Patents by Inventor David Djayaprawira

David Djayaprawira 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).

  • Patent number: 8174800
    Abstract: A magnetoresistive element includes an antiferromagnetic layer formed from a layer containing manganese, a layered magnetization fixed layer which includes a first magnetization fixed layer located over a side of the antiferromagnetic layer and formed from a layer containing a ferromagnetic material and a platinum group metal, a second magnetization fixed layer formed from a layer containing a ferromagnetic material, and a first nonmagnetic intermediate layer located between the first magnetization fixed layer and the second magnetization fixed layer, a magnetic free layer formed from a layer containing a ferromagnetic material, and a second nonmagnetic intermediate layer located between the layered magnetization fixed layer and the magnetic free layer.
    Type: Grant
    Filed: May 2, 2008
    Date of Patent: May 8, 2012
    Assignee: Canon Anelva Corporation
    Inventors: Koji Tsunekawa, David Djayaprawira
  • Publication number: 20080055793
    Abstract: A magnetoresistance effect device including a multilayer structure having a pair of ferromagnetic layers and a barrier layer positioned between them, wherein at least one ferromagnetic layer has at least the part contacting the barrier layer made amorphous and the barrier layer is an MgO layer having a highly oriented texture structure.
    Type: Application
    Filed: October 23, 2007
    Publication date: March 6, 2008
    Applicants: ANELVA CORPORATION, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
    Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai, Hiroki Maehara, Shinji Yamagata, Naoki Watanabe, Shinji Yuasa
  • Publication number: 20070169699
    Abstract: This application discloses a method and apparatus for manufacturing a magnetoresistive multilayer film having a structure where an antiferromagnetic layer, a pinned-magnetization layer, a nonmagnetic spacer layer and a free-magnetization layer are laminated on a substrate in this order. A film for the antiferromagnetic layer is deposited by sputtering as oxygen gas is added to a gas for the sputtering. A film for an extra layer interposed between the substrate and the antiferromagnetic layer is deposited by sputtering as oxygen gas is added to a gas for the sputtering. The film for the antiferromagnetic layer is deposited by sputtering as a gas mixture of argon and another gas of larger atomic number than argon is used.
    Type: Application
    Filed: March 20, 2007
    Publication date: July 26, 2007
    Applicant: CANON ANELVA CORPORATION
    Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
  • Publication number: 20070070553
    Abstract: A magnetoresistance effect device has a fixed ferromagnetism layer, a free ferromagnetism layer, and a barrier layer sandwiched by these ferromagnetic layers. It is constituted so that CoFeB whose amount of addition of boron B (b: atomic %) is 21%?b?23% may be used for the free ferromagnetism layer. In the magnetic resistance effect element, a magnetostrictive constant does not change steeply near the magnetostrictive constant zero. A MR ratio is maintained to be high.
    Type: Application
    Filed: September 27, 2006
    Publication date: March 29, 2007
    Applicant: Canon ANELVA Corporation
    Inventors: Koji Tsunekawa, David Djayaprawira
  • Publication number: 20060056115
    Abstract: A magnetoresistance effect device including a multilayer structure having a pair of ferromagnetic layers and a barrier layer positioned between them, wherein at least one ferromagnetic layer has at least the part contacting the barrier layer made amorphous and the barrier layer is an MgO layer having a highly oriented texture structure.
    Type: Application
    Filed: September 7, 2005
    Publication date: March 16, 2006
    Applicants: ANELVA Corporation, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY
    Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai, Hiroki Maehara, Shinji Yamagata, Naoki Watanabe, Shinji Yuasa
  • Publication number: 20050227122
    Abstract: A vertical magnetic recording medium exhibiting excellent noise characteristics in which magnetic interaction is reduced in a magnetic layer. The vertical magnetic recording medium (10) includes a nonmagnetic substrate (1), an underlying layer (2) formed directly or indirectly on the nonmagnetic substrate (1), and a magnetic layer (4) for recording magnetic information formed on the underlying layer (2), characterized in that the underlying layer (2) is composed of an alloy principally including two kinds of element, difference of standard free energy ?G° for producing an oxide or a nitride of the both elements at room temperature is set not lower than 70 kJ/mol[O2 or N2], and crystal grains constituting the underlying layer (2) principally includes one of two elements having a higher ?G°, and the grain boundary of the underlying layer (2) principally includes an oxide or a nitride of an element having a lower ?G°.
    Type: Application
    Filed: March 20, 2003
    Publication date: October 13, 2005
    Inventors: Migaku Takahashi, David Djayaprawira, Hirold Domon
  • Publication number: 20050214584
    Abstract: A method for producing a magnetic recording medium having a flat surface and a strong exchange bias field, and excellent in thermal stability. The method for producing a magnetic recording medium related to the present invention comprising a nonmagnetic substrate 1, a metal underlayer 2, and a ferromagnetic metal layer 3 formed successively in multilayer. The method comprises a step of forming the ferromagnetic layer 3 where ferromagnetic films 3a, 3b and one or more nonmagnetic metal spacer layer 4 are alternately formed in a multilayer and a step of allowing at least the interface of the nonmagnetic metal spacer layers 4 to physically adsorb oxygen and/or nitrogen.
    Type: Application
    Filed: March 20, 2003
    Publication date: September 29, 2005
    Inventors: Migaku Takahashi, David Djayaprawira, Hiroki Domon, Satoru Yoshimura
  • Publication number: 20050158585
    Abstract: A vertical magnetic recording medium has a low-noise characteristic compared to media of a permalloy or sendust crystalline material, including a high-flatness soft magnetic backing layer, and enabling recording/reproduction of information at high recording density, a magnetic recorder provided with the vertical magnetic recording medium, a vertical magnetic recording medium manufacturing method and apparatus. The vertical magnetic recording medium has a multilayer structure on a substrate, in which a soft magnetic backing layer, a vertical recording layer of a ferromagnetic body, and a protective layer are formed. The soft magnetic backing layer is formed of an FeSiAlN film of a soft magnetic material. The atom % of each element of Fe, Si, Al, and N of the FeSiAlN film can be changed by changing the flow rate of N2 gas in a mixture gas of N2 gas and Ar gas introduced into the chamber.
    Type: Application
    Filed: March 20, 2003
    Publication date: July 21, 2005
    Inventors: Migaku Takahashi, Shin Saito, David Djayaprawira
  • Publication number: 20050083612
    Abstract: This application discloses a method and apparatus for manufacturing a magnetoresistive multilayer film having a structure where an antiferromagnetic layer, a pinned-magnetization layer, a nonmagnetic spacer layer and a free-magnetization layer are laminated on a substrate in this order. A film for the antiferromagnetic layer is deposited by sputtering as oxygen gas is added to a gas for the sputtering. A film for an extra layer interposed between the substrate and the antiferromagnetic layer is deposited by sputtering as oxygen gas is added to a gas for the sputtering. The film for the antiferromagnetic layer is deposited by sputtering as a gas mixture of argon and another gas of larger atomic number than argon is used.
    Type: Application
    Filed: October 18, 2004
    Publication date: April 21, 2005
    Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
  • Patent number: 6878459
    Abstract: A magnetic recording medium was a high normalized coercive force and superior thermal stability. The magnetic recording medium comprises a non-magnetic base material, and a ferromagnetic metal layer of cobalt based alloy formed on top of this base material with a metal underlayer disposed therebetween, and displays a coercive force Hc of at least 2000 (Oe) and an anisotropic magnetic field Hkgrain of at least 10,000 (Oe). Furthermore, magnetic recording media in which the aforementioned metal underlayer and/or the ferromagnetic metal layer are fabricated in a film fabrication chamber with an ultimate vacuum at the 10?9 Torr level are preferred. A magnetic recording medium according to the present invention can be ideally applied to hard disks, floppy disks, and magnetic tapes and the like.
    Type: Grant
    Filed: December 27, 2001
    Date of Patent: April 12, 2005
    Assignees: Anelva Corporation, Fuji Electric Co., Ltd., Showa Denko K.K.
    Inventors: Migaku Takahashi, David Djayaprawira, Kazuya Komiyama, Satoru Yoshimura
  • Publication number: 20050068695
    Abstract: This application discloses a magnetoresistive multilayer film having the structure where an antiferromagnetic layer, a pinned-magnetization layer, a non-magnetic spacer layer and a free-magnetization layer are laminated in this order. An opposite-side layer is provided on the side of the antiferromagnetic layer opposite to the pinned-magnetization layer. The opposite-side layer has components of nickel and chromium. Atomic numeral ratio of chromium in the opposite-side layer is preferrably not less than 41% and not more than 70%, more preferrally not less than 43%.
    Type: Application
    Filed: September 24, 2004
    Publication date: March 31, 2005
    Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
  • Patent number: 6841259
    Abstract: A magnetic thin film with a saturation magnetic flux density of 2 T or more and a coercive force of 2 Oe or less for a magnetic pole material of a recording head. The magnetic thin film consists of an iron carbide film that includes a martensite (??) phase as the principal phase and at least carbon and iron as constituent elements. The iron carbide film preferably consists of a single ?? phase. The iron carbide film has a body-centered tetragonal structure and a c-axis constitutes an axis of hard magnetization and, a c-plane constitutes a plane of easy magnetization. The axis of hard magnetization constitutes a direction which is generally perpendicular to the film surface, and the plane of easy magnetization constitutes a direction which is generally parallel to the film surface.
    Type: Grant
    Filed: November 20, 2000
    Date of Patent: January 11, 2005
    Inventors: Migaku Takahashi, David Djayaprawira, Hiroki Shoji
  • Publication number: 20040265570
    Abstract: A vertical magnetic recording medium enabling information recording/reproduction with high-recording density and having a soft magnetic backing layer that enables low-noise recording, can be thin, and is excellent in corrosion resistance and its manufacturing method are disclosed. The vertical magnetic recording medium (10) having a soft magnetic backing layer (12) and a vertical recording layer (12) as to serve as a main recording layer and having an easy-magnetization axis mainly oriented vertically to the film surface is characterized in that the soft magnetic backing layer (12) characterized by being made of a soft magnetic material having a composition of FeTaN.
    Type: Application
    Filed: March 22, 2004
    Publication date: December 30, 2004
    Inventors: Migaku Takahashi, Shin Saito, David Djayaprawira
  • Patent number: 6709775
    Abstract: A magnetic recording medium capable of suppressing the effects of thermal agitation and simultaneously reducing the average grain diameter and the standard deviation of magnetic crystal grains constituting a ferromagnetic metal film, without changing the film thickness of a metal under-layer or the film thickness of a ferromagnetic metal layer forming a recording layer, as well as a production method thereof, and a magnetic recording device. The magnetic recording medium includes a ferromagnetic metal layer of a cobalt based alloy formed on a base material with a metal underlayer having chromium as a major constituent disposed there between, wherein a seed layer having at least tungsten is provided between the base material and the metal under-layer, and the seed layer is an islands type film.
    Type: Grant
    Filed: November 28, 2001
    Date of Patent: March 23, 2004
    Inventors: Migaku Takahashi, Satoru Yoshimura, David Djayaprawira, Hiroki Shoji
  • Publication number: 20020146594
    Abstract: A magnetic recording medium with a favorable S/N ratio, for which a high coercive force is possible, as well as a method of producing such a medium, and a magnetic recording device which utilizes such a medium. The magnetic recording medium includes a non-magnetic substrate, and a nucleation layer, a metal underlayer, and a ferromagnetic metal layer for recording magnetic information formed either directly or indirectly on top of the non-magnetic substrate, wherein the nucleation layer includes either an alloy incorporating at least Nb, or an alloy incorporating at least one element selected from the group consisting of V, Mo and W. Moreover, the nucleation layer should preferably also include at least one element selected from the group consisting of Ni, Co, Fe and Cu. The magnetic recording medium according to the present invention can be ideally applied to hard disks, floppy disks, and magnetic tapes and the like.
    Type: Application
    Filed: January 23, 2002
    Publication date: October 10, 2002
    Applicant: MIGAKU TAKAHASHI
    Inventors: Migaku Takahashi, David Djayaprawira, Masaki Mikami
  • Publication number: 20020127434
    Abstract: The present invention provides a magnetic recording medium with a high normalized coercive force and superior thermal stability, as well as a method of producing such a magnetic recording medium and a magnetic recording device incorporating such a magnetic recording medium. A magnetic recording medium according to the present invention comprises a non-magnetic base material, and a ferromagnetic metal layer of cobalt based alloy formed on top of this base material with a metal underlayer disposed therebetween, and displays a coercive force Hc of at least 2000 (Oe) and an anisotropic magnetic field Hkgrain of at least 10,000 (Oe). Furthermore, magnetic recording media in which the aforementioned metal underlayer and/or the ferromagnetic metal layer are fabricated in a film fabrication chamber with an ultimate vacuum at the 10−9 Torr level are preferred.
    Type: Application
    Filed: December 27, 2001
    Publication date: September 12, 2002
    Inventors: Migaku Takahashi, David Djayaprawira, Kazuya Komiyama, Satoru Yoshimura