Patents by Inventor Yoshihiko Seyama

Yoshihiko Seyama 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: 7441326
    Abstract: In a magnetic sensor, a lower terminal layer, a magnetosensitive layer, and a cover film are simultaneously patterned into substantially the same size. The opposing surface of the lower terminal layer, which opposes the magnetosensitive film is substantially superposed on one opposing surface of the magnetosensitive film. The opposing surface of the upper terminal layer, which opposes the magnetosensitive film is formed into a shape smaller than and included in the other opposing surface of the magnetosensitive film. This implements a magnetic sensor which uses a CPP structure and is yet readily processible and which includes a substantially accurate fine CPP structure in accordance with a desired output.
    Type: Grant
    Filed: August 17, 2006
    Date of Patent: October 28, 2008
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Atsushi Tanaka
  • Patent number: 7428127
    Abstract: A CPP magnetoresistive effect element includes a free magnetization layer, a fixed magnetization layer, and a plurality of conductive non-magnetic intermediate layers formed between the free magnetization layer and the fixed magnetization layer. An insulating layer and a magnetic layer including magnetic atoms are provided between any two of the non-magnetic intermediate layers.
    Type: Grant
    Filed: January 25, 2005
    Date of Patent: September 23, 2008
    Assignee: Fujitsu Limited
    Inventors: Keiichi Nagasaka, Yoshihiko Seyama, Hirotaka Oshima, Yutaka Shimizu, Atsushi Tanaka
  • Patent number: 7180713
    Abstract: A magnetoresistive element that detects a change of magnetoresistance by giving a sense current in the thickness direction of a magnetoresistive effect film including at least a base layer, a free layer, a non-magnetic layer, a pinned layer, a pinning layer, and a protection layer, includes a granular structure layer that includes conductive particles and an insulating matrix material in the form of a thin film containing the conductive particles in a dispersed state and having a smaller thickness than the particle diameter of the conductive particles, the granular structure layer being interposed between at least two adjacent layers among the base layer, the free layer, the non-magnetic layer, the pinned layer, the pinning layer, and the protection layer.
    Type: Grant
    Filed: October 16, 2002
    Date of Patent: February 20, 2007
    Assignee: Fujitsu Limited
    Inventors: Keiichi Nagasaka, Yoshihiko Seyama, Takahiko Sugawara, Yutaka Shimizu, Atsushi Tanaka
  • Publication number: 20060272146
    Abstract: In a magnetic sensor, a lower terminal layer, a magnetosensitive layer, and a cover film are simultaneously patterned into substantially the same size. The opposing surface of the lower terminal layer, which opposes the magnetosensitive film is substantially superposed on one opposing surface of the magnetosensitive film. The opposing surface of the upper terminal layer, which opposes the magnetosensitive film is formed into a shape smaller than and included in the other opposing surface of the magnetosensitive film. This implements a magnetic sensor which uses a CPP structure and is yet readily processible and which includes a substantially accurate fine CPP structure in accordance with a desired output.
    Type: Application
    Filed: August 17, 2006
    Publication date: December 7, 2006
    Inventors: Yoshihiko Seyama, Atsushi Tanaka
  • Patent number: 7130162
    Abstract: In a magnetic sensor, a lower terminal layer, a magnetosensitive layer, and a cover film are simultaneously patterned into substantially the same size. The opposing surface of the lower terminal layer, which opposes the magnetosensitive film is substantially superposed on one opposing surface of the magnetosensitive film. The opposing surface of the upper terminal layer, which opposes the magnetosensitive film is formed into a shape smaller than and included in the other opposing surface of the magnetosensitive film. This implements a magnetic sensor which uses a CPP structure and is yet readily processible and which includes a substantially accurate fine CPP structure in accordance with a desired output.
    Type: Grant
    Filed: February 20, 2001
    Date of Patent: October 31, 2006
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Atsushi Tanaka
  • Patent number: 7116533
    Abstract: A magnetoresistive sensor including the following layers, in order: a first conductor layer; a first antiferromagnetic layer; a first pinned ferromagnetic layer; a first nonmagnetic intermediate layer; a free ferromagnetic layer; a second nonmagnetic intermediate layer; a second pinned ferromagnetic layer; a second antiferromagnetic layer; and a second conductor layer. Alternatively, the magnetoresistive sensor may include the following layers, in order: a first conductor layer; a first free ferromagnetic layer; a first nonmagnetic intermediate layer; a first pinned ferromagnetic layer; an antiferromagnetic layer; a second pinned ferromagnetic layer; a second nonmagnetic intermediate layer; a second free ferromagnetic layer; and a second conductor layer.
    Type: Grant
    Filed: January 6, 2006
    Date of Patent: October 3, 2006
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu, Shin Eguchi, Hitoshi Kanai, Reiko Kondo, Hitoshi Kishi, Junya Ikeda
  • Publication number: 20060119989
    Abstract: Disclosed herein is a spin valve magnetoresistive sensor including a first conductor layer, a free ferromagnetic layer provided on the first conductor layer, a nonmagnetic intermediate layer provided on the free ferromagnetic layer, a pinned ferromagnetic layer provided on the nonmagnetic intermediate layer, an antiferromagnetic layer provided on the pinned ferromagnetic layer, and a second conductor layer provided on the antiferromagnetic layer. At least one of the free ferromagnetic layer and the pinned ferromagnetic layer has a thickness larger than that providing a maximum resistance change rate or resistance change amount in the case of passing a current in an in-plane direction of the at least one layer. That is, the thickness of at least one of the free ferromagnetic layer and the pinned ferromagnetic layer falls in the range of 3 nm to 12 nm.
    Type: Application
    Filed: January 6, 2006
    Publication date: June 8, 2006
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu, Shin Eguchi, Hitoshi Kanai, Reiko Kondo, Hitoshi Kishi, Junya Ikeda
  • Patent number: 6995960
    Abstract: Disclosed herein is a spin valve magnetoresistive sensor including a first conductor layer, a free ferromagnetic layer provided on the first conductor layer, a nonmagnetic intermediate layer provided on the free ferromagnetic layer, a pinned ferromagnetic layer provided on the nonmagnetic intermediate layer, an antiferromagnetic layer provided on the pinned ferromagnetic layer, and a second conductor layer provided on the antiferromagnetic layer. At least one of the free ferromagnetic layer and the pinned ferromagnetic layer has a thickness larger than that providing a maximum resistance change rate or resistance change amount in the case of passing a current in an in-plane direction of the at least one layer. That is, the thickness of at least one of the free ferromagnetic layer and the pinned ferromagnetic layer falls in the range of 3 nm to 12 nm.
    Type: Grant
    Filed: March 28, 2001
    Date of Patent: February 7, 2006
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu, Shin Eguchi, Hitoshi Kanai, Reiko Kondo, Hitoshi Kishi, Junya Ikeda
  • Patent number: 6927952
    Abstract: A magnetoresistive device includes a laminated film, and a mechanism for applying sense current in a direction of lamination in the laminated film, wherein the laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, the second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates the first and second ferromagnetic layer from each other.
    Type: Grant
    Filed: April 3, 2002
    Date of Patent: August 9, 2005
    Assignee: Fujitsu Limited
    Inventors: Yutaka Shimizu, Hirotaka Oshima, Keiichi Nagasaka, Yoshihiko Seyama, Atsushi Tanaka
  • Publication number: 20050152076
    Abstract: A CPP magnetoresistive effect element includes a free magnetization layer, a fixed magnetization layer, and a plurality of conductive non-magnetic intermediate layers formed between the free magnetization layer and the fixed magnetization layer. An insulating layer and a magnetic layer including magnetic atoms are provided between any two of the non-magnetic intermediate layers.
    Type: Application
    Filed: January 25, 2005
    Publication date: July 14, 2005
    Inventors: Keiichi Nagasaka, Yoshihiko Seyama, Hirotaka Oshima, Yutaka Shimizu, Atsushi Tanaka
  • Patent number: 6801413
    Abstract: A magnetic sensor having such a structure that a hard layer for controlling the magnetic domain formed of a conductive hard magnetic material, and a magnetic sensor layer, are at least partially in direct contact with each other, and current flows in the direction wherein at least a main component of current is perpendicular to the surface of the magnetic sensor layer. The current flowing in the magnetic sensor layer and the hard layer is controlled by changing the resistivity of the hard layer. The magnetic sensor is used as a magnetic read head in a magnetic recording apparatus such as magnetic disk apparatus.
    Type: Grant
    Filed: March 26, 2002
    Date of Patent: October 5, 2004
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Keiichi Nagasaka, Yutaka Shimizu, Atsushi Tanaka
  • Patent number: 6781799
    Abstract: A current perpendicular-to-the-plane (CPP) structure spin valve magnetoresistive (MR) transducer includes an insulating layer. A pinned or free ferromagnetic layer serves to space or isolate the insulating layer from a non-magnetic spacer layer interposed between the pinned and free ferromagnetic layers. The sensing current is allowed to penetrate through the insulating layer. Fine pin-holes generally formed in the insulating layer are supposed to enable migration of electrons through the insulating layer. Similar to the situation in which the sensing current is allowed to flow through a reduced sectional area, a larger variation can be obtained in response to the inversion of the magnetization in the free ferromagnetic layer. The spin valve MR transducer is expected to greatly contribute to realization of a still higher recording density.
    Type: Grant
    Filed: March 29, 2001
    Date of Patent: August 24, 2004
    Assignee: Fujitsu Limited
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu
  • Publication number: 20030128481
    Abstract: A current-perpendicular-to-the-plane (CPP) structure magnetoresistive element includes a spin valve film. A boundary is defined between electrically-conductive layers included in a non-magnetic intermediate layer in the spin valve film. A magnetic metallic material and an insulating material exist on the boundary. The insulating material serves to reduce the sectional area of the path for the sensing electric current. The CPP structure magnetoresistive element realizes a larger variation in the electric resistance in response to the rotation of the magnetization in the free magnetic layer. A sensing electric current of a smaller level is still employed to obtain a sufficient variation in the voltage. Accordingly, the CPP structure magnetoresistive element greatly contributes to a further improvement in the recording density and reduction in the electric consumption.
    Type: Application
    Filed: December 19, 2002
    Publication date: July 10, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Yoshihiko Seyama, Keiichi Nagasaka, Hirotaka Oshima, Yutaka Shimizu, Atsushi Tanaka
  • Publication number: 20030123200
    Abstract: A magnetoresistive element that detects a change of magnetoresistance by giving a sense current in the thickness direction of a magnetoresistive effect film including at least a base layer, a free layer, a non-magnetic layer, a pinned layer, a pinning layer, and a protection layer, includes a granular structure layer that includes conductive particles and an insulating matrix material in the form of a thin film containing the conductive particles in a dispersed state and having a smaller thickness than the particle diameter of the conductive particles, the granular structure layer being interposed between at least two adjacent layers among the base layer, the free layer, the non-magnetic layer, the pinned layer, the pinning layer, and the protection layer.
    Type: Application
    Filed: October 16, 2002
    Publication date: July 3, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Keiichi Nagasaka, Yoshihiko Seyama, Takahiko Sugawara, Yutaka Shimizu, Atsushi Tanaka
  • Publication number: 20030090844
    Abstract: A magnetoresistive device includes a laminated film, and a mechanism for applying sense current in a direction of lamination in the laminated film, wherein the laminated film includes a first ferromagnetic layer having a substantially fixed direction of magnetization, a second ferromagnetic layer having a freely variable direction of magnetization according to an external magnetic field, the second ferromagnetic layer including a non-magnetic metal layer, and two or more ferromagnetic metal layers separated from each other by the non-magnetic metal layer in the direction of lamination, and a non-magnetic intermediate layer that separates the first and second ferromagnetic layer from each other.
    Type: Application
    Filed: April 3, 2002
    Publication date: May 15, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Yutaka Shimizu, Hirotaka Oshima, Keiichi Nagasaka, Yoshihiko Seyama, Atsushi Tanaka
  • Publication number: 20030039083
    Abstract: A magnetic sensor having such a structure that a hard layer for controlling the magnetic domain formed of a conductive hard magnetic material, and a magnetic sensor layer, are at least partially in direct contact with each other, and current flows in the direction wherein at least a main component of current is perpendicular to the surface of the magnetic sensor layer. The current flowing in the magnetic sensor layer and the hard layer is controlled by changing the resistivity of the hard layer. The magnetic sensor is used as a magnetic read head in a magnetic recording apparatus such as magnetic disk apparatus.
    Type: Application
    Filed: March 26, 2002
    Publication date: February 27, 2003
    Applicant: FUJITSU LIMITED
    Inventors: Yoshihiko Seyama, Keiichi Nagasaka, Yutaka Shimizu, Atsushi Tanaka
  • Patent number: 6441611
    Abstract: A magnetic sensor utilizing a giant magnetoresistance (GMR) effect, wherein an insulation layer with a contact hole is formed on a lower terminal layer, a GMR layer is formed thereover on the region including the entire contact hole and at least the surrounding insulation layer, and an upper terminal layer is formed thereover. The sensor offers several advantages in that it is easy to manufacture and is compact, and has a high degree of resistance change.
    Type: Grant
    Filed: December 27, 2000
    Date of Patent: August 27, 2002
    Assignee: Fujitsu Limited
    Inventor: Yoshihiko Seyama
  • Publication number: 20020097538
    Abstract: A current perpendicular-to-the-plane (CPP) structure spin valve magnetoresistive (MR) transducer includes an insulating layer. A pinned or free ferromagnetic layer serves to space or isolate the insulating layer from a non-magnetic spacer layer interposed between the pinned and free ferromagnetic layers. The sensing current is allowed to penetrate through the insulating layer. Fine pin-holes generally formed in the insulating layer are supposed to enable migration of electrons through the insulating layer. Similar to the situation in which the sensing current is allowed to flow through a reduced sectional area, a larger variation can be obtained in response to the inversion of the magnetization in the free ferromagnetic layer. The spin valve MR transducer is expected to greatly contribute to realization of a still higher recording density.
    Type: Application
    Filed: March 29, 2001
    Publication date: July 25, 2002
    Applicant: FUJITSU LIMITED
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu
  • Publication number: 20020034055
    Abstract: Disclosed herein is a spin valve magnetoresistive sensor including a first conductor layer, a free ferromagnetic layer provided on the first conductor layer, a nonmagnetic intermediate layer provided on the free ferromagnetic layer, a pinned ferromagnetic layer provided on the nonmagnetic intermediate layer, an antiferromagnetic layer provided on the pinned ferromagnetic layer, and a second conductor layer provided on the antiferromagnetic layer. At least one of the free ferromagnetic layer and the pinned ferromagnetic layer has a thickness larger than that providing a maximum resistance change rate or resistance change amount in the case of passing a current in an in-plane direction of the at least one layer. That is, the thickness of at least one of the free ferromagnetic layer and the pinned ferromagnetic layer falls in the range of 3 nm to 12 nm.
    Type: Application
    Filed: March 28, 2001
    Publication date: March 21, 2002
    Applicant: FUJITSU LIMITED
    Inventors: Yoshihiko Seyama, Atsushi Tanaka, Keiichi Nagasaka, Yutaka Shimizu, Shin Eguchi, Hitoshi Kanai, Reiko Kondo, Hitoshi Kishi, Junya Ikeda
  • Publication number: 20010049412
    Abstract: A raw material for injection molding comprising a metal powder or a ceramic powder, and a binder containing at least two types of resins, obtained by coating or encapsulating the metal powder or ceramic powder particles with a resin insoluble in a predetermined solvent and having a high softening temperature, and subsequently kneading the resultant powder and a resin soluble in the solvent and having a low softening temperature.
    Type: Application
    Filed: July 13, 2001
    Publication date: December 6, 2001
    Inventors: Yoshihiko Seyama, Yutaka Shimizu, Shinya Iijima