Patents by Inventor Tadakatsu Ohkubo

Tadakatsu Ohkubo 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: 20160314825
    Abstract: Provided is a structure having a perpendicular magnetization film which is an (Mn1-x,Gax)4N1-y (0<x?0.5, 0<y<1) thin film having a nitrogen-deficient composition which is formed by controlling and introducing nitrogen N into an MnGa alloy or a thin film containing at least one of Ge, Zn, Sb, Ni, Ag, Sn, Pt, and Rh, instead of Ga. The perpendicular magnetization film exhibits a Curie temperature sufficiently higher than room temperature, has saturation magnetization smaller than that of existing materials, and is capable of being fabricated as a very flat film.
    Type: Application
    Filed: April 21, 2016
    Publication date: October 27, 2016
    Inventors: Hiroaki SUKEGAWA, Hwachol LEE, Kazuhiro HONO, Seiji MITANI, Tadakatsu OHKUBO, Jun LIU, Shinya KASAI, Kwangseok KIM
  • Patent number: 8872291
    Abstract: A ferromagnetic tunnel junction structure comprising a first ferromagnetic layer, a second ferromagnetic layer, and a tunnel barrier layer that is interposed between the first ferromagnetic layer and the second ferromagnetic layer, wherein the tunnel barrier layer includes a crystalline non-magnetic material having constituent elements that are similar to those of an crystalline oxide that has spinel structure as a stable phase structure; the non-magnetic material has a cubic structure having a symmetry of space group Fm-3m or F-43m in which atomic arrangement in the spinel structure is disordered; and an effective lattice constant of the cubic structure is substantially half of the lattice constant of the oxide of the spinel structure.
    Type: Grant
    Filed: September 26, 2012
    Date of Patent: October 28, 2014
    Assignee: National Institute For Materials Science
    Inventors: Hiroaki Sukegawa, Seiji Mitani, Tomohiko Niizeki, Tadakatsu Ohkubo, Kouichiro Inomata, Kazuhiro Hono, Masafumi Shirai, Yoshio Miura, Kazutaka Abe, Shingo Muramoto
  • Publication number: 20130068992
    Abstract: An R-T-B based permanent magnet powder, which has been made by an HDDR process and which has an average crystal grain size of 0.1 ?m to 1 ?m and a crystal grain aspect ratio (ratio of the major axis size to the minor axis size) of 2 or less, is provided (Step (A)). R is a rare-earth element, of which at least 95 at % is Nd and/or Pr, and T is either Fe alone or Fe partially replaced with Co and/or Ni and is a transition metal element, of which at least 50 at % is Fe. Meanwhile, an R?—Cu based alloy powder, which is made up of R? and Cu, which accounts for 2 at % to 50 at % of the alloy powder, is also provided (Step (B)). R? is a rare-earth element, of which at least 90 at % is Nd and/or Pr but which includes neither Dy nor Tb. The R-T-B based permanent magnet powder and the R?—Cu based alloy powder are mixed together to obtain a mixed powder (Step (C)). And then the mixed powder is subjected to a heat treatment process at a temperature of 500° C. to 900° C.
    Type: Application
    Filed: May 19, 2011
    Publication date: March 21, 2013
    Inventors: Kazuhiro Hono, Tadakatsu Ohkubo, Hossein Sepehri Amin, Noriyuki Nozawa, Takeshi Nishiuchi, Satoshi Hirosawa