2007
    Applicant: TDK CORPORATION
    Inventors: Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno, Daisuke Miyauchi, Shinji Hara, Takahiko Machita
  • Publication number: 20070230070
    Abstract: A pinned layer of an MR element includes an underlying magnetic layer made of a magnetic alloy layer having a body-centered cubic structure, and a Heusler alloy layer formed on the underlying magnetic layer. A free layer of the MR element includes an underlying magnetic layer made of a magnetic alloy layer having a body-centered cubic structure, and a Heusler alloy layer formed on the underlying magnetic layer. Each of these two Heusler alloy layers is made of a CoMnSi alloy having an Mn content higher than 25 atomic percent and lower than or equal to 40 atomic percent, and contains a principal component having a B2 structure in which Co atoms are placed at body-centered positions of unit cells and Mn atoms or Si atoms are randomly placed at vertexes of the unit cells.
    Type: Application
    Filed: February 22, 2007
    Publication date: October 4, 2007
    Applicant: TDK CORPORATION
    Inventors: Tomohito Mizuno, Yoshihiro Tsuchiya
  • Publication number: 20070217087
    Abstract: A magnetic thin film has a layer which is formed of an alloy having a ordered crystal structure whose composition formula is represented by XYZ or X2YZ (where X is one or more than one of the elements selected from the group consisting of Co, Ir, Rh, Pt, and Cu, Y is one or more than one of the elements selected from the group consisting of V, Cr, Mn, and Fe, and Z is one or more than one of the elements selected the group consisting of Al, Si, Ge, As, Sb, Bi, In, Ti, and Pb). The alloy contains at least one additive element which is not included in the composition formula of the alloy and which has a Debye temperature that is equal to or less than 300K.
    Type: Application
    Filed: March 16, 2007
    Publication date: September 20, 2007
    Applicant: TDK Corporation
    Inventors: Kei Hirata, Keita Kawamori, Tomohito Mizuno, Yoshihiro Tsuchiya, Koji Shimazawa
  • Publication number: 20070183098
    Abstract: An MR element has a pinned layer, a spacer layer, and a free layer successively stacked in the order named. The free layer includes a Heusler alloy layer in at least a region thereof adjacent to the spacer layer. An oxide is distributed as sea-islands in the interface between the Heusler alloy layer and the spacer layer. The Heusler alloy layer virtually has a stoichiometric composition. The oxide has an RA in the range from 0.10 ??m2 to 0.36 ??m2.
    Type: Application
    Filed: February 5, 2007
    Publication date: August 9, 2007
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Daisuke Miyauchi, Koji Shimazawa
  • Publication number: 20070121255
    Abstract: A magneto-resistance effect element according to the present invention comprises a pinned layer whose magnetization direction is fixed; a free layer whose magnetization direction varies in accordance with an external magnetic field; and a nonmagnetic spacer layer that is arranged between said pinned layer and said free layer. At least either said pinned layer or said free layer includes a Heusler alloy layer that is disposed adjacent to said spacer layer, and compounds are arranged in a dotted pattern at an interface between said spacer layer and at least said spacer layer and said pinned layer or said spacer layer and said free layer, said compounds including material that is included in said Heusler alloy layer.
    Type: Application
    Filed: September 13, 2006
    Publication date: May 31, 2007
    Applicant: TDK Corporation
    Inventors: Yoshihiro Tsuchiya, Tomohito Mizuno, Koji Shimazawa, Daisuke Miyauchi
  • Publication number: 20070097561
    Abstract: A magneto-resistive element has a pinned layer, a free layer, and a spacer layer which is sandwiched between the pinned layer and the free layer. The spacer layer is made of copper. The magneto-resistive element is configured such that sense current is applied in a direction that is perpendicular to layer surfaces. The free layer has: a nonmagnetic layer that includes copper as a main component; and ternary alloy layers each including cobalt (Co), iron (Fe), and nickel (Ni), the ternary alloy layers being disposed on both sides of the nonmagnetic layer. The ternary alloy layer includes nickel and iron at a composition ratio in which a ratio x of an atomic percentage of nickel to a total atomic percentage of nickel and iron is 27%?x?45%.
    Type: Application
    Filed: October 27, 2006
    Publication date: May 3, 2007
    Applicant: TDK Corporation
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20070086120
    Abstract: A magneto-resistive element has: a first stacked film assembly having a pinned layer, a spacer layer, and a free layer; a first electrode layer which is arranged such that the first layer is in contact with the first electrode layer on the other side of the first layer, the first electrode layer being made of a ferromagnetic material; and a second electrode layer which is arranged on a side that is opposite to the first electrode layer with regard to the first stacked film assembly. The first and second electrode layers are adapted to apply a sense current to the first stacked film assembly and the first layer in a direction that is perpendicular to layer surfaces. The first layer is made of gold, silver, copper, ruthenium, rhodium, iridium, chromium or platinum, or an alloy thereof.
    Type: Application
    Filed: October 17, 2006
    Publication date: April 19, 2007
    Applicant: TDK Corporation
    Inventors: Koji Shimazawa, Daisuke Miyauchi, Tomohito Mizuno, Yoshihiro Tsuchiya
  • Publication number: 20070058301
    Abstract: A magneto-resistance element according to the present invention has a pinned layer whose magnetization direction is fixed; a free layer whose magnetization direction varies in accordance with an external magnetic field; and a nonmagnetic spacer layer that is arranged between the pinned layer and the free layer, at least the pinned layer or the free layer includes a layer having Heusler alloy represented by composition formula X2YZ (where X is a precious metal element, Y is a transition metal of Mn, V, or Ti group, Z is an element from group III to group V), and a part of composition X is replaced with Co, and an atomic composition ratio of Co in composition X is from 0.5 to 0.85.
    Type: Application
    Filed: September 13, 2006
    Publication date: March 15, 2007
    Applicant: TDK Corporation
    Inventors: Koji Shimazawa, Yoshihiro Tsuchiya, Tomohito Mizuno
  • Publication number: 20070019341
    Abstract: An MR device includes a magnetization pinned film having a nonmagnetic intermediate layer positioned on the opposite side of a magnetization free layer while sandwiching a nonmagnetic spacer layer and made of RuCu. In the case of passing read current in the stacking direction via lower and upper electrodes, decrease in a resistance change amount caused by a second magnetization pinned layer can be suppressed. Further, a first magnetization pinned layer and the second magnetization pined layer which are thicker can be antiferromagnetically coupled to each other in magnetic fields in a wider range. Thus, both increase in the resistance change amount and magnetic field stability can be achieved. Therefore, while maintaining stable operations by reducing the influence of external noise, the invention can address higher recording density by the increase in the resistance change amount as a whole.
    Type: Application
    Filed: July 21, 2006
    Publication date: January 25, 2007
    Applicant: TDK Corporation
    Inventors: Tomohito Mizuno, Daisuke Miyauchi
  • Publication number: 20060240289
    Abstract: A free layer of an MR element incorporates a first layer, a second layer, a third layer, a fourth layer, a fifth layer and a sixth layer that are stacked in this order on a nonmagnetic conductive layer. The absolute value of magnetostriction constant of the free layer is 1×10?6 or smaller. The coercivity of the free layer is 20×79.6 A/m or smaller. The first layer is made of an alloy containing ‘a’ atomic percent cobalt and (100?a) atomic percent iron wherein ‘a’ falls within a range of 20 to 50 inclusive. The second layer is made of an alloy containing ‘b’ atomic percent cobalt and (100?b) atomic percent iron wherein ‘b’ falls within a range of 70 to 90 inclusive. In addition, oxidation treatment is given to a surface of the second layer farther from the first layer.
    Type: Application
    Filed: March 29, 2006
    Publication date: October 26, 2006
    Applicant: TDK Corporation
    Inventors: Tomohito Mizuno, Daisuke Miyauchi
  • Publication number: 20060203397
    Abstract: A magneto-resistive effect element includes a free layer having a magnetization direction which varies with respect to an external magnetic field; a pinned layer which includes a stacked structure comprising an outer pinned layer which has a magnetization direction that is fixed with respect to the external magnetic field, a non-magnetic intermediate layer which is made of ruthenium with a thickness of about 0.4 nm, and an inner pinned layer with a thickness of 3 nm or more, wherein the inner pinned layer has a magnetization direction which is fixed with respect to the external magnetic field due to anti-ferromagnetic coupling with the outer pinned layer via the non-magnetic intermediate layer; and a spacer layer sandwiched between the free layer and the inner pinned layer. Sense current flows through the pinned layer, the spacer layer, and the free layer substantially in a stacked direction.
    Type: Application
    Filed: September 6, 2005
    Publication date: September 14, 2006
    Applicant: TDK Corporation
    Inventors: Tomohito Mizuno, Daisuke Miyauchi, Masashi Sano
  • Publication number: 20050254179
    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: Application
    Filed: December 3, 2004
    Publication date: November 17, 2005
    Applicant: TDK CORPORATION
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20050213262
    Abstract: Provided are a magnetoresistive device capable of obtaining a larger amount of resistance change and responding to a higher recording density and a thin film magnetic head comprising the magnetoresistive device. A first magnetization fixed film and a second magnetization fixed film have magnetization directions antiparallel to each other, and the second magnetization fixed film farther from a magnetization free layer is made of, for example, a material including at least one selected from the group consisting of tantalum (Ta), chromium (Cr) and vanadium (V), and has a bulk scattering coefficient of 0.25 or less. Thereby, a bulk scattering effect by the second magnetization fixed film which has a function of canceling out the amount of resistance change between the magnetization free layer and the first magnetization fixed film can be prevented, and a magnetoresistive ratio ?R/R can be improved, and recorded magnetic information with a higher recording density can be read out.
    Type: Application
    Filed: March 11, 2005
    Publication date: September 29, 2005
    Applicant: TDK CORPORATION
    Inventors: Daisuke Miyauchi, Tomohito Mizuno
  • Publication number: 20050174692
    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: Application
    Filed: February 4, 2005
    Publication date: August 11, 2005
    Applicant: TDK Corporation
    Inventors: Daisuke Miyauchi, Tomohito Mizuno