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).
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Patent number: 8174800Abstract: 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: GrantFiled: May 2, 2008Date of Patent: May 8, 2012Assignee: Canon Anelva CorporationInventors: Koji Tsunekawa, David Djayaprawira
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Publication number: 20080055793Abstract: 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: ApplicationFiled: October 23, 2007Publication date: March 6, 2008Applicants: ANELVA CORPORATION, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGYInventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai, Hiroki Maehara, Shinji Yamagata, Naoki Watanabe, Shinji Yuasa
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Publication number: 20070169699Abstract: 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: ApplicationFiled: March 20, 2007Publication date: July 26, 2007Applicant: CANON ANELVA CORPORATIONInventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
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Publication number: 20070070553Abstract: 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: ApplicationFiled: September 27, 2006Publication date: March 29, 2007Applicant: Canon ANELVA CorporationInventors: Koji Tsunekawa, David Djayaprawira
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Publication number: 20060056115Abstract: 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: ApplicationFiled: September 7, 2005Publication date: March 16, 2006Applicants: ANELVA Corporation, NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGYInventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai, Hiroki Maehara, Shinji Yamagata, Naoki Watanabe, Shinji Yuasa
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Publication number: 20050227122Abstract: 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: ApplicationFiled: March 20, 2003Publication date: October 13, 2005Inventors: Migaku Takahashi, David Djayaprawira, Hirold Domon
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Publication number: 20050214584Abstract: 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: ApplicationFiled: March 20, 2003Publication date: September 29, 2005Inventors: Migaku Takahashi, David Djayaprawira, Hiroki Domon, Satoru Yoshimura
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Publication number: 20050158585Abstract: 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: ApplicationFiled: March 20, 2003Publication date: July 21, 2005Inventors: Migaku Takahashi, Shin Saito, David Djayaprawira
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Publication number: 20050083612Abstract: 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: ApplicationFiled: October 18, 2004Publication date: April 21, 2005Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
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Patent number: 6878459Abstract: 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: GrantFiled: December 27, 2001Date of Patent: April 12, 2005Assignees: Anelva Corporation, Fuji Electric Co., Ltd., Showa Denko K.K.Inventors: Migaku Takahashi, David Djayaprawira, Kazuya Komiyama, Satoru Yoshimura
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Publication number: 20050068695Abstract: 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: ApplicationFiled: September 24, 2004Publication date: March 31, 2005Inventors: David Djayaprawira, Koji Tsunekawa, Motonobu Nagai
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Patent number: 6841259Abstract: 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: GrantFiled: November 20, 2000Date of Patent: January 11, 2005Inventors: Migaku Takahashi, David Djayaprawira, Hiroki Shoji
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Publication number: 20040265570Abstract: 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: ApplicationFiled: March 22, 2004Publication date: December 30, 2004Inventors: Migaku Takahashi, Shin Saito, David Djayaprawira
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Patent number: 6709775Abstract: 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: GrantFiled: November 28, 2001Date of Patent: March 23, 2004Inventors: Migaku Takahashi, Satoru Yoshimura, David Djayaprawira, Hiroki Shoji
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Publication number: 20020146594Abstract: 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: ApplicationFiled: January 23, 2002Publication date: October 10, 2002Applicant: MIGAKU TAKAHASHIInventors: Migaku Takahashi, David Djayaprawira, Masaki Mikami
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Publication number: 20020127434Abstract: 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: ApplicationFiled: December 27, 2001Publication date: September 12, 2002Inventors: Migaku Takahashi, David Djayaprawira, Kazuya Komiyama, Satoru Yoshimura