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: 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: 9007724
    Abstract: Embodiments disclosed herein generally relate to the data storage field and hard disk drives (HDD) using microwave assisted magnetic recording (MAMR) technology. Aspects of the preferred embodiments are to prevent the breakdown of spin torque oscillators (STO) due to large amounts of current flowing through the STO during head/disk contact. A magnetic head slider is disposed above and spaced apart from a disk. A STO is formed on a section of the magnetic head slider. Two electrodes are coupled to the STO, and one electrode has a higher potential than the other electrode. A preamplifier is adapted to send a current through the two electrodes, resulting in the higher potential electrode protruding closer to the disk than the lower potential electrode. Current then flows from one electrode to the disk without flowing through the STO, and breakdown of the STO is prevented.
    Type: Grant
    Filed: June 12, 2014
    Date of Patent: April 14, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Masaru Furukawa, Junguo Xu, Masato Shiimoto, Jianhua Li
  • Publication number: 20150092303
    Abstract: Embodiments of the present invention generally include magnetoresistive heads, such as read heads, having a sensor structure and side shields disposed adjacent to the sensor structure. The distance between the side shields and the sensor structure increase in a direction from an ABS in the off-track direction. The magnetoresistive heads may include tapered surfaces on the side shields or sensor structure, or may include stepped surfaces on the side shields or sensor structure.
    Type: Application
    Filed: October 1, 2013
    Publication date: April 2, 2015
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Jun AOYAMA, Masahiko HATATANI, Hiroyuki KATADA, Masato SHIIMOTO
  • Publication number: 20150092292
    Abstract: Embodiments of the present invention generally relate to a microwave assisted magnetic recording (MAMR) head. The MAMR head includes a main pole, a trailing shield, and a spin torque oscillator (STO) disposed between the main pole and the trailing shield. The STO is recessed from an air bearing surface.
    Type: Application
    Filed: September 27, 2013
    Publication date: April 2, 2015
    Applicant: HGST Netherlands B.V.
    Inventors: Masaru FURUKAWA, Jianhua LI, Masato MATSUBARA, Masato SHIIMOTO
  • Patent number: 8988826
    Abstract: A microwave-assisted magnetic recording (MAMR) head according to one embodiment includes a main pole; a trailing shield positioned downstream from the main pole; an oscillation device adapted to generate a high-frequency magnetic field, the oscillation device being positioned between the main pole and the trailing shield; a circuit adapted to flow an electric current therethrough to the main pole, the oscillation device, and the trailing shield; an electrically conductive non-magnetic body positioned on one or more sides of the main pole in a cross-track direction and/or a leading direction; and an insulating non-magnetic body positioned on one or more sides of the electrically conductive non-magnetic body in the cross-track direction and/or the leading direction, wherein one or more edge portions of one side of the oscillation device and one or more edge portions of one side of the main pole are in direct contact with the electrically conductive non-magnetic body.
    Type: Grant
    Filed: December 20, 2012
    Date of Patent: March 24, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Mikito Sugiyama, Masato Shiimoto, Keiichi Nagasaka
  • Patent number: 8970996
    Abstract: A microwave assisted magnetic recording write head having a spin torque oscillator capable of producing high strength high frequency magnetic oscillations with reduced applied current. The spin torque oscillator uses a magnetic field generation layer with a high moment material including such as Fe and Co that is formed on an interlayer having a face centered cubic (fcc) crystal structure, that functions as an under-layer. The high moment magnetic field generation layer has also reduced magnetic damping.
    Type: Grant
    Filed: September 27, 2012
    Date of Patent: March 3, 2015
    Assignee: HSGT Netherlands B.V.
    Inventors: Keiichi Nagasaka, Masato Shiimoto, Masato Matsubara, Yuta Udou
  • Patent number: 8964332
    Abstract: Approaches to improving the signal-to-noise ratio in a microwave-assisted magnetic recording hard disk drive over the entire region from the inner diameter to the outer diameter of the disk, especially in the context of shingled magnetic recording, include a narrower side gap on the side opposing a spin torque oscillator offset direction than the side gap in the offset direction, thereby increasing the gradient of the recording magnetic field in the cross-track direction and reducing the track edge noise of the recording pattern. Embodiments include use of a side shield on the side opposing the offset direction that has a higher saturation magnetization than the side shield on the side in the offset direction, thereby further increasing the gradient of the recording magnetic field in the cross-track direction.
    Type: Grant
    Filed: September 30, 2013
    Date of Patent: February 24, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Hiroyuki Katada, Masato Shiimoto, Maki Maeda
  • Publication number: 20140347969
    Abstract: A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.
    Type: Application
    Filed: May 21, 2013
    Publication date: November 27, 2014
    Applicant: HGST Netherlands B.V.
    Inventors: Yasutaka Nishida, Masato Shiimoto, Hiroyuki Katada, Ikuya Tagawa, Junguo Xu
  • 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: 8848317
    Abstract: A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: September 30, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Ikuya Tagawa, Yasutaka Nishida, Hiroyuki Katada
  • Patent number: 8824103
    Abstract: The strength of a magnetic field applied from a main pole to an oscillator and the strength of a magnetic field applied from the main pole to a recording medium are improved in a magnetic recording head for microwave assisted recording. In the magnetic recording head according to the present invention, an interval between the main pole and a trailing shield at a place in a position above an air bearing surface is larger than an interval between the main pole and the trailing shield on the air bearing surface.
    Type: Grant
    Filed: February 24, 2012
    Date of Patent: September 2, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masato Shiimoto, Kenji Sugiura, Mikito Sugiyama, Isao Nunokawa, Yo Sato, Katsuro Watanabe, Kazuhiko Hosomi, Nobuo Yoshida
  • Patent number: 8773822
    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: Grant
    Filed: November 15, 2011
    Date of Patent: July 8, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masato Matsubara, Masato Shiimoto, Hiroyuki Katada, Keiichi Nagasaka
  • Publication number: 20140177092
    Abstract: A microwave-assisted magnetic recording (MAMR) head according to one embodiment includes a main magnetic pole adapted to generate a writing magnetic field when current is applied to a write coil; a trailing shield positioned, at an air bearing surface (ABS), in a trailing direction from the main magnetic pole; and a field generation layer (FGL) positioned, at the ABS, between the main magnetic pole and the trailing shield, wherein either a portion of the main magnetic pole closer to the FGL or a portion of the trailing shield closer to the FGL is adapted to act as a spin polarization layer.
    Type: Application
    Filed: December 20, 2012
    Publication date: June 26, 2014
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Hiroyuki Katada, Masato Shiimoto
  • Publication number: 20140177100
    Abstract: A microwave-assisted magnetic recording (MAMR) head according to one embodiment includes a main pole; a trailing shield positioned downstream from the main pole; an oscillation device adapted to generate a high-frequency magnetic field, the oscillation device being positioned between the main pole and the trailing shield; a circuit adapted to flow an electric current therethrough to the main pole, the oscillation device, and the trailing shield; an electrically conductive non-magnetic body positioned on one or more sides of the main pole in a cross-track direction and/or a leading direction; and an insulating non-magnetic body positioned on one or more sides of the electrically conductive non-magnetic body in the cross-track direction and/or the leading direction, wherein one or more edge portions of one side of the oscillation device and one or more edge portions of one side of the main pole are in direct contact with the electrically conductive non-magnetic body.
    Type: Application
    Filed: December 20, 2012
    Publication date: June 26, 2014
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Mikito Sugiyama, Masato Shiimoto, Keiichi Nagasaka
  • Publication number: 20140177105
    Abstract: A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.
    Type: Application
    Filed: December 21, 2012
    Publication date: June 26, 2014
    Applicant: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Ikuya Tagawa, Yasutaka Nishida, Hiroyuki Katada
  • Publication number: 20140133048
    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: Application
    Filed: November 13, 2012
    Publication date: May 15, 2014
    Applicant: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Keiichi Nagasaka, Masukazu Igarashi
  • Patent number: 8705206
    Abstract: A magnetic data storage system according to one embodiment includes a magnetic head adapted to record data according to a shingled magnetic recording (SMR) process. The magnetic head includes a main pole adapted to produce a writing magnetic field, a trailing shield positioned above a trailing side of the main pole, wherein a trailing gap is defined between the trailing shield and the main pole, and a spin torque oscillator (STO) positioned above a first trailing corner of the main pole at an STO-side of the main pole, wherein the trailing gap has a greater length in a film thickness direction near the STO-side of the main pole and a lesser length in the film thickness direction near a second trailing corner of the main pole opposite the first trailing corner in a track width direction of the main pole.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: April 22, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Maki Maeda, Masato Shiimoto, Hiroyuki Katada
  • Patent number: 8687319
    Abstract: A spin torque oscillator for microwave assisted recording includes a perpendicular free layer having a magnetic anisotropy axis in a direction perpendicular to a film surface, and an in-plane free layer composed of a magnetic film effectively having a magnetization easy plane on a film surface. When electric currents flows from the in-plane free layer side to the perpendicular free layer side, both free layers exchange spin information and thereby rotate their respective magnetizations almost antiparallel to each other and along a boundary surface with high-speed. Preferably, the perpendicular free layer is thinner than the in-plane free layer. It is also preferable that a magnetic anisotropy field of the perpendicular free layer attributable to materials should balance, in reverse directions, with an effective demagnetizing field in the perpendicular direction. Furthermore, the perpendicular free layer is preferably placed on the main pole side.
    Type: Grant
    Filed: February 24, 2012
    Date of Patent: April 1, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masukazu Igarashi, Masato Matsubara, Keiichi Nagasaka, Masato Shiimoto
  • Publication number: 20140085753
    Abstract: A microwave assisted magnetic recording write head having a spin torque oscillator capable of producing high strength high frequency magnetic oscillations with reduced applied current. The spin torque oscillator uses a magnetic field generation layer with a high moment material including such as Fe and Co that is formed on an interlayer having a face centered cubic (fcc) crystal structure, that functions as an under-layer. The high moment magnetic field generation layer has also reduced magnetic damping.
    Type: Application
    Filed: September 27, 2012
    Publication date: March 27, 2014
    Applicant: HGST NETHERLANDS B.V.
    Inventors: Keiichi Nagasaka, Masato Shiimoto, Masato Matsubara, Yuta Udou
  • Patent number: 8670201
    Abstract: In a magnetic recording device adopting a microwave assisted recording method, a microwave frequency on a positive polarity side and a microwave frequency on a negative polarity side are adjusted to be optimal. The magnetic recording device of the invention supplies to a magnetic head a write current of which a current waveform on the positive polarity side and a current waveform on the negative polarity side are asymmetric.
    Type: Grant
    Filed: February 23, 2012
    Date of Patent: March 11, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Masato Matsubara, Masato Shiimoto