Patents by Inventor Yoshiaki Sonobe

Yoshiaki Sonobe 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: 20200058846
    Abstract: Disclosed is a magnetic tunnel junction device whose fixed layer has a simplified structure and in which the number of stacked layers is reduced. The magnetic tunnel junction device comprises a free layer whose magnetization direction is variable, a fixed layer whose magnetization direction is fixed and that is formed as a single layer, and a dielectric layer stacked between the free layer and the fixed layer. One or more of the free layer and the fixed layer are an L11 type magnetic alloy layer, and the dielectric layer has a (111) texture.
    Type: Application
    Filed: August 9, 2019
    Publication date: February 20, 2020
    Inventors: Hiroyoshi Itoh, Yoshiaki Sonobe
  • Patent number: 10566042
    Abstract: Magnetic tunnel junction devices are provided. A magnetic tunnel junction device includes a pinned layer. The magnetic tunnel junction device includes a free layer on the pinned layer. The free layer includes a first layer, a second layer that is on the first layer, and a third layer that is between the first layer and the second layer. A Curie temperature of the third layer is lower than a Curie temperature of the first layer and lower than a Curie temperature of the second layer. Moreover, the magnetic tunnel junction device includes an insulating layer that is between the pinned layer and the free layer. Related magnetoresistive memory devices are also provided.
    Type: Grant
    Filed: October 24, 2018
    Date of Patent: February 18, 2020
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Ken Machida, Yoshiaki Sonobe, Takeshi Kato
  • Publication number: 20190355403
    Abstract: A magnetoresistive memory device includes a memory cell including a magnetic tunnel junction element, a detector to detect a current value writable in units of the memory cell, a current value storage area, and a current controller. The current value storage area stores at least one of a maximum value and a minimum value of the writable current value detected by the detector. The current controller performs at least one control operation of an operation of controlling a write current value of the memory cell based on the maximum value and an operation of controlling a read current value of the memory cell based on the minimum value.
    Type: Application
    Filed: August 2, 2019
    Publication date: November 21, 2019
    Inventors: Masatoshi SONODA, Yoshiaki SONOBE, Takeshi KATO
  • Patent number: 10431279
    Abstract: A magnetoresistive memory device includes a memory cell including a magnetic tunnel junction element, a detector to detect a current value writable in units of the memory cell, a current value storage area, and a current controller. The current value storage area stores at least one of a maximum value and a minimum value of the writable current value detected by the detector. The current controller performs at least one control operation of an operation of controlling a write current value of the memory cell based on the maximum value and an operation of controlling a read current value of the memory cell based on the minimum value.
    Type: Grant
    Filed: December 14, 2017
    Date of Patent: October 1, 2019
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Masatoshi Sonoda, Yoshiaki Sonobe, Takeshi Kato
  • Patent number: 10395809
    Abstract: Embodiments of the inventive concepts provide a flat perpendicular magnetic layer having a low saturation magnetization and a perpendicular magnetization-type tunnel magnetoresistive element using the same. The perpendicular magnetic layer is a nitrogen-poor (Mn1?xGax)Ny layer (0<x?0.5 and 0<y<0.1) formed by providing nitrogen (N) into a MnGa alloy while adjusting a nitrogen amount. The perpendicular magnetic layer can be formed flat.
    Type: Grant
    Filed: May 10, 2017
    Date of Patent: August 27, 2019
    Assignees: Samsung Electronics Co., Ltd., National Institute for Materials Science
    Inventors: Shigeki Takahashi, Yoshiaki Sonobe, Hiroaki Sukegawa, Hwachol Lee, Kazuhiro Hono, Seiji Mitani, Jun Liu
  • Publication number: 20190164587
    Abstract: Magnetic tunnel junction devices are provided. A magnetic tunnel junction device includes a pinned layer. The magnetic tunnel junction device includes a free layer on the pinned layer. The free layer includes a first layer, a second layer that is on the first layer, and a third layer that is between the first layer and the second layer. A Curie temperature of the third layer is lower than a Curie temperature of the first layer and lower than a Curie temperature of the second layer. Moreover, the magnetic tunnel junction device includes an insulating layer that is between the pinned layer and the free layer. Related magnetoresistive memory devices are also provided.
    Type: Application
    Filed: October 24, 2018
    Publication date: May 30, 2019
    Inventors: KEN MACHIDA, YOSHIAKI SONOBE, TAKESHI KATO
  • Patent number: 10170695
    Abstract: A magnetic tunnel junction device includes a Heusler alloy layer that has not only a perpendicular magnetic anisotropy characteristic, but also a half-metallicity characteristic. For example, the magnetic tunnel junction device includes at least one Heusler alloy layer and a barrier layer. The barrier layer is in contact with the Heusler alloy layer and has an insulating property. A compressive strain is exerted on the Heusler alloy layer in a direction parallel to an interface between the Heusler alloy layer and the barrier layer.
    Type: Grant
    Filed: September 30, 2016
    Date of Patent: January 1, 2019
    Assignee: SAMSUNG ELECTRONICS CO., LTD.
    Inventors: Yoshiaki Sonobe, Hiroyoshi Itoh
  • Publication number: 20180226115
    Abstract: A magnetoresistive memory device includes a memory cell including a magnetic tunnel junction element, a detector to detect a current value writable in units of the memory cell, a current value storage area, and a current controller. The current value storage area stores at least one of a maximum value and a minimum value of the writable current value detected by the detector. The current controller performs at least one control operation of an operation of controlling a write current value of the memory cell based on the maximum value and an operation of controlling a read current value of the memory cell based on the minimum value.
    Type: Application
    Filed: December 14, 2017
    Publication date: August 9, 2018
    Inventors: Masatoshi SONODA, Yoshiaki SONOBE, Takeshi KATO
  • Publication number: 20180069173
    Abstract: A free layer has a switchable magnetization direction. A reference layer has a fixed magnetization direction. A barrier layer is provided between the free layer and the reference layer. The free layer includes a perpendicularity-maintaining layer and a high-polarizability magnetic layer. The perpendicularity-maintaining layer, if in contact with the barrier layer, has a first surface roughness. The high-polarizability magnetic layer, if in contact with the barrier layer, has a second surface roughness. If the first surface roughness is smaller than the second surface roughness, the perpendicularity-maintaining layer is in contact with the barrier layer. If the second surface roughness is smaller than the first surface roughness, the high-polarizability magnetic layer is in contact with the barrier layer.
    Type: Application
    Filed: August 18, 2017
    Publication date: March 8, 2018
    Inventors: Yoshiaki SONOBE, Shigeki NAKAGAWA
  • Publication number: 20170330668
    Abstract: Embodiments of the inventive concepts provide a flat perpendicular magnetic layer having a low saturation magnetization and a perpendicular magnetization-type tunnel magnetoresistive element using the same. The perpendicular magnetic layer is a nitrogen-poor (Mn1?xGax)Ny layer (0<x?0.5 and 0<y<0.1) formed by providing nitrogen (N) into a MnGa alloy while adjusting a nitrogen amount. The perpendicular magnetic layer can be formed flat.
    Type: Application
    Filed: May 10, 2017
    Publication date: November 16, 2017
    Inventors: Shigeki TAKAHASHI, Yoshiaki SONOBE, Hiroaki SUKEGAWA, Hwachol LEE, Kazuhiro HONO, Seiji MITANI, Jun LIU
  • Patent number: 9715915
    Abstract: Magneto-resistive devices with lower power consumption and higher stability are provided. The magneto-resistive devices may include a pinned layer, a free layer and an insulating layer between the pinned layer and the free layer. The pinned layer, the free layer and the insulating layer may constitute a magnetic tunnel junction. The free layer may include a first magnetic layer and a second magnetic layer that has a Curie temperature lower than a Curie temperature of the first magnetic layer.
    Type: Grant
    Filed: October 26, 2015
    Date of Patent: July 25, 2017
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Eiji Kita, Yoshiaki Sonobe
  • Publication number: 20170117458
    Abstract: A magnetic tunnel junction device includes a Heusler alloy layer that has not only a perpendicular magnetic anisotropy characteristic, but also a half-metallicity characteristic. For example, the magnetic tunnel junction device includes at least one Heusler alloy layer and a barrier layer. The barrier layer is in contact with the Heusler alloy layer and has an insulating property. A compressive strain is exerted on the Heusler alloy layer in a direction parallel to an interface between the Heusler alloy layer and the barrier layer.
    Type: Application
    Filed: September 30, 2016
    Publication date: April 27, 2017
    Inventors: Yoshiaki SONOBE, Hiroyoshi ITOH
  • Patent number: 9424873
    Abstract: A method of manufacturing a perpendicular magnetic recording medium 100 that includes forming a magnetic recording layer 122 on a disk base 110, then forming a resist layer 130 on the magnetic recording layer, and a patterning step of processing the resist layer so as to vary the thickness of the resist layer partially, thereby forming a predetermined pattern having a recessed part and a projected part. Finally, the method includes implanting ions into a plurality of layers including the magnetic recording layer with the resist layer interposed. At the ion implanting step, (1) one or more of said plurality of layers to be implanted with ions is determined by selectively applying an energy amount to implant ions, and (2) a total amount of ions to be implanted into each of said one or more of said plurality of layers is determined by selectively applying said energy amount for a respective time period for said one or more of said plurality of layers.
    Type: Grant
    Filed: February 19, 2010
    Date of Patent: August 23, 2016
    Assignee: WD Media (Singapore) Pte. Ltd
    Inventors: Masanori Aniya, Yoshiaki Sonobe
  • Patent number: 9349944
    Abstract: A magnetic tunnel junction device includes: a first magnetic layer that has an easy axis vertical to a surface; a non-magnetic layer on the first magnetic layer; and a second magnetic layer that has an easy axis vertical to a surface on the non-magnetic layer, and an interface layer formed of a Heussler alloy between the non-magnetic layer and at least one of the first and second magnetic layers. The at least one of the first and second magnetic layers is formed of MnGa. A lattice constant of the interface layer parallel to a major surface thereof in a bulk state thereof is between a lattice constant of the non-magnetic layer parallel to a major surface thereof in a bulk state thereof and a lattice constant of the at least one of the first and second magnetic layers parallel to a major surface thereof in a bulk state thereof.
    Type: Grant
    Filed: December 22, 2014
    Date of Patent: May 24, 2016
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Shigeki Takahashi, Yoshiaki Sonobe, Koki Takanashi
  • Publication number: 20160125924
    Abstract: Magneto-resistive devices with lower power consumption and higher stability are provided. The magneto-resistive devices may include a pinned layer, a free layer and an insulating layer between the pinned layer and the free layer. The pinned layer, the free layer and the insulating layer may constitute a magnetic tunnel junction. The free layer may include a first magnetic layer and a second magnetic layer that has a Curie temperature lower than a Curie temperature of the first magnetic layer.
    Type: Application
    Filed: October 26, 2015
    Publication date: May 5, 2016
    Inventors: Eiji KITA, Yoshiaki Sonobe
  • Publication number: 20160087194
    Abstract: A magnetic tunnel junction device includes a memory layer having a variable magnetization direction, a fixed layer maintaining a predetermined magnetization direction, and a spacer layer, wherein the magnetic tunnel junction device performs a data writing operation by using a spin torque injection method, wherein at least one of the memory layer and the fixed layer includes a ferromagnetic insulating layer. Furthermore, the spacer layer may include current paths and an insulator.
    Type: Application
    Filed: September 17, 2015
    Publication date: March 24, 2016
    Inventors: Hiroyoshi ITOH, Yasuyuki KAYAMA, Yoshiaki SONOBE
  • Patent number: 9093100
    Abstract: A magnetic recording medium enabling excellent magnetic recording reproduction characteristics to be exhibited with the spacing loss reduced. The magnetic recording medium has a magnetic recording layer of a granular structure having nonmagnetic boundary portions between pillar-shaped magnetic particles on a nonmagnetic substrate, and an exchange coupling layer provided on the magnetic recording layer to add an action of exchange coupling the magnetic particles. Ion irradiation on the entire surface of the exchange coupling layer after layering the exchange coupling layer on the magnetic recording layer is performed.
    Type: Grant
    Filed: March 22, 2013
    Date of Patent: July 28, 2015
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Junichi Yasumori, Yoshiaki Sonobe
  • Publication number: 20150188034
    Abstract: A magnetic tunnel junction device includes: a first magnetic layer that has an easy axis vertical to a surface; a non-magnetic layer on the first magnetic layer; and a second magnetic layer that has an easy axis vertical to a surface on the non-magnetic layer, and an interface layer formed of a Heussler alloy between the non-magnetic layer and at least one of the first and second magnetic layers. The at least one of the first and second magnetic layers is formed of MnGa. A lattice constant of the interface layer parallel to a major surface thereof in a bulk state thereof is between a lattice constant of the non-magnetic layer parallel to a major surface thereof in a bulk state thereof and a lattice constant of the at least one of the first and second magnetic layers parallel to a major surface thereof in a bulk state thereof.
    Type: Application
    Filed: December 22, 2014
    Publication date: July 2, 2015
    Inventors: Shigeki Takahashi, Yoshiaki Sonobe, Koki Takanashi
  • Patent number: 9005699
    Abstract: A method for manufacturing a magnetic recording medium includes the steps of (a) forming a perpendicular magnetic recording layer and (b) applying an ion beam to regions between tracks of the perpendicular magnetic recording layer so as to form separation regions for magnetically separating the tracks from each other. In the step (a), a continuous film layer composed of a multilayer film is formed, and CoB layers and Pd layers are laminated in the multilayer film. In the step (b), the CoB layers and the Pd layers are melted by the ion beam so as to form an alloy of metals contained in the CoB layers and the Pd layers to thereby form the separation regions.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: April 14, 2015
    Assignee: WD Media, LLC
    Inventors: Yoshiaki Sonobe, Teiichiro Umezawa, Koichi Wago
  • Patent number: 8795790
    Abstract: [Problem] An object is to provide a magnetic recording medium with improved HDI characteristics, such as impact resistance, and its manufacturing method. [Solution] A typical structure of a magnetic recording medium 100 according to the present invention includes, on a base, at least a magnetic recording layer 122, a protective layer 126, and a lubricating layer 128, wherein the magnetic recording layer 122 includes, in an in-plane direction, a magnetic recording part 136 configured of a magnetic material and a non-recording part 134 magnetically separating the magnetic recording part 136, and a surface corresponding to the non-recording part 134 protuberates more than a surface corresponding to the magnetic recording part 136.
    Type: Grant
    Filed: December 9, 2009
    Date of Patent: August 5, 2014
    Assignee: WD Media (Singapore) Pte. Ltd.
    Inventors: Yoshiaki Sonobe, Akira Shimada, Tsuyoshi Ozawa, Masanori Aniya