Patents by Inventor Kazuya Niwa

Kazuya Niwa 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: 20190392860
    Abstract: A heat-assisted magnetic recording medium includes: a substrate; an underlayer; and a magnetic layer including an alloy having an L10 structure, wherein the underlayer includes, from the substrate side, a bcc underlayer including a substance having a bcc structure, a first oxide layer that is in contact with the bcc underlayer, and a second oxide layer that is in contact with the magnetic layer. The bcc underlayer, the first oxide layer, and the second oxide layer are stacked in the recited order. The first oxide layer and the second oxide layer include magnesium oxide, and the second oxide layer further includes one or more compounds selected from the group consisting of vanadium oxide, vanadium nitride, and vanadium carbide.
    Type: Application
    Filed: June 6, 2019
    Publication date: December 26, 2019
    Inventors: Lei ZHANG, Chen XU, Takayuki FUKUSHIMA, Kazuya NIWA, Tetsuya KANBE, Hisato SHIBATA, Takehiro YAMAGUCHI, Tomoo SHIGE
  • Publication number: 20190355387
    Abstract: A magnetic recording medium includes: a substrate; an underlayer; and a magnetic layer including an alloy having a L10 structure and a (001) orientation, wherein the substrate, the underlayer, and the magnetic layer are stacked in the recited order, and wherein the magnetic layer has a granular structure and includes a carbon hydride, a boron hydride, or a boron nitride hydride.
    Type: Application
    Filed: May 9, 2019
    Publication date: November 21, 2019
    Inventors: Takayuki FUKUSHIMA, Kazuya NIWA, Lei ZHANG, Hisato SHIBATA, Takehiro YAMAGUCHI, Chen XU, Tetsuya KANBE, Tomoo SHIGE
  • Patent number: 10360936
    Abstract: The invention provides a magnetic recording medium with an excellent signal-to-noise ratio during reading by reducing the noise produced during writing of data onto the magnetic recording medium, and increasing the signal level. The assisted magnetic recording medium according to one embodiment comprising a substrate, a base layer, and a magnetic layer composed mainly of an alloy with an L10-type crystal structure, the assisted magnetic recording medium having a pinning layer in contact with the magnetic layer, and the pinning layer including Co or an alloy composed mainly of Co.
    Type: Grant
    Filed: January 31, 2018
    Date of Patent: July 23, 2019
    Assignee: SHOWA DENKO K.K.
    Inventors: Kazuya Niwa, Tetsuya Kanbe, Yuji Murakami, Lei Zhang, Hisato Shibata, Takayuki Fukushima, Satoru Nakajima, Takehiro Yamaguchi
  • Publication number: 20190180782
    Abstract: A magnetic recording medium includes a substrate, an underlayer provided on the substrate, and a magnetic layer provided on the underlayer and having a L10 structure and a (001) orientation. The magnetic layer has a granular structure in which an organic compound having a methylene skeleton or a methine skeleton is arranged at grain boundaries of magnetic grains.
    Type: Application
    Filed: October 24, 2018
    Publication date: June 13, 2019
    Inventors: Katsumi MUROFUSHI, Yoshitaka ISHIBASHI, Takayuki FUKUSHIMA, Kazuya NIWA, Lei ZHANG, Yuji MURAKAMI, Hisato SHIBATA, Takehiro YAMAGUCHI, Chen XU, Tetsuya KANBE, Tomoo SHIGE
  • Patent number: 10283154
    Abstract: A magnetic recording medium includes a substrate, a barrier layer, a crystal grain size control layer, and a magnetic layer that are arranged in this order. The barrier layer includes at least one of oxides, nitrides, and carbides, and the crystal grain size control layer is a crystalline layer including Ag and having an average thickness in a range of 0.1 nm to 1 nm. The barrier layer makes contact with the crystal grain size control layer, and the magnetic layer includes an alloy having a L10 crystal structure and a (001) face orientation.
    Type: Grant
    Filed: May 15, 2018
    Date of Patent: May 7, 2019
    Assignees: SHOWA DENKO K.K., TOHOKU UNIVERSITY
    Inventors: Shintaro Hinata, Shin Saito, Takayuki Fukushima, Haruhisa Ohashi, Kazuya Niwa, Lei Zhang, Yuji Murakami, Hisato Shibata, Takehiro Yamaguchi, Tetsuya Kanbe, Tomoo Shige
  • Publication number: 20180358041
    Abstract: A magnetic recording medium includes a substrate, a barrier layer, a crystal grain size control layer, and a magnetic layer that are arranged in this order. The barrier layer includes at least one of oxides, nitrides, and carbides, and the crystal grain size control layer is a crystalline layer including Ag and having an average thickness in a range of 0.1 nm to 1 nm. The barrier layer makes contact with the crystal grain size control layer, and the magnetic layer includes an alloy having a L10 crystal structure and a (001) face orientation.
    Type: Application
    Filed: May 15, 2018
    Publication date: December 13, 2018
    Inventors: Shintaro HINATA, Shin SAITO, Takayuki FUKUSHIMA, Haruhisa OHASHI, Kazuya NIWA, Lei ZHANG, Yuji MURAKAMI, Hisato SHIBATA, Takehiro YAMAGUCHI, Tetsuya KANBE, Tomoo SHIGE
  • Patent number: 10127939
    Abstract: A magnetic recording medium includes a substrate, a first heat sink layer, a barrier layer, a second heat sink layer, and a magnetic layer that are successively stacked. The magnetic layer is made of a material including a first main component that is an alloy having a L10 crystal structure and a content of 50 at % or higher, or content of 50 mol % or higher. The barrier layer is made of a material including a second main component that is one of an oxide, a nitride, and a carbide having a content of 50 at % or higher, or content of 50 mol % or higher.
    Type: Grant
    Filed: January 11, 2018
    Date of Patent: November 13, 2018
    Assignee: SHOWA DENKO K.K.
    Inventors: Kazuya Niwa, Lei Zhang, Yuji Murakami, Hisato Shibata, Takayuki Fukushima, Takehiro Yamaguchi, Tetsuya Kanbe
  • Publication number: 20180261245
    Abstract: The invention provides a magnetic recording medium with an excellent signal-to-noise ratio during reading by reducing the noise produced during writing of data onto the magnetic recording medium, and increasing the signal level. The assisted magnetic recording medium according to one embodiment comprising a substrate, a base layer, and a magnetic layer composed mainly of an alloy with an L10-type crystal structure, the assisted magnetic recording medium having a pinning layer in contact with the magnetic layer, and the pinning layer including Co or an alloy composed mainly of Co.
    Type: Application
    Filed: January 31, 2018
    Publication date: September 13, 2018
    Applicant: SHOWA DENKO K.K.
    Inventors: Kazuya NIWA, Tetsuya KANBE, Yuji MURAKAMI, Lei ZHANG, Hisato SHIBATA, Takayuki FUKUSHIMA, Satoru NAKAJIMA, Takehiro YAMAGUCHI
  • Publication number: 20180240487
    Abstract: A magnetic recording medium includes a substrate, a first heat sink layer, a barrier layer, a second heat sink layer, and a magnetic layer that are successively stacked. The magnetic layer is made of a material including a first main component that is an alloy having a L10 crystal structure and a content of 50 at % or higher, or content of 50 mol % or higher. The barrier layer is made of a material including a second main component that is one of an oxide, a nitride, and a carbide having a content of 50 at % or higher, or content of 50 mol % or higher.
    Type: Application
    Filed: January 11, 2018
    Publication date: August 23, 2018
    Inventors: Kazuya NIWA, Lei ZHANG, Yuji MURAKAMI, Hisato SHIBATA, Takayuki FUKUSHIMA, Takehiro YAMAGUCHI, Tetsuya KANBE
  • Publication number: 20180182423
    Abstract: A magnetic recording medium includes a substrate, multiple underlayers formed on the substrate, and a magnetic layer foisted on the multiple underlayers. A main component of the magnetic layer is an alloy having a L10 structure. At least one of the multiple underlayers is a crystalline underlayer containing W. The W is a main component of the crystalline underlayer. The crystalline underlayer further contains 1 mol % or more to 20 mol % or less of one or more kinds of elements selected from B, Si, and C. A barrier layer including a material having a NaCl structure is formed between the crystalline underlayer and the magnetic layer.
    Type: Application
    Filed: February 23, 2018
    Publication date: June 28, 2018
    Inventors: Lei ZHANG, Tetsuya KANBE, Yuji MURAKAMI, Kazuya NIWA
  • Publication number: 20180182421
    Abstract: A magnetic recording medium includes a substrate, an underlayer, and a magnetic layer including an alloy having a L10 type crystal structure with a (001) orientation, wherein the substrate, the underlayer, and the magnetic layer are stacked in this order, the underlayer includes a first underlayer, the first underlayer is a crystalline layer that includes a material containing W as a main component and a nitride whose content ranges from 1 mol % to 80 mol %, and the nitride includes one or more elements selected from a group consisting of Al, B, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W.
    Type: Application
    Filed: December 14, 2017
    Publication date: June 28, 2018
    Inventors: Takayuki FUKUSHIMA, Kazuya NIWA, Lei ZHANG, Yuji MURAKAMI, Hisato SHIBATA, Takehiro YAMAGUCHI, Tetsuya KANBE
  • Patent number: 10008220
    Abstract: A magnetic recording medium includes a substrate; a lower base layer formed on the substrate; and a (001) oriented L10 magnetic layer formed on the lower base layer and including a first magnetic layer formed on the lower base layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing C, and a second magnetic layer formed on the first magnetic layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing oxide or nitride, the second magnetic layer further containing one or more elements selected from a group consisting of Mg, Ni, Zn, Ge, Pd, Sn, Ag, Re, Au and Pb as an additive.
    Type: Grant
    Filed: May 16, 2017
    Date of Patent: June 26, 2018
    Assignee: SHOWA DENKO K.K.
    Inventors: Takayuki Fukushima, Yuji Murakami, Tetsuya Kanbe, Lei Zhang, Kazuya Niwa, Hisato Shibata
  • Patent number: 9934810
    Abstract: A magnetic recording medium includes a substrate, multiple underlayers formed on the substrate, and a magnetic layer formed on the multiple underlayers. A main component of the magnetic layer is an alloy having a L10 structure. At least one of the multiple underlayers is a crystalline underlayer containing W. The W is a main component of the crystalline underlayer. The crystalline underlayer further contains 1 mol % or more to 20 mol % or less of one or more kinds of elements selected from B, Si, and C. A barrier layer including a material having a NaCl structure is formed between the crystalline underlayer and the magnetic layer.
    Type: Grant
    Filed: March 20, 2014
    Date of Patent: April 3, 2018
    Assignee: SHOWA DENKO K.K.
    Inventors: Lei Zhang, Tetsuya Kanbe, Yuji Murakami, Kazuya Niwa
  • Publication number: 20170365279
    Abstract: A magnetic recording medium includes a substrate; a lower base layer formed on the substrate; and a (001) oriented L10 magnetic layer formed on the lower base layer and including a first magnetic layer formed on the lower base layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing C, and a second magnetic layer formed on the first magnetic layer and having a granular structure of magnetic grains and a grain boundary portion, the grain boundary portion containing oxide or nitride, the second magnetic layer further containing one or more elements selected from a group consisting of Mg, Ni, Zn, Ge, Pd, Sn, Ag, Re, Au and Pb as an additive.
    Type: Application
    Filed: May 16, 2017
    Publication date: December 21, 2017
    Inventors: Takayuki FUKUSHIMA, Yuji MURAKAMI, Tetsuya KANBE, Lei ZHANG, Kazuya NIWA, Hisato SHIBATA
  • Patent number: 9384772
    Abstract: A magnetic recording medium includes a substrate, a magnetic layer including an alloy having a L10 type crystal structure as a main component thereof, and a plurality of underlayers arranged between the substrate and the magnetic layer. The plurality of underlayers include a first underlayer including two or more elements selected from a group consisting of Ta, Nb, Ti, and V, and one or more elements selected from a group consisting of W and Mo, and a second underlayer including MgO.
    Type: Grant
    Filed: July 17, 2014
    Date of Patent: July 5, 2016
    Assignee: SHOWA DENKO K.K.
    Inventors: Lei Zhang, Tetsuya Kanbe, Yuji Murakami, Kazuya Niwa
  • Patent number: 9361924
    Abstract: A thermally-assisted magnetic recording medium or a microwave-assisted magnetic recording medium includes: an orientation control layer (104) that is formed on a substrate (101); an underlayer (10) that is formed on the orientation control layer (104); and a magnetic layer (108) that is formed on the underlayer (10) and contains an alloy having an L10 type crystal structure as a main component, in which the underlayer (10) includes an MgO underlayer (107) that contains MgO and has a (100) orientation and a nitride underlayer (106) that contains at least one nitride selected from the group consisting of TaN, NbN, and HfN and has a (100) orientation.
    Type: Grant
    Filed: May 10, 2013
    Date of Patent: June 7, 2016
    Assignee: SHOWA DENKO K.K.
    Inventors: Kazuya Niwa, Tetsuya Kanbe, Yuji Murakami, Lei Zhang
  • Patent number: 9251834
    Abstract: A magnetic recording medium includes a substrate, a magnetic layer including an alloy having an L10 type crystal structure as a main component thereof, and a plurality of underlayers arranged between the substrate and the magnetic layer. The plurality of underlayers include at least one crystalline underlayer which has a (100) orientation, and includes W as a main component thereof and one or more kinds of elements selected from a group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc.
    Type: Grant
    Filed: October 1, 2014
    Date of Patent: February 2, 2016
    Assignee: SHOWA DENKO K.K.
    Inventors: Lei Zhang, Tetsuya Kanbe, Yuji Murakami, Kazuya Niwa
  • Patent number: 9245567
    Abstract: A magnetic recording medium includes a substrate, a magnetic layer including a FePt alloy having a L10 type structure, and a plurality of underlayers arranged between the substrate and the magnetic layer, wherein at least one of the plurality of underlayers includes TiO2.
    Type: Grant
    Filed: June 16, 2014
    Date of Patent: January 26, 2016
    Assignee: SHOWA DENKO K.K.
    Inventors: Tetsuya Kanbe, Kazuya Niwa, Yuji Murakami, Lei Zhang
  • Patent number: 9230588
    Abstract: A magnetic recording medium includes a substrate, a magnetic layer including an alloy having an L10 type crystal structure as a main component thereof, a plurality of underlayers arranged between the substrate and the magnetic layer, and a barrier layer made of a material having an NaCl structure. The plurality of underlayers include at least one crystalline underlayer including Mo as a main component thereof, and at least one of Si and C in a range of 1 mol % to 20 mol % and an oxide in a range of 1 vol % to 50 vol %. The barrier layer is provided between the magnetic layer and the at least one crystalline underlayer including Mo.
    Type: Grant
    Filed: July 9, 2014
    Date of Patent: January 5, 2016
    Assignee: SHOWA DENKO K.K.
    Inventors: Lei Zhang, Tetsuya Kanbe, Yuji Murakami, Kazuya Niwa
  • Publication number: 20150117166
    Abstract: A magnetic recording medium includes a substrate, a magnetic layer including an alloy having an L10 type crystal structure as a main component thereof, and a plurality of underlayers arranged between the substrate and the magnetic layer. The plurality of underlayers include at least one crystalline underlayer which has a (100) orientation, and includes W as a main component thereof and one or more kinds of elements selected from a group consisting of Fe, Ni, Co, Hf, Zr, Y, Be, Ce, La, and Sc.
    Type: Application
    Filed: October 1, 2014
    Publication date: April 30, 2015
    Inventors: Lei ZHANG, Tetsuya KANBE, Yuji MURAKAMI, Kazuya NIWA