Patents by Inventor Takahiro Ibusuki
Takahiro Ibusuki 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).
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Magnetoresistive element including an amorphous reference layer, a crystal layer, and a pinned layer
Patent number: 8081404Abstract: A magnetoresistive element includes: a free layer made of a ferromagnetic material, the free layer configured to change the direction of magnetization under the influence of an external magnetic field; an insulating layer overlaid on the free layer, the insulating layer made of an insulating material; an amorphous reference layer overlaid on the insulating layer, the amorphous reference layer made of a ferromagnetic material, the amorphous reference layer configured to fix the magnetization in a predetermined direction; a crystal layer overlaid on the amorphous reference layer, the crystal layer containing crystal grains; a non-magnetic layer overlaid on the crystal layer, the non-magnetic layer containing crystal grains having grown from the crystal grains in the crystal layer; and a pinned layer overlaid on the non-magnetic layer, the pinned layer configured to fix the magnetization in a predetermined direction.Type: GrantFiled: August 27, 2009Date of Patent: December 20, 2011Assignee: Fujitsu LimitedInventors: Takahiro Ibusuki, Shinjiro Umehara, Masashige Sato -
Patent number: 8072714Abstract: A barrier layer is disposed over a pinned layer made of ferromagnetic material having a fixed magnetization direction, the barrier layer having a thickness allowing electrons to transmit therethrough by a tunneling phenomenon. A first free layer is disposed over the barrier layer, the first free layer being made of amorphous or fine crystalline soft magnetic material which changes a magnetization direction under an external magnetic field. A second free layer is disposed over the first free layer, the second free layer being made of crystalline soft magnetic material which changes a magnetization direction under an external magnetic field and being exchange-coupled to the first free layer. A tunneling magnetoresistance device is provided which has good magnetic characteristics and can suppress a tunnel resistance change rate from being lowered.Type: GrantFiled: March 11, 2011Date of Patent: December 6, 2011Assignee: Fujitsu LimitedInventors: Masashige Sato, Shinjiro Umehara, Takahiro Ibusuki
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Publication number: 20110164448Abstract: A barrier layer is disposed over a pinned layer made of ferromagnetic material having a fixed magnetization direction, the barrier layer having a thickness allowing electrons to transmit therethrough by a tunneling phenomenon. A first free layer is disposed over the barrier layer, the first free layer being made of amorphous or fine crystalline soft magnetic material which changes a magnetization direction under an external magnetic field. A second free layer is disposed over the first free layer, the second free layer being made of crystalline soft magnetic material which changes a magnetization direction under an external magnetic field and being exchange-coupled to the first free layer. A tunneling magnetoresistance device is provided which has good magnetic characteristics and can suppress a tunnel resistance change rate from being lowered.Type: ApplicationFiled: March 11, 2011Publication date: July 7, 2011Applicant: Fujitsu LimitedInventors: Masashige Sato, Shinjiro Umehara, Takahiro Ibusuki
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Publication number: 20100284103Abstract: A magnetoresistive effect device includes an underlayer, an antiferromagnetic layer, a first ferromagnetic layer, a nonmagnetic layer, and a second ferromagnetic layer which are multilayered in this order on a substrate. The underlayer is formed of a metal nitride, and the antiferromagnetic layer is formed of an antiferromagnetic material including Ir and Mn.Type: ApplicationFiled: July 23, 2010Publication date: November 11, 2010Applicant: FUJITSU LIMITEDInventors: Takahiro Ibusuki, Masashige Sato, Shinjiro Umehara
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Publication number: 20100159283Abstract: A magnetic storage medium includes a substrate, a first magnetic layer film that is deposited on the substrate, and a second magnetic layer film that is a cap layer of the first magnetic layer film. The first magnetic layer film contains a high magnetic anisotropic material and a low-temperature diffusion material which is added to the high magnetic anisotropic material, the low-temperature diffusion material starting diffusion by thermal treatment at a lower temperature than that of the high magnetic anisotropic material. The second magnetic layer film includes a material for promoting diffusion of the low-temperature diffusion material.Type: ApplicationFiled: October 20, 2009Publication date: June 24, 2010Applicant: SHOWA DENKO K.K.Inventors: Takahiro IBUSUKI, Masashige SATO
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Publication number: 20100053824Abstract: A magnetoresistive element includes: a free layer made of a ferromagnetic material, the free layer configured to change the direction of magnetization under the influence of an external magnetic field; an insulating layer overlaid on the free layer, the insulating layer made of an insulating material; an amorphous reference layer overlaid on the insulating layer, the amorphous reference layer made of a ferromagnetic material, the amorphous reference layer configured to fix the magnetization in a predetermined direction; a crystal layer overlaid on the amorphous reference layer, the crystal layer containing crystal grains; a non-magnetic layer overlaid on the crystal layer, the non-magnetic layer containing crystal grains having grown from the crystal grains in the crystal layer; and a pinned layer overlaid on the non-magnetic layer, the pinned layer configured to fix the magnetization in a predetermined direction.Type: ApplicationFiled: August 27, 2009Publication date: March 4, 2010Applicant: FUJITSU LIMITEDInventors: Takahiro Ibusuki, Shinjiro Umehara, Masashige Sato
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Publication number: 20090244790Abstract: An magnetoresistive element includes: an underlayer made of a nitride; a pinning layer made of an antiferromagnetic layer overlaid on the underlayer, the pinning layer having the close-packed surface in the (111) surface of crystal, the pinning layer setting the (002) surface of crystal in parallel with the surface of the underlayer; a reference layer overlaid on the pinning layer, the reference layer having the magnetization fixed in a predetermined direction based on the exchange coupling with the pinning layer; a nonmagnetic layer overlaid on the reference layer, the nonmagnetic layer made of a nonmagnetic material; and a free layer overlaid on the nonmagnetic layer, the free layer made of a ferromagnetic material, the free layer enabling a change in the direction of the magnetization under the influence of an external magnetic field.Type: ApplicationFiled: March 23, 2009Publication date: October 1, 2009Applicant: FUJITSU LIMITEDInventors: Takahiro Ibusuki, Masashige Sato, Shinjiro Umehara
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Publication number: 20090141410Abstract: An electrically-conductive or insulating non-magnetic intermediate layer is inserted between a free magnetic layer and a pinned magnetic layer in a current-perpendicular-to-the-plane (CPP) structure magnetoresistive element. At least one of the free magnetic layer and the pinned magnetic layer is made of a nitrided magnetic metal alloy. This nitrided magnetic layers allows the CPP structure magnetoresistive element to enjoy an increased magnetoresistance change (?RA). In addition, the saturation magnetic flux density (Bs) decreases in a nitrided magnetic metal alloy. The inversion of magnetization is thus easily caused in the low Bs magnetic layer. The detection sensitivity of the CPP structure magnetoresistive element is improved. The CPP structure magnetoresistive element is thus allowed to detect magnetic bit data with higher accuracy.Type: ApplicationFiled: September 12, 2008Publication date: June 4, 2009Applicant: FUJITSU LIMITEDInventors: Arata Jogo, Takahiro Ibusuki, Yutaka Shimizu
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Publication number: 20090097170Abstract: A ferromagnetic tunnel junction element is a magnetoresistance effect element wherein an electric resistance varies in accordance with a magnetic field applied. The ferromagnetic tunnel junction element includes a pinned layer wherein at least a part of a magnetization direction is held, and an insulation layer formed on the pinned layer, creating an energy barrier that electrons can flow through by a tunnel effect. A first free layer made of a first ferromagnetic material containing boron atoms, is formed on the insulation layer. In the first free layer, a direction of the magnetization switches under an influence of an external magnetic field. A second free layer made of a first ferromagnetic material containing boron atoms, is formed on the first free layer. The direction of magnetization of the second free layer switches under the influence of the external magnetic field, exchanging and coupling with the first free layer.Type: ApplicationFiled: September 2, 2008Publication date: April 16, 2009Applicant: FUJITSU LIMITEDInventors: Masashige Sato, Shinjiro Umehara, Takahiro Ibusuki
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Publication number: 20080232003Abstract: An underlying layer (2) made of NiFeN is disposed over the principal surface of a substrate. A pinning layer (3) made of antiferromagnetic material containing Ir and Mn is disposed on the underlying layer. A reference layer (4c) made of ferromagnetic material whose magnetization direction is fixed through exchange-coupling with the pinning layer directly or via another ferromagnetic material layer, is disposed over the pinning layer. A nonmagnetic layer (7) made of nonmagnetic material is disposed over the reference layer. A free layer (8) made of ferromagnetic material whose magnetization direction changes in dependence upon an external magnetic field, is disposed over the nonmagnetic layer.Type: ApplicationFiled: March 3, 2008Publication date: September 25, 2008Applicant: FUJITSU LIMITEDInventors: Takahiro IBUSUKI, Masashige SATO, Shinjiro UMEHARA
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Patent number: 7428130Abstract: A CPP-type magnetoresistive element including a fixed magnetization layer, a non-magnetic metal layer, and a free magnetization layer that are stacked, and a diffusion prevention layer is disclosed. The free magnetization layer includes CoMnAl. The diffusion prevention layer is provided between the non-magnetic metal layer and the free magnetization layer so as to prevent Mn included in the free magnetization layer from diffusing into the non-magnetic metal layer. CoMnAl has a composition within the area formed by connecting Point A (44, 23, 33), Point B (48, 25, 27), Point C (60, 20, 20), Point D (65, 15, 20), Point E (65, 10, 25), Point F (60, 10, 30), and Point A with straight lines in this order in a ternary composition diagram where coordinates of the composition are expressed as (Co content, Mn content, Al content) with each of the Co, Mn, and Al contents being expressed in atomic percentage.Type: GrantFiled: April 25, 2006Date of Patent: September 23, 2008Assignee: Fujitsu LimitedInventors: Arata Jogo, Hirotaka Oshima, Takahiro Ibusuki, Yutaka Shimizu, Takuya Uzumaki
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Publication number: 20080204946Abstract: A magnetoresistance effect element having a free magnetic layer is provided. The free magnetic layer is formed in a laminate including a fixed magnetization layer having a fixed magnetization direction, a non-magnetic layer formed on the fixed magnetization layer, a first ferromagnetic layer, a non-magnetic metallic layer formed on the first ferromagnetic layer, and a second ferromagnetic layer formed on the non-magnetic metallic layer. The free magnetic layer includes magnetic recording regions, and in each region, the first ferromagnetic layer and the second ferromagnetic layer are coupled such that their magnetization directions are anti-parallel with each other, and one of the magnetic recording regions is opposite to the fixed magnetization layer with the non-magnetic layer therebetween.Type: ApplicationFiled: February 26, 2008Publication date: August 28, 2008Applicant: FUJITSU LIMITEDInventors: Takao OCHIAI, Hiroshi ASHIDA, Takahiro IBUSUKI, Yutaka SHIMIZU
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Publication number: 20080112093Abstract: A barrier layer is disposed over a pinned layer made of ferromagnetic material having a fixed magnetization direction, the barrier layer having a thickness allowing electrons to transmit therethrough by a tunneling phenomenon. A first free layer is disposed over the barrier layer, the first free layer being made of amorphous or fine crystalline soft magnetic material which changes a magnetization direction under an external magnetic field. A second free layer is disposed over the first free layer, the second free layer being made of crystalline soft magnetic material which changes a magnetization direction under an external magnetic field and being exchange-coupled to the first free layer. A tunneling magnetoresistance device is provided which has good magnetic characteristics and can suppress a tunnel resistance change rate from being lowered.Type: ApplicationFiled: September 6, 2007Publication date: May 15, 2008Applicant: Fujitsu LimitedInventors: Masashige Sato, Shinjiro Umehara, Takahiro Ibusuki
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Publication number: 20080080102Abstract: A TMR element is provided which has a large MR ratio. The TMR element has a tunnel barrier layer formed between a magnetization fixed layer and a magnetization free layer, and a cap layer disposed on the magnetization free layer. The tunnel barrier layer is formed of an MgO film. The magnetization free layer is formed of a CoFeB film. The cap layer is formed by forming a Ti film immediately above the CoFeB film such that the Ti film is in contact with the CoFeB film. This makes it possible to largely enhance the MR ratio of the TMR element. Further, by using the TMR element for a magnetic head and an MRAM, it is possible to improve the performance of magnetic heads and MRAMs.Type: ApplicationFiled: September 26, 2007Publication date: April 3, 2008Applicant: FUJITSU LIMITEDInventors: Takahiro Ibusuki, Masashige Sato, Shinjiro Umehara
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Publication number: 20080070063Abstract: An exchange coupling film of the present invention has a sandwich structure with a non-magnetic layer of a Ru—Rh alloy between two ferromagnetic layers. In a case of applying the exchange coupling film of the present invention to a magnetic head (reading element), the non-magnetic layer is set to have, for example, a thickness of 0.4 nm to 0.5 nm, and a Rh content of 5 at % to 40 at %. In a case of applying the exchange coupling film of the present invention to a magnetic recording medium, the non-magnetic layer is set to have, for example, a thickness of 0.4 nm to 0.6 nm, and a Rh content of 5 at % to 70 at %. In a case of applying the exchange coupling film of the present invention to an MRAM, the non-magnetic layer is set to have, for example, a thickness of 0.3 nm to 0.7 nm, and a Rh content of 5 at % to 40 at %.Type: ApplicationFiled: September 14, 2007Publication date: March 20, 2008Applicant: FUJITSU LIMITEDInventors: Takahiro Ibusuki, Masashige Sato
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Publication number: 20070268632Abstract: A CPP-type magnetoresistive element including a fixed magnetization layer, a non-magnetic metal layer, and a free magnetization layer that are stacked, and a diffusion prevention layer is disclosed. The free magnetization layer includes CoMnAl. The diffusion prevention layer is provided between the non-magnetic metal layer and the free magnetization layer so as to prevent Mn included in the free magnetization layer from diffusing into the non-magnetic metal layer. CoMnAl has a composition within the area formed by connecting Point A (44, 23, 33), Point B (48, 25, 27), Point C (60, 20, 20), Point D (65, 15, 20), Point E (65, 10, 25), Point F (60, 10, 30), and Point A with straight lines in this order in a ternary composition diagram where coordinates of the composition are expressed as (Co content, Mn content, Al content) with each of the Co, Mn, and Al contents being expressed in atomic percentage.Type: ApplicationFiled: April 25, 2006Publication date: November 22, 2007Applicant: FUJITSU LIMITEDInventors: Arata Jogo, Hirotaka Oshima, Takahiro Ibusuki, Yutaka Shimizu, Takuya Uzumaki