Patents by Inventor Reiko Arai

Reiko Arai 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: 8802247
    Abstract: A medium having high medium S/N and excellent corrosion resistance is achieved. In one embodiment, an adhesion layer, a soft magnetic layer, an intermediate layer, a magnetic recording layer, and a protective layer are deposited, in order, on a substrate. The soft magnetic underlayer consists at least of two soft magnetic layers, the first soft magnetic layer formed on the recording layer side being composed of an amorphous alloy containing 85 at. % or less of Co, and the second soft magnetic layer formed on the substrate side being composed of an alloy containing more than 85 at. % of Co.
    Type: Grant
    Filed: October 17, 2006
    Date of Patent: August 12, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Hiroyuki Matsumoto, Mitsuhiro Shoda, Reiko Arai, Yuzuru Hosoe, Katsumi Mabuchi
  • Patent number: 8705208
    Abstract: According to one embodiment, a PMRM includes a substrate, a soft magnetic underlayer above the substrate, an underlayer above the soft magnetic underlayer, an oxide-containing magnetic layer above the underlayer, and a ferromagnetic layer above the magnetic layer having no oxides. The underlayer controls orientation and segregation of the magnetic layer. The oxide-containing magnetic layer comprises at least two or more magnetic layers, a Cr concentration of the magnetic layer adjacent to the ferromagnetic metal layer is between about 23 at. % and about 32 at. %, and a difference between the Cr concentration of the magnetic layer adjacent to the ferromagnetic metal layer and a magnetic layer having a lowest Cr concentration among the at least three magnetic layers is less than about 25 at. %, the magnetic layer with a lowest Cr concentration has a granular structure, and a nucleation field is greater than about 159.2 kA/m.
    Type: Grant
    Filed: June 30, 2010
    Date of Patent: April 22, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Hiroyuki Nakagawa, Reiko Arai, Ichiro Tamai, Kiwamu Tanahashi
  • Patent number: 8507115
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer having an amorphous structure or a microcrystalline structure, a first seed layer comprised of a magnetic material having an fcc crystal structure including a CoFe alloy formed on a substrate side, and a second seed layer formed on the first seed layer, the second seed layer comprised of a nonmagnetic material having an fcc crystal structure including a NiW alloy. The medium also includes an intermediate layer comprised of Ru or an alloy thereof, a magnetic recording layer, and a protective layer, wherein the layers are sequentially stacked on a substrate in the foregoing order and the protective layer is closer to the substrate than the soft magnetic underlayer. Other embodiments of magnetic recording media, and methods of fabrication, are also described.
    Type: Grant
    Filed: September 14, 2009
    Date of Patent: August 13, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: Reiko Arai, Niroyuki Nakagawa
  • Patent number: 8390956
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes at least one soft magnetic underlayer above a substrate, a seed layer above the at least one soft magnetic underlayer, an intermediate layer above the seed layer, a magnetic recording layer above the intermediate layer, and an overcoat layer above the magnetic recording layer, wherein the seed layer includes a second seed layer above a first seed layer. In another embodiment, the seed layer is a multilayered structure of at least two cycles of a unit of layered film which includes a first seed layer and a second seed layer. The first seed layer includes a non-magnetic alloy having a Face-Centered-Cubic (FCC) structure, and the second seed layer includes a soft magnetic alloy having a FCC structure. Other structures are also disclosed, according to more embodiments.
    Type: Grant
    Filed: June 3, 2010
    Date of Patent: March 5, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: Shun Tonooka, Reiko Arai, Hiroyuki Nakagawa, Kiwamu Tanahashi
  • Patent number: 8071228
    Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium which does not cause medium noise to increase due to soft magnetic underlayers, is capable of easily controlling the thickness of a nonmagnetic layer disposed between soft magnetic underlayers, and capable of improving the corrosion resistance of the soft magnetic underlayers. According to one embodiment, in a perpendicular magnetic recording medium, an adhesion layer is formed on a substrate, a soft magnetic underlayer is formed on the adhesion layer, a seed layer and an intermediate layer are formed above the soft magnetic underlayer, and a perpendicular layer is formed on the intermediate layer.
    Type: Grant
    Filed: November 9, 2007
    Date of Patent: December 6, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Hiroyuki Suzuki, Masayoshi Shimizu
  • Publication number: 20110151144
    Abstract: Embodiments of the invention provide a perpendicular magnetic recording medium improved for fly ability, high in read signal quality, and capable of suppressing magnetic decay of recorded magnetization to be caused by stray fields. In one embodiment, a perpendicular recording layer is formed over a substrate with a soft magnetic underlayer therebetween, then an amorphous or nano-crystalline layer is formed between the substrate and the soft magnetic underlayer. The soft magnetic underlayer includes first and second amorphous soft magnetic layers, as well as a nonmagnetic layer formed between those first and second amorphous soft magnetic layers. The first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of the substrate respectively and coupled with each other antiferromagnetically.
    Type: Application
    Filed: December 15, 2010
    Publication date: June 23, 2011
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Kiwamu Tanahashi, Yoshinori Honda, Mineaki Kodama
  • Publication number: 20110032638
    Abstract: Embodiments of the invention provide a perpendicular magnetic recording medium improved for fly ability, high in read signal quality, and capable of suppressing magnetic decay of recorded magnetization to be caused by stray fields. In one embodiment, a perpendicular recording layer is formed over a substrate with a soft magnetic underlayer therebetween, then an amorphous or nano-crystalline layer is formed between the substrate and the soft magnetic underlayer. The soft magnetic underlayer includes first and second amorphous soft magnetic layers, as well as a nonmagnetic layer formed between those first and second amorphous soft magnetic layers. The first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of the substrate respectively and coupled with each other antiferromagnetically.
    Type: Application
    Filed: October 19, 2010
    Publication date: February 10, 2011
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Kiwamu Tanahashi, Yoshinori Honda, Mineaki Kodama
  • Patent number: 7875371
    Abstract: Embodiments of the invention provide a perpendicular magnetic recording medium improved for fly ability, high in read signal quality, and capable of suppressing magnetic decay of recorded magnetization to be caused by stray fields. In one embodiment, a perpendicular recording layer is formed over a substrate with a soft magnetic underlayer therebetween, then an amorphous or nano-crystalline layer is formed between the substrate and the soft magnetic underlayer. The soft magnetic underlayer includes first and second amorphous soft magnetic layers, as well as a nonmagnetic layer formed between those first and second amorphous soft magnetic layers. The first and second amorphous soft magnetic layers are given uniaxial anisotropy in the radial direction of the substrate respectively and coupled with each other antiferromagnetically.
    Type: Grant
    Filed: April 15, 2005
    Date of Patent: January 25, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Kiwamu Tanahashi, Yoshinori Honda, Mineaki Kodama
  • Patent number: 7875373
    Abstract: Embodiments in accordance with the present invention help to obtain a perpendicular magnetic recording medium having a granular structure, excellent recording/reproducing properties, and excellent durability. According to one embodiment, a recording layer includes a layer which has crystal grains mainly composed of cobalt and crystal grain boundaries mainly composed of the oxide; the oxygen content of the recoding layer is changed in the film thickness direction; the oxygen content in the area in the vicinity of the interface between the recording layer and the intermediate layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer; and the oxygen content in the area in the vicinity of the interface between the recording layer and the protective layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer.
    Type: Grant
    Filed: November 13, 2007
    Date of Patent: January 25, 2011
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Yoshiyuki Hirayama, Ichiro Tamai, Reiko Arai
  • Publication number: 20110002064
    Abstract: According to one embodiment, a PMRM includes a substrate, a soft magnetic underlayer above the substrate, an underlayer above the soft magnetic underlayer, an oxide-containing magnetic layer above the underlayer, and a ferromagnetic layer above the magnetic layer having no oxides. The underlayer controls orientation and segregation of the magnetic layer. The oxide-containing magnetic layer comprises at least two or more magnetic layers, a Cr concentration of the magnetic layer adjacent to the ferromagnetic metal layer is between about 23 at. % and about 32 at. %, and a difference between the Cr concentration of the magnetic layer adjacent to the ferromagnetic metal layer and a magnetic layer having a lowest Cr concentration among the at least three magnetic layers is less than about 25 at. %, the magnetic layer with a lowest Cr concentration has a granular structure, and a nucleation field is greater than about 159.2 kA/m.
    Type: Application
    Filed: June 30, 2010
    Publication date: January 6, 2011
    Inventors: Hiroyuki Nakagawa, Reiko Arai, Ichiro Tamai, Kiwamu Tanahashi
  • Publication number: 20100309580
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes at least one soft magnetic underlayer above a substrate, a seed layer above the at least one soft magnetic underlayer, an intermediate layer above the seed layer, a magnetic recording layer above the intermediate layer, and an overcoat layer above the magnetic recording layer, wherein the seed layer includes a second seed layer above a first seed layer. In another embodiment, the seed layer is a multilayered structure of at least two cycles of a unit of layered film which includes a first seed layer and a second seed layer. The first seed layer includes a non-magnetic alloy having a Face-Centered-Cubic (FCC) structure, and the second seed layer includes a soft magnetic alloy having a FCC structure. Other structures are also disclosed, according to more embodiments.
    Type: Application
    Filed: June 3, 2010
    Publication date: December 9, 2010
    Inventors: Shun Tonooka, Reiko Arai, Hiroyuki Nakagawa, Kiwamui Tanahashi
  • Publication number: 20100110588
    Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer having an amorphous structure or a microcrystalline structure, a first seed layer comprised of a magnetic material having an fcc crystal structure including a CoFe alloy formed on a substrate side, and a second seed layer formed on the first seed layer, the second seed layer comprised of a nonmagnetic material having an fcc crystal structure including a NiW alloy. The medium also includes an intermediate layer comprised of Ru or an alloy thereof, a magnetic recording layer, and a protective layer, wherein the layers are sequentially stacked on a substrate in the foregoing order and the protective layer is closer to the substrate than the soft magnetic underlayer. Other embodiments of magnetic recording media, and methods of fabrication, are also described.
    Type: Application
    Filed: September 14, 2009
    Publication date: May 6, 2010
    Inventors: Reiko Arai, Niroyuki Nakagawa
  • Patent number: 7691500
    Abstract: Embodiments of the present invention help to provide an excellent perpendicular recording medium of high medium signal-to-noise (S/N) and with suppressed blurring in writing. According to one embodiment, a perpendicular recording layer is provided by way of a negative magnetic strain soft-magnetic underlayer above a substrate applied with texturing in the circumferential direction. The soft-magnetic underlayer has a first soft magnetic layer, a second soft magnetic layer and a nonmagnetic magnetic layer formed between the first soft magnetic layer and the second soft magnetic layer in which the first soft magnetic layer and the second soft magnetic layer are antiferromagnetically coupled to each other and the easy magnetization axis is directed in the radial direction.
    Type: Grant
    Filed: November 30, 2007
    Date of Patent: April 6, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Masayoshi Shimizu, Reiko Arai
  • Patent number: 7666530
    Abstract: Embodiments of the invention relate to easily achieving a perpendicular magnetic recording medium with high reliability and a magnetic recording apparatus with high recording density by improving the magnetic properties and surface smoothness of the soft magnetic underlayer and, moreover, enhancing adhesion with the substrate.
    Type: Grant
    Filed: October 6, 2005
    Date of Patent: February 23, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Yoshinori Honda, Hiroyuki Matsumoto
  • Patent number: 7641989
    Abstract: Embodiments of the invention provide a medium which provides high media S/N and good corrosion resistance. According to one embodiment, in a perpendicular magnetic recording medium at least comprising a soft-magnetic underlayer, a seed layer, an intermediate layer, a magnetic recording layer and an overcoat layer which are stacked over a substrate in order, the magnetic recording layer has a granular structure which consists of many columnar grains of CoCrPt alloy and a grain boundary layer containing an oxide, the seed layer is made of TaNi alloy or TaTi alloy and the intermediate layer is made of Ru or Ru alloy which contains about 80 at. % Ru or more.
    Type: Grant
    Filed: December 5, 2005
    Date of Patent: January 5, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Ikuko Takekuma, Reiko Arai, Yoko Ogawa, Yoshiyuki Hirayama, Yuzuru Hosoe, Tomio Iwasaki
  • Patent number: 7534507
    Abstract: Embodiments of the invention are directed to a medium which provides high media S/N and good corrosion resistance. According to one embodiment, in a perpendicular magnetic recording medium at least comprising a soft-magnetic underlayer, a seed layer, an intermediate layer, a magnetic recording layer and an overcoat layer which are stacked over a substrate in order, the magnetic recording layer has a granular structure which includes many columnar grains of CoCrPt alloy and a grain boundary layer containing an oxide, the seed layer is made of TaNi alloy or TaTi alloy and the intermediate layer is made of Ru or Ru alloy which contains 80 at. % Ru or more.
    Type: Grant
    Filed: October 3, 2005
    Date of Patent: May 19, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Yoshiyuki Hirayama, Yuzuru Hosoe, Tomio Iwasaki, Yoko Ogawa, Ikuko Takekuma
  • Publication number: 20080130170
    Abstract: Embodiments of the present invention help to provide an excellent perpendicular recording medium of high medium signal-to-noise (S/N) and with suppressed blurring in writing. According to one embodiment, a perpendicular recording layer is provided by way of a negative magnetic strain soft-magnetic underlayer above a substrate applied with texturing in the circumferential direction. The soft-magnetic underlayer has a first soft magnetic layer, a second soft magnetic layer and a nonmagnetic magnetic layer formed between the first soft magnetic layer and the second soft magnetic layer in which the first soft magnetic layer and the second soft magnetic layer are antiferromagnetically coupled to each other and the easy magnetization axis is directed in the radial direction.
    Type: Application
    Filed: November 30, 2007
    Publication date: June 5, 2008
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Masayoshi Shimizu, Reiko Arai
  • Publication number: 20080124583
    Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium which does not cause medium noise to increase due to soft magnetic underlayers, is capable of easily controlling the thickness of a nonmagnetic layer disposed between soft magnetic underlayers, and capable of improving the corrosion resistance of the soft magnetic underlayers. According to one embodiment, in a perpendicular magnetic recording medium, an adhesion layer is formed on a substrate, a soft magnetic underlayer is formed on the adhesion layer, a seed layer and an intermediate layer are formed above the soft magnetic underlayer, and a perpendicular layer is formed on the intermediate layer.
    Type: Application
    Filed: November 9, 2007
    Publication date: May 29, 2008
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Reiko Arai, Hiroyuki Suzuki, Masayoshi Shimizu
  • Publication number: 20080113221
    Abstract: Embodiments in accordance with the present invention help to obtain a perpendicular magnetic recording medium having a granular structure, excellent recording/reproducing properties, and excellent durability. According to one embodiment, a recording layer includes a layer which has crystal grains mainly composed of cobalt and crystal grain boundaries mainly composed of the oxide; the oxygen content of the recoding layer is changed in the film thickness direction; the oxygen content in the area in the vicinity of the interface between the recording layer and the intermediate layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer; and the oxygen content in the area in the vicinity of the interface between the recording layer and the protective layer is made lower than the oxygen content in the area in the vicinity of the center of the recording layer.
    Type: Application
    Filed: November 13, 2007
    Publication date: May 15, 2008
    Applicant: Hitachi Global Storage Technologies Inc.
    Inventors: Yoshiyuki Hirayama, Ichiro Tamai, Reiko Arai
  • Publication number: 20070285839
    Abstract: Embodiments of the present invention improve the production efficiency of a perpendicular recording medium while ensuring the scratch resistance thereof. In order to realize high production stability in the high speed production of perpendicular recording media, a target is not provided with a texture of a low melting point or the ratio thereof is decreased. Thus according to one embodiment of the present invention, upon forming a layer having an element of a low melting point in the constituent layers of a perpendicular recording medium, a target can be made using an alloy powder previously formed of an intermetallic compound having a melting point higher than 660° C., thereby preventing thermal deformation.
    Type: Application
    Filed: May 16, 2007
    Publication date: December 13, 2007
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hiroyuki Suzuki, Reiko Arai, Hiroyuki Matsumoto, Masayoshi Shimizu