Patents by Inventor Ichiro Tamai
Ichiro Tamai 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: 9406327Abstract: In one embodiment, a magnetic storage device includes at least one microwave assisted magnetic recording (MAMR) head, each MAMR head including a spin torque oscillator (STO), a magnetic recording medium, a drive mechanism for passing the magnetic medium over the at least one MAMR head, and a controller electrically coupled to the at least one MAMR head for controlling operation of the at least one MAMR head, wherein the magnetic recording medium includes a recording layer positioned directly or indirectly above a substrate and an assist layer positioned above the recording layer, wherein the recording layer includes at least Co, Pt, and an oxide or oxygen, wherein the assist layer is positioned closer to the at least one MAMR head and includes at least Co and Pt, and wherein at least a portion of the recording layer has a smaller anisotropic magnetic field than the assist layer.Type: GrantFiled: August 30, 2013Date of Patent: August 2, 2016Assignee: HGST Netherlands B.V.Inventors: Tatsuya Hinoue, Ichiro Tamai, Hiroaki Nemoto
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Publication number: 20160125903Abstract: In one embodiment, a perpendicular magnetic recording medium includes a substrate; a soft magnetic underlayer positioned above the substrate; a seed layer structure positioned above the soft magnetic underlayer, the seed layer structure including a first seed layer and a second seed layer positioned above the first seed layer; an interlayer structure positioned above the seed layer structure, the interlayer structure including a first interlayer, a second interlayer positioned above the first interlayer, and a third interlayer positioned above the second interlayer; and a magnetic recording layer positioned above the interlayer structure, where the second seed layer includes a Ni alloy including at least one oxide, and where the first interlayer includes a Ru alloy.Type: ApplicationFiled: October 31, 2014Publication date: May 5, 2016Applicant: HGST NETHERLANDS B.V.Inventors: Ichiro Tamai, Tatsuya Hinoue, Shun Tonooka, Hiroaki Nemoto
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Publication number: 20150294679Abstract: In one embodiment, a perpendicular magnetic recording medium includes an oxide recording layer including an oxide and a non-oxide recording layer which does not contain an oxide positioned above the oxide recording layer. The oxide recording layer includes a first recording layer, a second recording layer, a third recording layer, and a fourth recording layer. Also, an oxide concentration of the first recording layer is greater than an oxide concentration of the second recording layer, an oxide concentration of the third recording layer is greater than an oxide concentration of the fourth recording layer, and the oxide concentration of the third recording layer is greater than the oxide concentration of the second recording layer.Type: ApplicationFiled: June 2, 2015Publication date: October 15, 2015Inventors: Shun Tonooka, Kiwamu Tanahashi, Hiroyuki Nakagawa, Ichiro Tamai
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Publication number: 20150262603Abstract: A perpendicular magnetic recording medium with an grain isolation layer is disclosed. In one embodiment, a perpendicular magnetic recording medium comprising a substrate, a soft magnetic under layer formed over the substrate, a seed layer comprising an upper layer and a lower layer formed over the soft magnetic underlayer, an intermediate layer formed of Ru or an Ru alloy formed over the seed layer and a recording layer formed over the intermediate layer, forming a grain isolation layer on the upper layer of the seed layer is provided.Type: ApplicationFiled: March 14, 2014Publication date: September 17, 2015Applicant: HGST Netherlands B.V.Inventors: Shun Tonooka, Masayoshi Shimizu, Ichiro Tamai, Hiroyuki Nakagawa
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Patent number: 9058831Abstract: In one embodiment, a perpendicular magnetic recording medium includes an oxide recording layer including an oxide and a non-oxide recording layer which does not contain an oxide positioned above the oxide recording layer. The oxide recording layer includes a region R1 where a grain boundary width in a direction parallel to a plane of formation of R1 increases therealong from a lowermost portion of the oxide recording layer toward a medium surface, a region R3 positioned above R1 wherein a grain boundary width increases therealong toward the medium surface, a region R2 where a grain boundary width of R2 decreases therealong from R1 to R3, with R2 being positioned between R1 and R3, and a region R4 where a grain boundary width of R4 decreases therealong from R3 toward the medium surface, with R4 being positioned above R3 and near an uppermost portion of the oxide recording layer.Type: GrantFiled: December 14, 2011Date of Patent: June 16, 2015Assignee: HGST Netherlands B.V.Inventors: Shun Tonooka, Kiwamu Tanahashi, Hiroyuki Nakagawa, Ichiro Tamai
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Publication number: 20150085401Abstract: An HDD includes a magnetic head, and a magnetic recording medium. The recording medium includes a recording magnetic layer, and a recording assist magnetic layer, the recording assist magnetic layer generates a high-frequency magnetic field by means of a recording field from the magnetic head, and a recording assist action acts on the recording magnetic layer.Type: ApplicationFiled: September 26, 2013Publication date: March 26, 2015Applicant: HGST Netherlands B.V.Inventors: Hiroaki Nemoto, Ichiro Tamai, Tatsuya Hinoue, Yuzuru Hosoe
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Publication number: 20150062745Abstract: In one embodiment, a magnetic storage device includes at least one microwave assisted magnetic recording (MAMR) head, each MAMR head including a spin torque oscillator (STO), a magnetic recording medium, a drive mechanism for passing the magnetic medium over the at least one MAMR head, and a controller electrically coupled to the at least one MAMR head for controlling operation of the at least one MAMR head, wherein the magnetic recording medium includes a recording layer positioned directly or indirectly above a substrate and an assist layer positioned above the recording layer, wherein the recording layer includes at least Co, Pt, and an oxide or oxygen, wherein the assist layer is positioned closer to the at least one MAMR head and includes at least Co and Pt, and wherein at least a portion of the recording layer has a smaller anisotropic magnetic field than the assist layer.Type: ApplicationFiled: August 30, 2013Publication date: March 5, 2015Applicant: HGST Netherlands B.V.Inventors: Tatsuya Hinoue, Ichiro Tamai, Hiroaki Nemoto
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Patent number: 8771849Abstract: Embodiments of the present invention help allow accurate control of the magnetization reversal in a magnetic recording layer in small reversal units, whereby high-density recording can be achieved. According to one embodiment, by forming an intermediate layer having a granular structure similar to that of the magnetic recording layer below the magnetic recording layer, a continuous crystal grain boundary is formed at the interface between the magnetic recording layer and the intermediate layer, thereby preventing incomplete formation of the crystal grain boundary found in the initial growth layer of the magnetic recording layer. The intermediate layer comprises a non-magnetic alloy comprising Co and Cr as its main components and an oxide such as Al, Cr, Hf. Mg, Nb, Si, Ta, Ti and Zr. Further, the average content of the oxygen element in the intermediate layer is in the range from 6 at % to 20 at %.Type: GrantFiled: October 21, 2008Date of Patent: July 8, 2014Assignee: HGST Netherlands B.V.Inventors: Hiroaki Nemoto, Ikuko Takekuma, Ichiro Tamai, Yoshiyuki Hirayama
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Patent number: 8705208Abstract: 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: GrantFiled: June 30, 2010Date of Patent: April 22, 2014Assignee: HGST Netherlands B.V.Inventors: Hiroyuki Nakagawa, Reiko Arai, Ichiro Tamai, Kiwamu Tanahashi
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Patent number: 8703307Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer formed above a substrate, a lower seed layer formed above the soft magnetic underlayer, at least one upper seed layer formed above the lower seed layer, an interlayer formed above the at least one upper seed layer, a perpendicular recording layer formed above the interlayer, and a protective layer formed above the perpendicular recording layer, wherein the at least one upper seed layer comprises Ni or a Ni based alloy including N, and wherein the lower seed layer includes Ni and at least one element selected from a group consisting of: W and Cr. Other embodiments are described herein regarding perpendicular magnetic recording systems and methods of producing perpendicular magnetic media.Type: GrantFiled: October 12, 2010Date of Patent: April 22, 2014Assignee: HGST Netherlands B.V.Inventors: Akemi Hirotsune, Yotsuo Yahisa, Ichiro Tamai
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Patent number: 8592060Abstract: In one embodiment, a perpendicular magnetic recording medium includes a substrate, a soft-magnetic underlayer above the substrate, a seed layer above the soft-magnetic underlayer, a first intermediate layer above the seed layer, a second intermediate layer above the first intermediate layer, a recording layer above the second intermediate layer, and a protective layer above the recording layer. The second intermediate layer includes an Ru alloy having an element selected from a group consisting of: Ti in a range from about 20 at. % to about 50 at. %, Nb in a range from about 20 at. % to about 50 at. %, Al in a range from about 20 at. % to about 40 at. %, Ta in a range from about 30 at. % to about 50 at. %, and Si in a range about 20 at. % to about 40 at. %. Other magnetic media and systems using this media are described according to more embodiments.Type: GrantFiled: December 21, 2010Date of Patent: November 26, 2013Assignee: HGST Netherlands B.V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune, Kiwamu Tanahashi
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Publication number: 20130155542Abstract: In one embodiment, a perpendicular magnetic recording medium includes an oxide recording layer including an oxide and a non-oxide recording layer which does not contain an oxide positioned above the oxide recording layer. The oxide recording layer includes a region R1 where a grain boundary width in a direction parallel to a plane of formation of R1 increases therealong from a lowermost portion of the oxide recording layer toward a medium surface, a region R3 positioned above R1 wherein a grain boundary width increases therealong toward the medium surface, a region R2 where a grain boundary width of R2 decreases therealong from R1 to R3, with R2 being positioned between R1 and R3, and a region R4 where a grain boundary width of R4 decreases therealong from R3 toward the medium surface, with R4 being positioned above R3 and near an uppermost portion of the oxide recording layer.Type: ApplicationFiled: December 14, 2011Publication date: June 20, 2013Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Shun Tonooka, Kiwamu Tanahashi, Hiroyuki Nakagawa, Ichiro Tamai
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Patent number: 8440332Abstract: Embodiments of the present invention provide a perpendicular magnetic recording medium that reduces the noise of granular recording layers, obtains sufficient overwrite characteristic that suppresses an increase in the magnetic cluster size, and allows high-density recording. According to one embodiment, a perpendicular magnetic recording medium comprising substrate having thereon at least soft magnetic layer, nonmagnetic intermediate layer, a perpendicular recording layer and protective layer formed in that order. The perpendicular recording layer consists of three or more layers of first recording layer, a second recording layer, and a third recording layer from the side nearer to the substrate. The first recording layer and the second recording layer have a granular structure comprising a grain boundary of an oxide surrounding ferromagnetic crystal grains containing Co and Pt, and the third recording layer has a non-granular structure mainly comprising Co and not containing an oxide.Type: GrantFiled: April 8, 2009Date of Patent: May 14, 2013Assignee: HGST Netherlands B.V.Inventors: Ichiro Tamai, Kiwamu Tanahashi
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Publication number: 20120307395Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a first granular recording layer characterized by a magnetic anisotropy Ku1, a second granular recording layer above the first granular recording layer characterized by a magnetic anisotropy Ku2, and a third granular recording layer above the second granular recording layer characterized by a magnetic anisotropy Ku3, wherein Ku3<Ku2>Ku1. In another embodiment, a magnetic medium includes a first recording layer with a first CoCrPt alloy in a first ratio X1, a second recording layer above the first recording layer and having a second CoCrPt alloy in a second ratio X2, and a third recording layer above the second recording layer having a third CoCrPt alloy in a third ratio X3 with each ratio defined as a concentration of Pt divided by a concentration of Cr in the respective CoCrPt alloy, wherein X3<X2>X1.Type: ApplicationFiled: May 31, 2011Publication date: December 6, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Shun Tonooka, Kiwamu Tanahashi, Hiroyuki Nakagawa, Ichiro Tamai
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Publication number: 20120154948Abstract: In one embodiment, a perpendicular magnetic recording medium includes a substrate, a soft-magnetic underlayer above the substrate, a seed layer above the soft-magnetic underlayer, a first intermediate layer above the seed layer, a second intermediate layer above the first intermediate layer, a recording layer above the second intermediate layer, and a protective layer above the recording layer. The second intermediate layer includes an Ru alloy having an element selected from a group consisting of: Ti in a range from about 20 at. % to about 50 at. %, Nb in a range from about 20 at. % to about 50 at. %, Al in a range from about 20 at. % to about 40 at. %, Ta in a range from about 30 at. % to about 50 at. %, and Si in a range about 20 at. % to about 40 at. %. Other magnetic media and systems using this media are described according to more embodiments.Type: ApplicationFiled: December 21, 2010Publication date: June 21, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune, Kiwamu Tanahashi
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Publication number: 20120099220Abstract: In one embodiment, a perpendicular magnetic recording medium includes a crystalline seed layer having a pseudo-hcp structure with stacking faults formed above a soft magnetic underlayer, a first interlayer comprising Ru and one of W, Ta, Mo, and Nb formed above the crystalline seed layer, a second interlayer formed above the first interlayer, and a magnetic recording layer formed above the second interlayer. The first interlayer has a W concentration between about 32 at % and 50 at %, Mo in a concentration between about 36 at % and 52 at %, Ta in a concentration between about 20 at % and 30 at %, or Nb in a concentration between about 7 at % and 30 at %. In another embodiment, a system includes a recording medium as described above, a magnetic head for reading from and/or writing to the medium, a head slider for supporting the head, and a control unit coupled to the head.Type: ApplicationFiled: October 21, 2010Publication date: April 26, 2012Applicant: Hitachi Global Storage Technologies Netherlands B. V.Inventors: Ichiro Tamai, Yotsuo Yahisa, Akemi Hirotsune
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Publication number: 20120087034Abstract: According to one embodiment, a perpendicular magnetic recording medium includes a soft magnetic underlayer formed above a substrate, a lower seed layer formed above the soft magnetic underlayer, at least one upper seed layer formed above the lower seed layer, an interlayer formed above the at least one upper seed layer, a perpendicular recording layer formed above the interlayer, and a protective layer formed above the perpendicular recording layer, wherein the at least one upper seed layer comprises Ni or a Ni based alloy including N, and wherein the lower seed layer includes Ni and at least one element selected from a group consisting of: W and Cr. Other embodiments are described herein regarding perpendicular magnetic recording systems and methods of producing perpendicular magnetic media.Type: ApplicationFiled: October 12, 2010Publication date: April 12, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Akemi Hirotsune, Yotsuo Yahisa, Ichiro Tamai
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Publication number: 20120044595Abstract: In one embodiment, a perpendicular magnetic recording medium (PMRM) includes a first interlayer comprising Ru or a Ru alloy, a second interlayer above the first interlayer comprising Ru or a Ru alloy, and a third interlayer formed between the first interlayer and the second interlayer that reduces an average cluster size of the second interlayer. In another embodiment, a PMRM includes a first interlayer comprising Ru or a Ru alloy, a second interlayer above the first interlayer comprising Ru or a Ru alloy, and a third interlayer formed between the first interlayer and the second interlayer that reduces an average cluster size of the second interlayer. The third interlayer has a thickness of between about 1.0 nm and about 3.0 nm and has a structure selected from a group consisting of: BCC, B2, C11b, L21, and D03. Other PMRMs and methods of fabrication are presented as well.Type: ApplicationFiled: August 23, 2010Publication date: February 23, 2012Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yotsuo Yahisa, Ichiro Tamai, Akemi Hirotsune
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Patent number: 7875373Abstract: 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: GrantFiled: November 13, 2007Date of Patent: January 25, 2011Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yoshiyuki Hirayama, Ichiro Tamai, Reiko Arai
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Publication number: 20110002064Abstract: 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: ApplicationFiled: June 30, 2010Publication date: January 6, 2011Inventors: Hiroyuki Nakagawa, Reiko Arai, Ichiro Tamai, Kiwamu Tanahashi