Patents by Inventor Naoto Nagaosa

Naoto Nagaosa 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: 20190214513
    Abstract: A photoelectric conversion device includes a photoelectric conversion element formed of a polar material and including no p-n junction, and first and second electrodes provided on the photoelectric conversion element and arranged at an interval. Space-inversion symmetry of a structure of the photoelectric conversion element is broken. The first and second electrodes are each formed of a metal material that generates no substantial potential barrier preventing majority carriers for the photoelectric conversion element from moving from the electrode to the photoelectric conversion element.
    Type: Application
    Filed: December 27, 2018
    Publication date: July 11, 2019
    Applicant: RIKEN
    Inventors: Masao NAKAMURA, Masashi KAWASAKI, Yoshinori TOKURA, Naoto NAGAOSA, Takahiro MORIMOTO, Yoshio KANEKO
  • Patent number: 10141068
    Abstract: A magnetic element capable of generating and erasing a skyrmion, including a magnet shaped as a thin layer and including a structure surrounded by a nonmagnetic material; a current path provided surrounding an end region including an end portion of the magnet, on one surface of the magnet; and a skyrmion sensor that detects the generation and erasing of the skyrmion. With Wm being width of the magnet and hm being height of the magnet, a size of the magnet, with the skyrmion of a diameter ? being generated, is such that 2?>Wm>?/2 and 2?>hm>?/2. With W being width of the end region in a direction parallel to the end portion of the magnet and h being height of the end region in a direction perpendicular to the end portion of the magnet, the end region is such that ??W>?/4 and 2?>h>?/2.
    Type: Grant
    Filed: March 1, 2017
    Date of Patent: November 27, 2018
    Assignee: RIKEN
    Inventors: Naoto Nagaosa, Wataru Koshibae, Junichi Iwasaki, Masashi Kawasaki, Yoshinori Tokura, Yoshio Kaneko
  • Publication number: 20180175285
    Abstract: An electronic device is provided, including: a first drive electrode; a second drive electrode that is spaced apart from the first drive electrode; and a topological insulator that contacts both of the first drive electrode and the second drive electrode and has magnetism, wherein the topological insulator includes a first region having a first coercivity and a second region having a second coercivity that is different from the first coercivity. A fabrication method of a topological insulator is also provided, including: preparing a topological insulator having magnetism and a first coercivity; and forming a second region having a second coercivity that is different from the first coercivity by irradiating a partial region of the topological insulator with ions.
    Type: Application
    Filed: February 12, 2018
    Publication date: June 21, 2018
    Inventors: Ryutaro YOSHIMI, Masataka MOGI, Naoto NAGAOSA, Masashi KAWASAKI, Yoshinori TOKURA, Wataru KOSHIBAE
  • Patent number: 10003010
    Abstract: Provided is a magnetic element capable of generating one skyrmion and erasing the one skyrmion. The magnetic element includes a magnet shaped like a substantially rectangular flat plate, an upstream electrode connected to the magnet in a width Wm direction of the magnet and made of a non-magnetic metal, a downstream electrode connected to the magnet in the width Wm direction to oppose the upstream electrode and made of a non-magnetic metal, and a skyrmion sensor configured to detect the skyrmion. Here, a width Wm of the substantially rectangular magnet is such that 3·?>Wm??, where ? denotes a diameter of the skyrmion, a length Hm of the substantially rectangular magnet is such that 2·?>Hm??, and the magnet has a notch structure at the edge between the upstream electrode and the downstream electrode.
    Type: Grant
    Filed: March 3, 2017
    Date of Patent: June 19, 2018
    Assignee: RIKEN
    Inventors: Naoto Nagaosa, Wataru Koshibae, Junichi Iwasaki, Masashi Kawasaki, Yoshinori Tokura, Yoshio Kaneko
  • Patent number: 9859017
    Abstract: To provide a magnetic element capable of performing skyrmion transfer, a skyrmion memory to which this magnetic element is applied, and a shift register, for example, a magnetic element capable of performing skyrmion transfer is provided, the magnetic element providing a transverse transfer arrangement in which the skyrmion is transferred substantially perpendicular to a current between an upstream electrode and a downstream electrode, and including a plurality of stable positions in which the skyrmion exists more stably than in other regions of a magnet, and a skyrmion sensor that detects a position of the skyrmion.
    Type: Grant
    Filed: March 5, 2017
    Date of Patent: January 2, 2018
    Assignee: RIKEN
    Inventors: Naoto Nagaosa, Wataru Koshibae, Junichi Iwasaki, Masashi Kawasaki, Yoshinori Tokura, Yoshio Kaneko
  • Patent number: 9824712
    Abstract: A magnetic storage media which has an endurance (durability) characteristics close to an infinite number of writing times of data and a data retention (holding) characteristics close to permanency, and is ultra-high-speed writable and erasable, and a data storage device and an image storage device which apply this magnetic storage media are provided. A magnetic storage media includes a thin layer magnet and a magnetic field generating unit arranged facing a surface of the magnet, and is capable of creating or eliminating a skyrmion by applying heat energy to another surface of the magnet positioned on the opposite side of the surface of the magnet, and a skyrmion memory includes the magnetic storage media.
    Type: Grant
    Filed: February 3, 2017
    Date of Patent: November 21, 2017
    Assignee: RIKEN
    Inventors: Naoto Nagaosa, Wataru Koshibae, Junichi Iwasaki, Masashi Kawasaki, Yoshinori Tokura, Yoshio Kaneko
  • Patent number: 9748000
    Abstract: Provided is a skyrmion memory circuit capable of circularly transferring a magnetic element skyrmion, comprising one or more current paths in a magnet having a closed-path pattern that are provided surrounding an end region including an end portion of the magnet in a plane of the magnet with the closed-path pattern, and applying current between an outer terminal connected to an outer circumferential portion of the closed-path pattern and an inner circumference electrode connected to an inner circumferential portion of the closed-path pattern, transferring the skyrmion in a direction substantially perpendicular to the direction of the applied current, and circulating the skyrmion in the magnet with the closed-path pattern.
    Type: Grant
    Filed: December 28, 2016
    Date of Patent: August 29, 2017
    Assignee: RIKEN
    Inventors: Naoto Nagaosa, Wataru Koshibae, Junichi Iwasaki, Masashi Kawasaki, Yoshinori Tokura, Yoshio Kaneko
  • Patent number: 9741420
    Abstract: A skyrmion driving method that utilizes electric current to make it possible to perform driving ON-OFF control at high speed and to suppress the influence of an inertial effect so that the driving control can be performed further logically. The skyrmion is driven based on a driving amount proportional to a time-integrated value of an electric current density j(t) (Am?2) at a clock time t for a location R(t) of the skyrmion at the clock time t and on a driving amount that is in accordance with a diffusive motion due to thermal fluctuation and increases as a Gilbert attenuation constant increases.
    Type: Grant
    Filed: August 10, 2016
    Date of Patent: August 22, 2017
    Assignees: RIKEN, University of Cologne
    Inventors: Naoto Nagaosa, Achim Rosch, Christoph Schuette
  • Publication number: 20170206921
    Abstract: A magnetic storage media which has an endurance (durability) characteristics close to an infinite number of writing times of data and a data retention (holding) characteristics close to permanency, and is ultra-high-speed writable and erasable, and a data storage device and an image storage device which apply this magnetic storage media are provided. A magnetic storage media includes a thin layer magnet and a magnetic field generating unit arranged facing a surface of the magnet, and is capable of creating or eliminating a skyrmion by applying heat energy to another surface of the magnet positioned on the opposite side of the surface of the magnet, and a skyrmion memory includes the magnetic storage media.
    Type: Application
    Filed: February 3, 2017
    Publication date: July 20, 2017
    Inventors: Naoto NAGAOSA, Wataru KOSHIBAE, Junichi IWASAKI, Masashi KAWASAKI, Yoshinori TOKURA, Yoshio KANEKO
  • Publication number: 20170178746
    Abstract: To provide a magnetic element capable of performing skyrmion transfer, a skyrmion memory to which this magnetic element is applied, and a shift register, for example, a magnetic element capable of performing skyrmion transfer is provided, the magnetic element providing a transverse transfer arrangement in which the skyrmion is transferred substantially perpendicular to a current between an upstream electrode and a downstream electrode, and including a plurality of stable positions in which the skyrmion exists more stably than in other regions of a magnet, and a skyrmion sensor that detects a position of the skyrmion.
    Type: Application
    Filed: March 5, 2017
    Publication date: June 22, 2017
    Inventors: Naoto NAGAOSA, Wataru KOSHIBAE, Junichi IWASAKI, Masashi KAWASAKI, Yoshinori TOKURA, Yoshio KANEKO
  • Publication number: 20170178748
    Abstract: A magnetic element capable of generating and erasing a skyrmion, including a magnet shaped as a thin layer and including a structure surrounded by a nonmagnetic material; a current path provided surrounding an end region including an end portion of the magnet, on one surface of the magnet; and a skyrmion sensor that detects the generation and erasing of the skyrmion. With Wm being width of the magnet and hm being height of the magnet, a size of the magnet, with the skyrmion of a diameter ? being generated, is such that 2?>Wm>?/2 and 2?>hm>?/2. With W being width of the end region in a direction parallel to the end portion of the magnet and h being height of the end region in a direction perpendicular to the end portion of the magnet, the end region is such that ??W>?/4 and 2?>h>?/2.
    Type: Application
    Filed: March 1, 2017
    Publication date: June 22, 2017
    Inventors: Naoto NAGAOSA, Wataru KOSHIBAE, Junichi IWASAKI, Masashi KAWASAKI, Yoshinori TOKURA, Yoshio KANEKO
  • Publication number: 20170179375
    Abstract: Provided is a magnetic element capable of generating one skyrmion and erasing the one skyrmion. The magnetic element includes a magnet shaped like a substantially rectangular flat plate, an upstream electrode connected to the magnet in a width Wm direction of the magnet and made of a non-magnetic metal, a downstream electrode connected to the magnet in the width Wm direction to oppose the upstream electrode and made of a non-magnetic metal, and a skyrmion sensor configured to detect the skyrmion. Here, a width Wm of the substantially rectangular magnet is such that 3·?>Wm??, where ? denotes a diameter of the skyrmion, a length Hm of the substantially rectangular magnet is such that 2·?>Hm??, and the magnet has a notch structure at the edge between the upstream electrode and the downstream electrode.
    Type: Application
    Filed: March 3, 2017
    Publication date: June 22, 2017
    Inventors: Naoto NAGAOSA, Wataru KOSHIBAE, Junichi IWASAKI, Masashi KAWASAKI, Yoshinori TOKURA, Yoshio KANEKO
  • Publication number: 20170169898
    Abstract: Provided is a skyrmion memory circuit capable of circularly transferring a magnetic element skyrmion, comprising one or more current paths in a magnet having a closed-path pattern that are provided surrounding an end region including an end portion of the magnet in a plane of the magnet with the closed-path pattern, and applying current between an outer terminal connected to an outer circumferential portion of the closed-path pattern and an inner circumference electrode connected to an inner circumferential portion of the closed-path pattern, transferring the skyrmion in a direction substantially perpendicular to the direction of the applied current, and circulating the skyrmion in the magnet with the closed-path pattern.
    Type: Application
    Filed: December 28, 2016
    Publication date: June 15, 2017
    Inventors: Naoto NAGAOSA, Wataru KOSHIBAE, Junichi IWASAKI, Masashi KAWASAKI, Yoshinori TOKURA, Yoshio KANEKO
  • Publication number: 20160351242
    Abstract: A skyrmion driving method that utilizes electric current to make it possible to perform driving ON-OFF control at high speed and to suppress the influence of an inertial effect so that the driving control can be performed further logically. The skyrmion is driven based on a driving amount proportional to a time-integrated value of an electric current density j(t) (Am?2) at a clock time t for a location R(t) of the skyrmion at the clock time t and on a driving amount that is in accordance with a diffusive motion due to thermal fluctuation and increases as a Gilbert attenuation constant increases.
    Type: Application
    Filed: August 10, 2016
    Publication date: December 1, 2016
    Inventors: Naoto NAGAOSA, Achim ROSCH, Christoph SCHUETTE
  • Publication number: 20110253204
    Abstract: A solar cell 1 has a p-n junction structure between a first solid material layer 3 comprising an insulator or a semiconductor and a second solid material layer 5 comprising an insulator or a semiconductor of a type different from the type of the first solid material layer 3, in which structure a Mott insulator or a Mott semiconductor is used as a solid material of at least one of the layers.
    Type: Application
    Filed: April 7, 2011
    Publication date: October 20, 2011
    Inventors: Wataru Koshibae, Masao Nakamura, Masashi Kawasaki, Naoto Nagaosa, Yasujiro Taguchi, Yoshinori Tokura, Nobuo Furukawa
  • Patent number: 7978047
    Abstract: A variable resistance element comprises a variable resistor of strongly-correlated material sandwiched between two metal electrodes, and the electric resistance between the metal electrodes varies when a voltage pulse is applied between the metal electrodes. Such a switching operation as the ratio of electric resistance between low and high resistance states is high can be attained by designing the metal electrodes and variable resistor appropriately based on a definite switching operation principle. Material and composition of the first electrode and variable resistor are set such that metal insulator transition takes place on the interface of the first electrode in any one of two metal electrodes and the variable resistor by applying a voltage pulse. Two-phase coexisting phase of metal and insulator phases can be formed in the vicinity of the interface between the variable resistor and first electrode by the work function difference between the first electrode and variable resistor.
    Type: Grant
    Filed: August 8, 2006
    Date of Patent: July 12, 2011
    Assignees: Sharp Kabushiki Kaisha, National Science and Technology
    Inventors: Yasunari Hosoi, Shigeo Ohnishi, Yasushi Ogimoto, Takashi Oka, Naoto Nagaosa, Yoshinori Tokura
  • Publication number: 20090231083
    Abstract: A variable resistance element comprises a variable resistor of strongly-correlated material sandwiched between two metal electrodes, and the electric resistance between the metal electrodes varies when a voltage pulse is applied between the metal electrodes. Such a switching operation as the ratio of electric resistance between low and high resistance states is high can be attained by designing the metal electrodes and variable resistor appropriately based on a definite switching operation principle. Material and composition of the first electrode and variable resistor are set such that metal insulator transition takes place on the interface of the first electrode in any one of two metal electrodes and the variable resistor by applying a voltage pulse. Two-phase coexisting phase of metal and insulator phases can be formed in the vicinity of the interface between the variable resistor and first electrode by the work function difference between the first electrode and variable resistor.
    Type: Application
    Filed: August 8, 2006
    Publication date: September 17, 2009
    Inventors: Yasunari Hosoi, Shigeo Ohnishi, Yasushi Ogimoto, Takashi Oka, Naoto Nagaosa, Yoshinori Tokura
  • Patent number: 7037807
    Abstract: A device and a method for generating an electric-field-induced spin current are disclosed. A highly spin-polarized electric current is generated using a semiconductor structure and an applied electric field across the semiconductor structure. The semiconductor structure can be a hole-doped semiconductor having finite or zero bandgap or an undoped semiconductor of zero bandgap. In one embodiment, a device for injecting spin-polarized current into a current output terminal includes a semiconductor structure including first and second electrodes, along a first axis, receiving an applied electric field and a third electrode, along a direction perpendicular to the first axis, providing the spin-polarized current. The semiconductor structure includes a semiconductor material whose spin orbit coupling energy is greater than room temperature (300 Kelvin) times the Boltzmann constant. In one embodiment, the semiconductor structure is a hole-doped semiconductor structure, such as a p-type GaAs semiconductor layer.
    Type: Grant
    Filed: December 24, 2003
    Date of Patent: May 2, 2006
    Assignee: The Board of Trustees of the Leland Stanford Junior University
    Inventors: Shuichi Murakami, Naoto Nagaosa, Shoucheng Zhang
  • Patent number: 6985276
    Abstract: A magnetooptic element whose size is essentially that of a lattice, namely several angstroms in size of magnetic material and which at the same time has its exhibiting magnetooptic effect detectable is provided along with a magnetooptic disk, a memory device and a magnetooptical picture or image display with a storage capacity of several terabits per square inch or more, each using such a magnetooptic element. The magnetooptic element utilizes a gigantic effective magnetic filed based on a spin chirality formed by geometrically configuring the spin orientation and crystallographic structure of a certain solid material.
    Type: Grant
    Filed: March 20, 2002
    Date of Patent: January 10, 2006
    Assignees: National Institute of Advanced Industrial Science and Technology, Japan Science and Technology Agency
    Inventors: Yasujiro Taguchi, Yoshio Kaneko, Yoshinori Tokura, Naoto Nagaosa
  • Publication number: 20040245510
    Abstract: A magnetooptic element whose size is essentially that of a lattice, namely several angstroms in size of magnetic material and which at the same time has its exhibiting magnetooptic effect detectable is provided along with a magnetooptic disk, a memory device and a magnetooptical picture or image display with a storage capacity of several terabits per square inch or more, each using such a magnetooptic element. The magnetooptic element utilizes a gigantic effective magnetic filed based on a spin chirality formed by geometrically configuring the spin orientation and crystallographic structure of a certain solid material.
    Type: Application
    Filed: March 19, 2004
    Publication date: December 9, 2004
    Inventors: Yasujiro Taguchi, Yoshio Kaneko, Yoshinori Tokura, Naoto Nagaosa