Patents by Inventor Masato Shiimoto

Masato Shiimoto 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: 8223463
    Abstract: A magnetoresistive head which has a high head SNR by reducing generated mag-noise without deteriorating an output comprises, according to one embodiment, a magnetoresistive sensor having a laminated structure which includes an antiferromagnetic layer, a magnetization pinned layer, a non-magnetic intermediate layer, a magnetization free layer, and a magnetization stable layer arranged adjacent to the magnetization free layer. The magnetization stable layer comprises non-magnetic coupling layer, a first ferromagnetic stable layer, an antiparallel coupling layer, and a second ferromagnetic stable layer. A magnetization quantity of a first ferromagnetic stable layer and a second ferromagnetic stable layer are substantially equal, and the magnetization of the first ferromagnetic stable layer and the second ferromagnetic stable layer are magnetically coupled in the antiparallel direction from each other.
    Type: Grant
    Filed: October 15, 2009
    Date of Patent: July 17, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Hiroyuki Katada, Masato Shiimoto, Hiroyuki Hoshiya
  • Patent number: 8223464
    Abstract: In one embodiment, a differential-type magnetic read head includes a differential-type magneto-resistive-effect film formed on a substrate, and a pair of electrodes for applying current in a direction perpendicular to a film plane of the film. The film includes a first and second stacked film, each having a pinned layer, an intermediate layer, and a free layer, with the second stacked film being formed on the first stacked film. A side face in a track width direction of the film is shaped to have an inflection point at an intermediate position in a thickness direction of the film, and the side face is shaped to be approximately vertical to the substrate in an upward direction of the substrate from the inflection point. Also, the side face is shaped to be gradually increased in track width as approaching the substrate in a downward direction of the substrate from the inflection point.
    Type: Grant
    Filed: November 9, 2009
    Date of Patent: July 17, 2012
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Kan Yasui, Masato Shiimoto, Takeshi Nakagawa, Hiroyuki Katada, Nobuo Yoshida, Hiroyuki Hoshiya
  • Publication number: 20120147502
    Abstract: Minute elements are formed while a photo deviation is suppressed between a spin torque oscillator and a main pole and damage is prevented on the ends of the spin torque oscillator in microwave-assisted recording. A magnetic recording head used for microwave-assisted recording includes: a main pole; a spin torque oscillator that is disposed on the main pole and includes a magnetization high-speed rotation layer for rotating magnetization at a high speed by a spin torque; a protective film that is disposed in the track width direction of the spin torque oscillator; an insulating film formed over the wall surfaces of the main pole and the wall surfaces of the protective film; and a magnetic film formed on the insulating film so as to cover at least the main pole.
    Type: Application
    Filed: December 6, 2011
    Publication date: June 14, 2012
    Applicant: HITACHI, LTD.
    Inventors: Yuta Udo, Mikito Sugiyama, Masato Shiimoto, Nobuo Yoshida, Kenji Sugiura, Masashi Hattori
  • Publication number: 20120120518
    Abstract: In a conventional type magnetic head that performs microwave assisted recording, since a difference in a demagnetizing field between an end and the center of a field generation layer (FGL) grows larger when saturation magnetization of the FGL grows larger, the FGL that generates a microwave is not oscillated in a state of a single domain. Then, a spin-torque oscillator according to the present invention used for a magnetic head for microwave assisted recording is provided with at least one fixed layer, one non-magnetic intermediate layer and one alternating-current magnetic field generation layer respectively and is provided with a structure where saturation magnetization at ends of a film except an end in a direction from an air bearing surface to a surface opposite to it is made smaller than saturation magnetization in the center of the film of the alternating-current magnetic field generation layer.
    Type: Application
    Filed: November 15, 2011
    Publication date: May 17, 2012
    Inventors: Masato Matsubara, Masato Shiimoto, Hiroyuki Katada, Keiichi Nagasaka
  • Publication number: 20120113542
    Abstract: The present invention provides a magnetic recording head and a magnetic recording device that realize information transfer speed exceeding 1 Gbit/s in microwave assisted magnetic recording applied to a magnetic recording device having recording density exceeding 1 Tbit/in2. Concerning a reference layer that supplies spin torque to a high-speed magnetization rotator serving as a microwave field generation source, when an externally applied field to the reference layer is represented as Hext, a magnetic anisotropy field of the reference layer is represented as Hk, and an effective demagnetizing field in a vertical direction of a film surface of the reference layer is represented as Hd-eff, the fixing layer is configured to satisfy conditions Hext?Hk+Hd-eff>0 and Hext+Hk?Hd-eff>0.
    Type: Application
    Filed: November 2, 2011
    Publication date: May 10, 2012
    Inventors: Masukazu Igarashi, Yo Sato, Masato Shiimoto, Keiichi Nagasaka
  • Publication number: 20120113543
    Abstract: A magnetic recording head enabling both enhancement of a strength of a magnetic field from a main pole and provision of narrow-track recording to achieve a high recording density in a high-frequency magnetic field-assisted recording method is provided. An oscillator 110 that generates a high-frequency magnetic field is provided on the trailing side of a main pole 120, and viewed from the air bearing surface side, a ratio Pw/Two between a track width Pw of a trailing-side edge portion of the main pole and a track width Two of a leading-side edge portion of the oscillator is no less than 0.85 and no more than 1.25, and the main pole includes a part having a track width larger than Pw between the trailing-side edge portion and a leading-side edge portion of the main pole.
    Type: Application
    Filed: November 8, 2011
    Publication date: May 10, 2012
    Applicant: HITACHI, LTD.
    Inventors: Masato Shiimoto, Mikito Sugiyama
  • Publication number: 20120069465
    Abstract: The present invention provides a spin torque oscillator that can realize stable oscillation and has high reliability. A laminated structure including a first magnetic layer 1 having a bcc crystal structure and having in-plane magnetic anisotropy and a second magnetic layer 2 having perpendicular magnetic anisotropy laminated on the first magnetic layer 1 and including a multilayer film of Co and Ni is used.
    Type: Application
    Filed: August 12, 2011
    Publication date: March 22, 2012
    Applicant: HITACHI, LTD.
    Inventors: Yo SATO, Keiichi NAGASAKA, Masato SHIIMOTO, Masato MATSUBARA
  • Publication number: 20110216435
    Abstract: A microwave-assisted magnetic recording head includes: a main magnetic pole that generates a recording magnetic field to be recorded on a magnetic recording medium; a shield; and an oscillator that is provided between the main magnetic pole and the shield and generates a microwave magnetic field. The microwave-assisted magnetic recording head is provided with a thermal expansion device for adjusting a relative position between the oscillator and the main magnetic pole so as to be able to independently adjust a recording magnetic field from the main magnetic pole and a microwave magnetic field from the oscillator.
    Type: Application
    Filed: February 1, 2011
    Publication date: September 8, 2011
    Applicant: Hitachi, Ltd.
    Inventors: MASATO SHIIMOTO, Masakazu Igarashi, Masaru Furukawa
  • Publication number: 20110181987
    Abstract: Provided is a differential type reproduction head which can obtain a preferable bit error rate without causing a baseline shift even when two magnetoresistive elements have different maximum resistance change amounts. The differential type reproduction head has a layered structure formed by a first magnetoresistive element having a first free layer, a differential gap layer, and a second magnetoresistive element having a second free layer. When DR1 and DR2 are the maximum resistance change amounts of the first magnetoresistive element and the second magnetoresistive element, respectively, HB1 is a magnetic domain control field applied to the first free layer, and HB2 is a magnetic domain control field applied to the second free layer, the following relationships are satisfied: HB1>HB2 when DR1>DR2; HB2>HB1 when DR2>DR1.
    Type: Application
    Filed: May 19, 2009
    Publication date: July 28, 2011
    Applicant: HITACHI, LTD.
    Inventors: Masato Shiimoto, Hiroyuki Katada, Takeshi Nakagawa, Kan Yasui, Yo Sato
  • Publication number: 20110134564
    Abstract: A magnetic head, according to one embodiment, includes a sensor film, a sensor cap film provided above the sensor film, a pair of shields including an upper magnetic shield and a lower magnetic shield which serve as electrodes that pass current in a film thickness direction of the sensor film, a track insulating film contacting both sides of the sensor film in the track width direction, a graded domain control film arranged on both sides in the track width direction of the sensor film adjacent the track insulating film, and an element height direction insulating film positioned on an opposite side of the sensor film relative to an air-bearing surface, wherein an edge position of the element height direction insulating film adjacent the sensor film on the air-bearing surface side is substantially the same as an edge position of the sensor cap film in the element height direction.
    Type: Application
    Filed: November 30, 2010
    Publication date: June 9, 2011
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Nobuo Yoshida, Masato Shiimoto, Kenichi Akita, Kan Yasui
  • Publication number: 20100302688
    Abstract: According to one embodiment, a magnetoresistive effect head includes a lower magnetic shield provided on a substrate, a magnetoresistive effect film laminated from a pinned layer with a pinned direction of magnetization, an intermediate layer, a free layer having a varying direction of magnetization controlled by an applied external magnetic field, a magnetic domain control layer formed with an intervening insulation layer on both sides in a track width direction of the magnetoresistive effect film, an upper magnetic shield, and electrodes for directing sense current flow in a direction perpendicular to a film surface of the magnetoresistive effect film, wherein a magnetic field applied by the magnetic domain control layer to a region away from an ABS of the free layer is at least 1.4 times larger than a magnetic field applied by the magnetic domain control layer to a region near the ABS of the free layer.
    Type: Application
    Filed: May 20, 2010
    Publication date: December 2, 2010
    Inventors: Masato Shiimoto, Kan Yasui, Nobuo Yoshida, Hiroyuki Takazawa
  • Publication number: 20100142101
    Abstract: According to one embodiment, a differential magnetoresistive effect element comprises a first magnetoresistive effect element having a first pinning layer, a first intermediate layer, and a first free layer. The differential magnetoresistive effect element also comprises a second magnetoresistive effect element stacked via a spacer layer above the first magnetoresistive effect element, the second magnetoresistive effect element having a second pinning layer, a second intermediate layer, and a second free layer. The first magnetoresistive effect element and the second magnetoresistive effect element show in-opposite-phase resistance change in response to a magnetic field in the same direction, and tp2>tp1 is satisfied when a thickness of the first pinning layer is tp1, and a thickness of the second pinning layer is tp2. In another embodiment, the first and second magnetoresistive effect elements may be CPP-GMR elements.
    Type: Application
    Filed: December 1, 2009
    Publication date: June 10, 2010
    Inventors: Yo Sato, Katsumi Hoshino, Masato Shiimoto, Takeshi Nakagawa, Hiroyuki Hoshiya
  • Publication number: 20100118448
    Abstract: In one embodiment, a differential-type magnetic read head includes a differential-type magneto-resistive-effect film formed on a substrate, and a pair of electrodes for applying current in a direction perpendicular to a film plane of the film. The film includes a first and second stacked film, each having a pinned layer, an intermediate layer, and a free layer, with the second stacked film being formed on the first stacked film. A side face in a track width direction of the film is shaped to have an inflection point at an intermediate position in a thickness direction of the film, and the side face is shaped to be approximately vertical to the substrate in an upward direction of the substrate from the inflection point. Also, the side face is shaped to be gradually increased in track width as approaching the substrate in a downward direction of the substrate from the inflection point.
    Type: Application
    Filed: November 9, 2009
    Publication date: May 13, 2010
    Inventors: Kan Yasui, Masato Shiimoto, Takeshi Nakagawa, Hiroyuki Katada, Nobuo Yoshida, Hiroyuki Hoshiya
  • Publication number: 20100091416
    Abstract: A magnetoresistive head which has a high head SNR by reducing generated mag-noise without deteriorating an output comprises, according to one embodiment, a magnetoresistive sensor having a laminated structure which includes an antiferromagnetic layer, a magnetization pinned layer, a non-magnetic intermediate layer, a magnetization free layer, and a magnetization stable layer arranged adjacent to the magnetization free layer. The magnetization stable layer comprises non-magnetic coupling layer, a first ferromagnetic stable layer, an antiparallel coupling layer, and a second ferromagnetic stable layer. A magnetization quantity of a first ferromagnetic stable layer and a second ferromagnetic stable layer are substantially equal, and the magnetization of the first ferromagnetic stable layer and the second ferromagnetic stable layer are magnetically coupled in the antiparallel direction from each other.
    Type: Application
    Filed: October 15, 2009
    Publication date: April 15, 2010
    Inventors: Hiroyuki Katada, Masato Shiimoto, Hiroyuki Hoshiya
  • Publication number: 20090207531
    Abstract: A magnetic recording read head is provided capable of achieving high reproduction output, resolution, and SNR, even at a high linear density. There is also provided a magnetic recording and reproducing device capable of achieving sufficient error bit rate. The magnetic recording read head includes a differential read head and a write head. The differential read head has a multilayer structure formed by laminating a first magnetoresistive sensor having a first free layer, a differential gap layer, and a second magnetoresistive sensor having a second free layer. Outside the multilayer structure, a pair of electrodes and a pair of magnetic shields are provided respectively. A ratio (Gl/bl) of an inside distance (Gl) between the first and second free layers to a bit length (bl) is set to 0.6 or more and 1.6 or less.
    Type: Application
    Filed: February 4, 2009
    Publication date: August 20, 2009
    Inventors: Masato SHIIMOTO, Takeshi Nakagawa, Hiroyuki Katada, Naoto Ito, Kenichi Meguro
  • Publication number: 20080182133
    Abstract: Embodiments of the present invention help to reduce mag-noise in a magnetoresistive head without deterioration in reproduced output and improve the signal/noise ratio (SNR) of the magnetoresistive head. According to one embodiment, the magnetoresistive head uses a synthetic ferri free layer and it is arranged such that the magnetic field which is applied to an end of a free layer with smaller film thickness and saturation magnetization in the track width direction by a coupling field is larger than the magnetic field which is applied to it by a bias layer.
    Type: Application
    Filed: January 25, 2008
    Publication date: July 31, 2008
    Inventors: Masato Shiimoto, Hiroyuki Katada, Kazuhiro Nakamoto, Hiroyuki Hoshiya