Patents by Inventor Masukazu Igarashi

Masukazu Igarashi 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).

  • Patent number: 9437222
    Abstract: A magnetic oscillator for use in Microwave Assisted Magnetic Recording (MAMR). The magnetic oscillator can be a spin torque oscillator and includes a magnetic spin polarization layer, a magnetic field generation layer and a non-magnetic intermediate layer sandwiched between the magnetic spin polarization layer and the magnetic field generation layer. The non-magnetic intermediate layer is constructed of a material that provides improved performance, increased lifespan and thermal robustness. The magnetic intermediate layer is constructed of an alloy of Ag and an element X. More preferably the element X can be Sn or Zn.
    Type: Grant
    Filed: May 30, 2015
    Date of Patent: September 6, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Susumu Okamura, Masao Shiimoto, Katsuro Watanabe, Masashige Sato, Keiichi Nagasaka, Yo Sato, Masukazu Igarashi
  • Patent number: 9378759
    Abstract: Embodiments disclosed herein generally relate to a magnetic disk device employing a MAMR head. The MAMR head includes an STO. The STO comprises an underlayer, an SPL, an interlayer, an FGL, and a capping layer. The SPL is comprised of a high perpendicular magnetic anisotropy material. The SPL has a large effective perpendicular magnetic anisotropy field, and the SPL has a lower magnetic moment than the FGL. An applied current is adapted to flow in a direction from the FGL to the SPL resulting in the magnetization direction of the SPL being almost perpendicular to the FGL and anti-parallel to a head-gap magnetic field due to a relation between a first spin torque directed from the SPL to the FGL and a second spin torque directed from the FGL to the SPL.
    Type: Grant
    Filed: November 20, 2014
    Date of Patent: June 28, 2016
    Assignee: HGST NETHERLANDS B.V.
    Inventors: Keiichi Nagasaka, Yo Sato, Masashige Sato, Susumu Okamura, Masato Shiimoto, Masukazu Igarashi
  • Publication number: 20160148627
    Abstract: Embodiments disclosed herein generally relate to a magnetic disk device employing a MAMR head. The MAMR head includes an STO. The STO comprises an underlayer, an SPL, an interlayer, an FGL, and a capping layer. The SPL is comprised of a high perpendicular magnetic anisotropy material. The SPL has a large effective perpendicular magnetic anisotropy field, and the SPL has a lower magnetic moment than the FGL. An applied current is adapted to flow in a direction from the FGL to the SPL resulting in the magnetization direction of the SPL being almost perpendicular to the FGL and anti-parallel to a head-gap magnetic field due to a relation between a first spin torque directed from the SPL to the FGL and a second spin torque directed from the FGL to the SPL.
    Type: Application
    Filed: November 20, 2014
    Publication date: May 26, 2016
    Inventors: Keiichi NAGASAKA, Yo SATO, Masashige SATO, Susumu OKAMURA, Masato SHIIMOTO, Masukazu IGARASHI
  • Patent number: 9336797
    Abstract: The present disclosure generally relates to a high-frequency oscillator for use in a recording device having a microwave-assisted magnetic recording head. The microwave-assisted magnetic recording head achieves a large assist effect by using an extended spin torque oscillator disposed between a main magnetic pole and a pole opposite the main magnetic pole. The spin torque oscillator obtains a strong high-frequency magnetic field and comprises a first non-magnetic spin scatterer, a reference layer, a first non-magnetic spin transfer layer, a first magnetic field generating layer, a second non-magnetic spin transfer layer, a second magnetic field generating layer, and a second non-magnetic spin scatterer. The spin torque oscillator has a drive current flowing though in the direction from the first magnetic field generating layer to the reference layer.
    Type: Grant
    Filed: May 29, 2014
    Date of Patent: May 10, 2016
    Assignee: HGST NETHERLANDS B.V.
    Inventors: Masukazu Igarashi, Masato Matsubara, Keiichi Nagasaka, Yo Sato, Masato Shiimoto, Masashige Sato
  • Patent number: 9311934
    Abstract: Embodiments disclosed herein generally relate to a MAMR head. The MAMR head includes an STO and a current switching system electrically coupled to the STO. The current switching system can be used to optimize the STO frequency by changing the STO bias polarity, i.e., by changing the direction of the current flowing to the STO. As a result, the difference between the STO frequency and the magnetic media frequency is minimized, which improves recording capability of the MAMR head.
    Type: Grant
    Filed: July 24, 2015
    Date of Patent: April 12, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Masashige Sato, Masukazu Igarashi, Yo Sato, Masato Matsubara
  • Patent number: 9305574
    Abstract: Embodiments disclosed herein generally relate to a MAMR head. The MAMR head includes an STO. The STO has a first magnetic layer, a second magnetic layer and an interlayer disposed between the first and second magnetic layers. One of the first and second magnetic layers is made of a negative polarization material while the other magnetic layer is made of a positive polarization material. As a result, the magnetizations in the first and second magnetic layers are in the same direction when in oscillation, which suppresses the partial cancellation of the magnetizations in the first and second magnetic layers and strengthens the AC magnetic field.
    Type: Grant
    Filed: September 23, 2014
    Date of Patent: April 5, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Keiichi Nagasaka, Yo Sato, Masato Shiimoto, Masashige Sato, Masukazu Igarashi, Susumu Okamura
  • Patent number: 9305586
    Abstract: A magnetic head, according to one embodiment, includes a magnetized high-speed rotor placed in the vicinity of a main magnetic pole, wherein the main magnetic pole generates a magnetized rotating magnetic field, wherein information is recorded by generating a high-frequency magnetic field from the magnetized high-speed rotor and switching the magnetic head between a magnetic resonance state and a magnetization state, and wherein the magnetic head has a structure such that leaking is reduced for magnetic fields applied parallel to a magnetized rotating surface of the magnetized high-speed rotor from the main magnetic pole. Additional systems and methods are also presented.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: April 5, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Masafumi Mochizuki, Masukazu Igarashi
  • Publication number: 20160086623
    Abstract: Embodiments disclosed herein generally relate to a MAMR head. The MAMR head includes an STO. The STO has a first magnetic layer, a second magnetic layer and an interlayer disposed between the first and second magnetic layers. One of the first and second magnetic layers is made of a negative polarization material while the other magnetic layer is made of a positive polarization material. As a result, the magnetizations in the first and second magnetic layers are in the same direction when in oscillation, which suppresses the partial cancellation of the magnetizations in the first and second magnetic layers and strengthens the AC magnetic field.
    Type: Application
    Filed: September 23, 2014
    Publication date: March 24, 2016
    Inventors: Keiichi NAGASAKA, Yo SATO, Masato SHIIMOTO, Masashige SATO, Masukazu IGARASHI, Susumu OKAMURA
  • Patent number: 9275672
    Abstract: A microwave assisted magnetic recording head includes a recording magnetic pole unit that produces a recording field for writing to a perpendicular magnetic recording medium, and a high-frequency magnetic field oscillator that produces a high-frequency magnetic field. The recording magnetic pole unit includes a magnetic core with a write gap portion at which a main recording field component is concentrated, and the high-frequency magnetic field oscillator is disposed in the write gap.
    Type: Grant
    Filed: February 8, 2013
    Date of Patent: March 1, 2016
    Assignee: HITACHI, LTD.
    Inventors: Yoshihiro Shiroishi, Hiroshi Fukuda, Harukazu Miyamoto, Junko Ushiyama, Katsuro Watanabe, Yoshiyuki Hirayama, Masukazu Igarashi
  • Patent number: 9230569
    Abstract: In one embodiment, a magnetic head includes a main magnetic pole positioned configured to generate a writing magnetic field when current is applied to a write coil, and a spin torque oscillator (STO) located adjacent the main magnetic pole, the STO being configured to generate a high frequency magnetic field when current is applied thereto, wherein the high frequency magnetic field is generated simultaneously to the writing magnetic field to assist in reversing magnetization of a magnetic recording medium. The STO includes: a spin polarization layer (SPL), a field generation layer (FGL) positioned adjacent the SPL, and one or more interlayers positioned between the SPL and the FGL, and a magnetization easy axis of the SPL is positioned in an in-plane direction such that the SPL has no perpendicular magnetic anisotropy.
    Type: Grant
    Filed: November 26, 2014
    Date of Patent: January 5, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Masato Shimoto, Masukazu Igarashi, Keiichi Nagasaka, Yo Sato, Susumu Okamura, Masashige Sato
  • Publication number: 20150348574
    Abstract: The present disclosure generally relates to a high-frequency oscillator for use in a recording device having a microwave-assisted magnetic recording head. The microwave-assisted magnetic recording head achieves a large assist effect by using an extended spin torque oscillator disposed between a main magnetic pole and a pole opposite the main magnetic pole. The spin torque oscillator obtains a strong high-frequency magnetic field and comprises a first non-magnetic spin scatterer, a reference layer, a first non-magnetic spin transfer layer, a first magnetic field generating layer, a second non-magnetic spin transfer layer, a second magnetic field generating layer, and a second non-magnetic spin scatterer. The spin torque oscillator has a drive current flowing though in the direction from the first magnetic field generating layer to the reference layer.
    Type: Application
    Filed: May 29, 2014
    Publication date: December 3, 2015
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Masukazu IGARASHI, Masato MATSUBARA, Keiichi NAGASAKA, Yo SATO, Masato SHIIMOTO, Masashige SATO
  • Patent number: 9099107
    Abstract: In one embodiment, a spin torque oscillator (STO) includes a reference layer having a magnetization that is capable of free in-plane rotation, a field generation layer (FGL) including at least one magnetic film having an easy magnetization plane effectively in a film plane, wherein a magnetization of the FGL is capable of in-plane rotation, and a stabilizing layer (STL) positioned on a side of the FGL opposite the reference layer, the STL including a magnetic film having an easy magnetization plane effectively in a film plane, wherein a magnetization of the STL is capable of in-plane rotation, wherein a product of a saturation magnetization of the STL multiplied by a thickness of the STL is less than half a product of a magnetization of the FGL multiplied by a thickness of the FGL.
    Type: Grant
    Filed: January 23, 2015
    Date of Patent: August 4, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Masukazu Igarashi, Keiichi Nagasaka, Susumu Okamura, Yo Sato, Masashige Sato, Masato Shimoto
  • Patent number: 9007721
    Abstract: A spin torque oscillator is provided which is adapted to high data transfer rates and which can perform assisted magnetic recording of sufficient magnitude. A spin torque oscillator is provided with a stacked spin injection layer and a high frequency magnetic field generation layer. The stacked spin injection layer has a stacked structure in which a first magnetic layer, a coupling layer, and a second magnetic layer are stacked in the order mentioned from a far side as viewed from the high frequency magnetic field generation layer. Magnetization of the first magnetic layer and magnetization of the second magnetic layer are coupled antiparallel to each other. A polarity of the magnetization of the second magnetic layer is reversed temporally earlier than a magnetic field polarity reversal of a leakage magnetic field from the main magnetic pole.
    Type: Grant
    Filed: August 2, 2013
    Date of Patent: April 14, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Yo Sato, Katsuro Watanabe, Keizou Katou, Masukazu Igarashi
  • Patent number: 9007722
    Abstract: To uniformly determine the positional relationship between a main magnetic pole and a spin torque oscillator while independently optimizing the main magnetic pole and the spin torque oscillator. On a trailing end surface of a main magnetic pole, a step is provided at the boundary between the main magnetic pole and a gap material disposed on both sides thereof, and a spin torque oscillator is formed on the step. The spin torque oscillator is effectively separated into two regions by utilizing the step. Further, a part of the spin torque oscillator is removed so as to disable the unwanted region, thereby realizing a self-alignment type high frequency magnetic field assisted magnetic recording head structure such that the positions of the end portions of the main magnetic pole and the spin torque oscillator are aligned.
    Type: Grant
    Filed: August 16, 2013
    Date of Patent: April 14, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Junichiro Shimizu, Kikuo Kusukawa, Yo Sato, Masukazu Igarashi
  • Patent number: 9007723
    Abstract: In one embodiment, a microwave-assisted magnetic recording (MAMR) head includes a main pole configured to write data to a magnetic medium using a write magnetic field, a write coil, wherein the write magnetic field is produced by the main pole upon a recording current, Iw, being provided to the write coil, and a spin torque oscillator (STO) positioned near the main pole, the STO being configured to provide a high-frequency assistance magnetic field to the magnetic medium upon a STO drive current, ISTO, being provided to the STO, wherein the STO drive current, ISTO, is ramped-up prior to the recording current, Iw, being provided to the write coil in order to begin a write operation for writing data to the magnetic medium. A method of operation for the MAMR head and an apparatus including the MAMR head are also described according to additional embodiments.
    Type: Grant
    Filed: December 13, 2013
    Date of Patent: April 14, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Masukazu Igarashi, Masato Shiimoto, Masato Matsubara, Yo Sato, Kenji Sugiura
  • Patent number: 8937789
    Abstract: To suppress a spread of not only a recording magnetic field generated from a main pole but also a high-frequency magnetic field generated from a spin torque oscillator in a microwave assisted magnetic recording head. The main pole and the spin torque oscillator are surrounded by a trailing shield layer and are also surrounded by a side/leading shield layer with an insulator sidegap layer interposed therebetween, and a high-frequency magnetic field shield layer, which absorbs a high-frequency magnetic field generated from the spin torque oscillator, is arranged in at least part of the shield layers.
    Type: Grant
    Filed: June 7, 2013
    Date of Patent: January 20, 2015
    Assignee: Hitachi, Ltd.
    Inventors: Katsuro Watanabe, Masukazu Igarashi
  • Patent number: 8883327
    Abstract: Provided is a magnetic recording medium achieving both of reduction in switching field distribution and reduction in switching field intensity by high-frequency magnetic field, thus enabling high-density recording. Magnetic grains of the magnetic recording medium are made up of a recording layer and a resonance layer. The resonance layer is disposed closer to a protective layer 5 than the recording layer, and a magnetic material of the recording layer has anisotropy field 1.2 times or more anisotropy field of a magnetic material of the resonance layer. The magnetic material of the recording layer has saturation magnetization substantially equal to saturation magnetization of the magnetic material of the resonance layer. At the entire resonance layer and a part of the recording layer, the magnetic grains are separated from surrounding magnetic grains by a nonmagnetic material, and at a part of the recording layer, the magnetic grains are coupled with surrounding magnetic grains.
    Type: Grant
    Filed: March 13, 2013
    Date of Patent: November 11, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshiyuki Hirayama, Masukazu Igarashi, Katsuro Watanabe
  • Patent number: 8879205
    Abstract: In one embodiment, a MAMR head includes a main magnetic pole, a STO positioned near the main magnetic pole, the STO including a first perpendicular magnetic layer positioned above the main magnetic pole, wherein the first perpendicular magnetic layer is a first spin polarization layer having an axis of magnetic anisotropy in a direction perpendicular to a film surface, a first non-magnetic transmission layer positioned above the first perpendicular magnetic layer, a magnetic layer effectively having a plane of easy magnetization in the film surface positioned above the first non-magnetic transmission layer, the magnetic layer being a FGL, a second non-magnetic transmission layer positioned above the magnetic layer, and a second perpendicular magnetic layer positioned above the second non-magnetic transmission layer, wherein the second perpendicular magnetic layer is a second spin polarization layer having magnetic anisotropy in the direction perpendicular to the film plane.
    Type: Grant
    Filed: November 13, 2012
    Date of Patent: November 4, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Keiichi Nagasaka, Masukazu Igarashi
  • Patent number: 8854768
    Abstract: To realize a highly reliable magnetic head for a high-frequency magnetic field assisted recording system by preventing current crowding in an oscillator and increasing the current resistance of the oscillator. Between a main pole that generates a recording magnetic field and a trailing shield, an oscillator that includes a non-magnetic metal layer, a spin injection pinned layer, an intermediate layer, and a high-frequency magnetic field generation layer and that generates a high-frequency magnetic field is disposed. The non-magnetic metal layer adjacent to the main pole is tapered with the width gradually increasing from the trailing side toward the leading side.
    Type: Grant
    Filed: January 29, 2014
    Date of Patent: October 7, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Kenji Sugiura, Yo Sato, Masukazu Igarashi, Katsuro Watanabe
  • Patent number: 8830627
    Abstract: In a magnetic head of a high-frequency magnetic field assisted recording system, a width of a high-frequency magnetic field from an oscillator is decreased to enhance an oscillation frequency, in order to realize a high-density recording. An oscillator provided near a main pole, which generates a recording magnetic field, for generating a high-frequency magnetic field is patterned by a conventional photolithography, and then, an oxidation, nitridation, or oxynitridation is performed on the side face in a track width direction. With this process, an oxide layer, a nitride layer, or an oxynitride layer, which is made of a material of the oscillator, is formed on the side face of the oscillator in the track width direction, and the shape of the oscillator is formed to be semi-circular.
    Type: Grant
    Filed: January 7, 2013
    Date of Patent: September 9, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Kenji Sugiura, Katsuro Watanabe, Masukazu Igarashi, Yo Sato