Patents by Inventor Hitoshi Iwasaki

Hitoshi Iwasaki 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: 20070154740
    Abstract: A magnetoresistive device includes a magnetization pinned layer, a magnetization free layer, a nonmagnetic intermediate layer formed between the magnetization pinned layer and the magnetization free layer, and electrodes allowing a sense current to flow in a direction substantially perpendicular to the plane of the stack including the magnetization pinned layer, the nonmagnetic intermediate layer and the magnetization free layer. At least one of the magnetization pinned layer and the magnetization free layer is substantially formed of a binary or ternary alloy represented by the formula FeaCobNic (where a+b+c=100 at %, and a?75 at %, b?75 at %, and c?63 at %), or formed of an alloy having a body-centered cubic crystal structure.
    Type: Application
    Filed: March 13, 2007
    Publication date: July 5, 2007
    Inventors: Hiromi Yuasa, Masatoshi Yoshikawa, Yuzo Kamiguchi, Hitoshi Iwasaki, Masashi Sahashi
  • Patent number: 7223485
    Abstract: A magnetoresistive device includes a magnetization pinned layer, a magnetization free layer, a nonmagnetic intermediate layer formed between the magnetization pinned layer and the magnetization free layer, and electrodes allowing a sense current to flow in a direction substantially perpendicular to the plane of the stack including the magnetization pinned layer, the nonmagnetic intermediate layer and the magnetization free layer. At least one of the magnetization pinned layer and the magnetization free layer is substantially formed of a binary or ternary alloy represented by the formula FeaCobNic (where a+b+c=100 at %, and a?75 at %, b?75 at %, and c?63 at %), or formed of an alloy having a body-centered cubic crystal structure.
    Type: Grant
    Filed: March 7, 2005
    Date of Patent: May 29, 2007
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiromi Yuasa, Masatoshi Yoshikawa, Yuzo Kamiguchi, Hitoshi Iwasaki, Masashi Sahashi
  • Publication number: 20070109147
    Abstract: A high-frequency oscillator includes a high-frequency oscillation element having a magnetization pinned layer whose magnetization direction is pinned substantially in one direction, an oscillation layer formed of a magnetic material which generates a high-frequency oscillation phenomenon when a current is supplied, an intermediate layer provided between the magnetization pinned layer and the oscillation layer, the intermediate layer having an insulation layer and current paths which pass through the insulation layer in a thickness direction, and a pair of electrodes which supply a current perpendicularly to a plane of a stacked film including the magnetization pinned layer, the intermediate layer and the oscillation layer.
    Type: Application
    Filed: September 21, 2006
    Publication date: May 17, 2007
    Inventors: Hideaki Fukuzawa, Hiromi Yuasa, Hitoshi Iwasaki
  • Patent number: 7218484
    Abstract: A magnetoresistance effect element comprises: a magnetoresistance effect film, a pair of electrodes, and a phase separation layer. The magnetoresistance effect film includes a first ferromagnetic layer whose direction of magnetization is pinned substantially in one direction, a second ferromagnetic layer whose direction of magnetization changes in response to an external magnetic field, and an intermediate layer provided between the first and second ferromagnetic layers. The pair of electrodes are electrically coupled to the magnetoresistance effect film and configured to supply a sense current perpendicularly to a film plane of the magnetoresistance effect film. The phase separation layer is provided between the pair of electrodes. The phase separation layer has a first phase and a second phase formed by a phase separation in a solid phase from an alloy including a plurality of elements.
    Type: Grant
    Filed: September 11, 2003
    Date of Patent: May 15, 2007
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Susumu Hashimoto, Katsuhiko Koui, Masashi Sahashi, Hitoshi Iwasaki
  • Patent number: 7218483
    Abstract: A spin valve type magnetoresistive effect element for vertical electric conduction includes a magnetoresistive effect film in which a resistance adjustment layer made of a material containing conductive carriers not more than 1022/cm3 is inserted. Thus the resistance value of a portion in change of spin-relied conduction is raised to an adequate value, thereby to increase the resistance variable amount.
    Type: Grant
    Filed: June 21, 2002
    Date of Patent: May 15, 2007
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiromi Yuasa, Masatoshi Yoshikawa, Katsuhiko Koui, Hitoshi Iwasaki, Masashi Sahashi
  • Publication number: 20070092639
    Abstract: There is provided a method for manufacturing a magnetoresistive element having a magnetization pinned layer, a magnetization free layer, and a spacer layer including an insulating layer arranged between the magnetization pinned layer and the magnetization free layer and current paths passing through the insulating layer. The method includes, in producing the spacer layer, depositing a first non-magnetic metal layer forming the current paths, depositing a second metal layer to be converted into the insulating layer on the first non-magnetic metal layer, and performing two stages of oxidation treatments in which a partial pressure of an oxidizing gas in a first oxidation treatment is set to 1/10 or less of a partial pressure of an oxidizing gas in a second oxidation treatment, and the second metal layer being irradiated with an ion beam or a RF plasma of a rare gas in the first oxidation treatment.
    Type: Application
    Filed: October 20, 2006
    Publication date: April 26, 2007
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yoshihiko Fuji, Hideaki Fukuzawa, Hiromi Yuasa, Hitoshi Iwasaki
  • Publication number: 20070081276
    Abstract: A magnetoresistance effect element comprises a magnetoresistance effect film and a pair of electrode. The magnetoresistance effect film having a first magnetic layer whose direction of magnetization is substantially pinned in one direction; a second magnetic layer whose direction of magnetization changes in response to an external magnetic field; a nonmagnetic intermediate layer located between the first and second magnetic layers; and a film provided in the first magnetic layer, in the second magnetic layer, at a interface between the first magnetic layer and the nonmagnetic intermediate layer, and/or at a interface between the second magnetic layer and the nonmagnetic intermediate layer, the film having a thickness not larger than 3 nanometers, and the film has as least one selected from the group consisting of nitride, oxinitride, phosphide, and fluoride.
    Type: Application
    Filed: December 12, 2006
    Publication date: April 12, 2007
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Hiromi Yuasa, Hiromi Fuke, Hitoshi Iwasaki, Masashi Sahashi
  • Patent number: 7196877
    Abstract: A magnetoresistive element includes a magnetoresistive film having a magnetization pinned layer, a magnetization free layer, and a nonmagnetic intermediate layer. A magnetization direction of the magnetization pinned layer is substantially fixed in an external magnetic field, a magnetization direction of the magnetization free layer is configured to change in the external magnetic field, and the nonmagnetic intermediate layer formed between the magnetization pinned layer and the magnetization free layer and has a stacked structure of a first non-metallic intermediate layer/a metal intermediate layer/a second non-metallic intermediate layer. The magnetoresistive element also includes a pair of electrodes coupled to the magnetoresistive film and is configured to provide a current in a direction substantially perpendicular to a surface of the magnetoresistive film.
    Type: Grant
    Filed: December 23, 2003
    Date of Patent: March 27, 2007
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Masatoshi Yoshikawa, Masayuki Takagishi, Tomomi Funayama, Kohichi Tateyama, Hitoshi Iwasaki, Hideaki Fukuzawa
  • Patent number: 7190558
    Abstract: In a CPP element using a metal intermediate layer excellent in shot noise and response to high frequencies unlike a TMR element, its magnetoresistive effect film includes a magnetic layer mainly made of a half-metal exhibiting ferromagnetism, ferrimagnetism or antiferromagnetism, and largely variable in way of conduction in response to spin direction of electrons.
    Type: Grant
    Filed: June 24, 2002
    Date of Patent: March 13, 2007
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hitoshi Iwasaki, Katsuhiko Koui, Masatoshi Yoshikawa, Hiromi Yuasa, Hideaki Fukuzawa, Masashi Sahashi
  • Publication number: 20070029368
    Abstract: A plurality of anode foils (7) and a plurality of cathode foils (8) respectively having connecting portions (12a, 12b) are alternately arranged with insulating separators (9) interposed therebetween. The connecting portions (12a, 12b) of the stacked electrode foils (7, 8) are respectively connected and united electrically and mechanically by friction stir welding, thereby forming a capacitor element (5). The capacitor element (5) is housed in a case (2), and the connecting portions (12a, 12b) are respectively connected to a positive electrode external terminal (4) and a negative electrode external terminal (4).
    Type: Application
    Filed: March 19, 2004
    Publication date: February 8, 2007
    Applicant: Nippon Chemi-Con Corporation
    Inventors: Tatsuo Kubouchi, Hitoshi Iwasaki, Makoto Shimizu
  • Patent number: 7145754
    Abstract: A magnetoresistance effect element comprises a magnetoresistance effect film including a magnetically pinned layer whose direction of magnetization is pinned substantially in one direction, a magnetically free layer whose direction of magnetization changes in response to an external magnetic field, and a nonmagnetic intermediate layer located between the pinned layer and the free layer, and a pair of electrodes electrically connected to said magnetoresistance effect film to supply a sense current perpendicularly to a film plane of said magnetoresistance effect film. The intermediate layer has a first layer including a first region whose resistance is relatively high and second regions whose resistance is relatively low. The sense current preferentially flows through the second regions when the current passes the first layer.
    Type: Grant
    Filed: February 22, 2005
    Date of Patent: December 5, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Katsuhiko Koui, Masatoshi Yoshikawa, Masayuki Takagishi, Masashi Sahashi, Takeo Sakakubo, Hitoshi Iwasaki
  • Publication number: 20060268470
    Abstract: A magnetoresistive element includes at least three metallic magnetic layers, connection layers each provided between the metallic magnetic layers, and electrodes which supply a current perpendicularly to a plane of a stack of the metallic magnetic layers and the connection layers. A magnetization direction of a lowermost or uppermost metallic magnetic layer of the metallic magnetic layers is pinned, and a magnetization direction of an intermediate metallic magnetic layer is twisted such that magnetization directions of the lowermost and the uppermost metallic magnetic layers are made substantially orthogonal to each other at zero external field.
    Type: Application
    Filed: May 26, 2006
    Publication date: November 30, 2006
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Hiromi Yuasa, Hitoshi Iwasaki
  • Patent number: 7130163
    Abstract: There are provided a magnetoresistance effect element, a magnetic head, a magnetic head assembly and a magnetic recording system, which have high sensitivity and high reliability. The magnetoresistance effect element has two ferromagnetic layers, a non-magnetic layer provided between the ferromagnetic layers, and a layer containing an oxide or nitride as a principal component, wherein the layer containing the oxide or nitride as the principal component contains a magnetic transition metal element which does not bond to oxygen and nitrogen and which is at least one of Co, Fe and Ni.
    Type: Grant
    Filed: October 6, 2004
    Date of Patent: October 31, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Katsuhiko Koi, Hiromi Fuke, Hiroshi Tomita, Hitoshi Iwasaki, Masashi Sahashi
  • Patent number: 7130164
    Abstract: A magnetoresistance effect element comprises a magnetoresistance effect film including a magnetically pinned layer whose direction of magnetization is pinned substantially in one direction, a magnetically free layer whose direction of magnetization changes in response to an external magnetic field, and a nonmagnetic intermediate layer located between the pinned layer and the free layer; and a pair of electrodes electrically connected to said magnetoresistance effect film to supply a sense current perpendicularly to a film plane of said magnetoresistance effect film. The intermediate layer has a first layer including a first region whose resistance is relatively high and second regions whose resistance is relatively low. The sense current preferentially flows through the second regions when the current passes the first layer.
    Type: Grant
    Filed: February 22, 2005
    Date of Patent: October 31, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Katsuhiko Koui, Masatoshi Yoshikawa, Masayuki Takagishi, Masashi Sahashi, Takeo Sakakubo, Hitoshi Iwasaki
  • Patent number: 7116527
    Abstract: A base film of a hard magnetic film containing Co as a structural element has a crystal metal base film such as a Cr film formed on the main surface of a substrate and a reactive base film (mixing layer) formed between the substrate and the crystal metal base film and having a reactive amorphous layer containing a structural element of the substrate and a structural element of the crystal metal base film. A hard magnetic film containing Co as a structural element is formed on the crystal metal base film. With the crystal metal base film such as the Cr film formed on an amorphous layer, a hard magnetic film with a bi-crystal structure can be obtained with high reproducibility. With the hard magnetic film, magnetic characteristics such as coercive force Hc, residual magnetization Mr, saturated magnetization Ms, and square ratio S can be improved without need to use a thick base film.
    Type: Grant
    Filed: September 29, 1997
    Date of Patent: October 3, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Shin-ichi Nakamura, Yuzo Kamiguchi, Hitoshi Iwasaki, Akio Hori, Susumu Hashimoto
  • Publication number: 20060209472
    Abstract: A magnetoresistive device includes a magnetoresistive film and a pair of electrodes for applying a sense current substantially perpendicularly to the magnetoresistive film. The magnetoresistive film includes a magnetization pinned film including a first ferromagnetic layer having a magnetization direction substantially pinned in one direction, a magnetization free film including a second ferromagnetic layer whose magnetization direction changes in accordance with an external magnetic field applied thereto, an intermediate layer formed between the magnetization pinned film and the magnetization free film and having an insulating film and a metal conduction portion extending in the film thickness direction of the insulating film, and a layer containing an electrovalent or covalent compound formed near the metal conduction portion.
    Type: Application
    Filed: March 8, 2006
    Publication date: September 21, 2006
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Katsuhiko Koui, Kohichi Tateyama, Tomomi Funayama, Koichi Kubo, Hitoshi Iwasaki, Hideaki Fukuzawa
  • Publication number: 20060198063
    Abstract: A base film of a hard magnetic film containing Co as a structural element has a crystal metal base film such as a Cr film formed on the main surface of a substrate and a reactive base film (mixing layer) formed between the substrate and the crystal metal base film and having a reactive amorphous layer containing a structural element of the substrate and a structural element of the crystal metal base film. A hard magnetic film containing Co as a structural element is formed on the crystal metal base film. With the crystal metal base film such as the Cr film formed on an amorphous layer, a hard magnetic film with a bi-crystal structure can be obtained with high reproducibility. With the hard magnetic film, magnetic characteristics such as coercive force Hc, residual magnetization Mr, saturated magnetization Ms, and square ratio S can be improved without need to use a thick base film.
    Type: Application
    Filed: May 4, 2006
    Publication date: September 7, 2006
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Hideaki Fukuzawa, Shin-ichi Nakamura, Yuzo Kamiguchi, Hitoshi Iwasaki, Akio Hori, Susumu Hashimoto
  • Publication number: 20060181814
    Abstract: A magnetoresistance effect element comprises a magnetoresistance effect film including a magnetically pinned layer whose direction of magnetization is pinned substantially in one direction, a magnetically free layer whose direction of magnetization changes in response to an external magnetic field, and a nonmagnetic intermediate layer located between the pinned layer and the free layer; and a pair of electrodes electrically connected to said magnetoresistance effect film to supply a sense current perpendicularly to a film plane of said magnetoresistance effect film, The intermediate layer has a first layer including a first region whose resistance is relatively high and second regions whose resistance is relatively low. The sense current preferentially flows through the second regions when the current passes the first layer.
    Type: Application
    Filed: April 7, 2006
    Publication date: August 17, 2006
    Inventors: Katsuhiko Koui, Masatoshi Yoshikawa, Masayuki Takagishi, Masashi Sahashi, Takeo Sakakubo, Hitoshi Iwasaki
  • Publication number: 20060164764
    Abstract: There is provided a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers to be controlled, and a magnetic head and magnetic recording and/or reproducing system using the same. In a magnetoresistance effect element wherein a sense current is caused to flow in a direction perpendicular to the plane of the film, a resistance regulating layer is provided in at least one of a pinned layer, a free layer and an non-magnetic intermediate layer. The resistance regulating layer contains, as a principal component, an oxide, a nitride, a fluoride, a carbide or a boride. The resistance regulating layer may be a continuous film or may have pin holes. Thus, it is possible to provide a practical magnetoresistance effect element which has an appropriate value of resistance, which can be sensitized and which has a small number of magnetic layers, while effectively utilizing the scattering effect depending on spin.
    Type: Application
    Filed: March 27, 2006
    Publication date: July 27, 2006
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Yuuzo Kamiguchi, Hiromi Yuasa, Tomohiko Nagata, Hiroaki Yoda, Katsuhiko Koui, Masatoshi Yoshikawa, Hitoshi Iwasaki, Masashi Sahashi, Masayuki Takagishi
  • Patent number: 7071522
    Abstract: In a spin valve type element, an interface insertion layer (32, 34) of a material exhibiting large spin-dependent interface scattering is inserted in a location of a magnetically pinned layer (16) or a magnetically free layer (20) closer to a nonmagnetic intermediate layer (18). A nonmagnetic back layer (36) may be additionally inserted as an interface not in contact with the nonmagnetic intermediate layer to increase the output by making use of spin-dependent interface scattering along the interface between the pinned layer and the nonmagnetic back layer or between the free layer and the nonmagnetic back layer.
    Type: Grant
    Filed: July 9, 2004
    Date of Patent: July 4, 2006
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hiromi Yuasa, Yuzo Kamiguchi, Masatoshi Yoshikawa, Katsuhiko Koui, Hitoshi Iwasaki, Tomohiko Nagata, Takeo Sakakubo, Masashi Sahashi