Patents by Inventor Tadashi Kai
Tadashi Kai 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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Publication number: 20130001714Abstract: According to one embodiment, a magnetoresistive element includes a storage layer having a perpendicular and variable magnetization, a reference layer having a perpendicular and invariable magnetization, a shift adjustment layer having a perpendicular and invariable magnetization in a direction opposite to a magnetization of the reference layer, a first nonmagnetic layer between the storage layer and the reference layer, and a second nonmagnetic layer between the reference layer and the shift adjustment layer. A switching magnetic field of the reference layer is equal to or smaller than a switching magnetic field of the storage layer, and a magnetic relaxation constant of the reference layer is larger than a magnetic relaxation constant of the storage layer.Type: ApplicationFiled: March 19, 2012Publication date: January 3, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Katsuya Nishiyama, Hisanori Aikawa, Tadashi Kai, Toshihiko Nagase, Koji Ueda, Hiroaki Yoda
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Patent number: 8305801Abstract: A magnetoresistive element according to an embodiment includes: a first ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a second ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a nonmagnetic layer placed between the first ferromagnetic layer and the second ferromagnetic layer; a first interfacial magnetic layer placed between the first ferromagnetic layer and the nonmagnetic layer; and a second interfacial magnetic layer placed between the second ferromagnetic layer and the nonmagnetic layer. The first interfacial magnetic layer includes a first interfacial magnetic film, a second interfacial magnetic film placed between the first interfacial magnetic film and the nonmagnetic layer and having a different composition from that of the first interfacial magnetic film, and a first nonmagnetic film placed between the first interfacial magnetic film and the second interfacial magnetic film.Type: GrantFiled: March 8, 2011Date of Patent: November 6, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Tadaomi Daibou, Eiji Kitagawa, Yutaka Hashimoto, Masaru Tokou, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Makoto Nagamine, Tadashi Kai, Hiroaki Yoda
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Publication number: 20120268844Abstract: An example magnetic writing head includes a main magnetic pole, a coil to generate an ampere magnetic field to magnetize the main magnetic pole to cause the magnetized main magnetic pole to generate a magnetic field, and a laminated body. The laminated body includes a first magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole and a second magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole.Type: ApplicationFiled: July 3, 2012Publication date: October 25, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Kenichiro Yamada, Hitoshi Iwasaki, Junichi Akiyama, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Mariko Shimizu, Shuichi Murakami, Tadashi Kai
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Patent number: 8295009Abstract: An example magnetic recording head includes: a main magnetic pole; a laminated body; and a pair of electrodes. The laminated body includes a first magnetic layer having a coercivity lower than magnetic field applied by the main magnetic pole, a second magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole, and an intermediate layer provided between the first magnetic layer and the second magnetic layer. The pair of electrodes is operable to pass a current through the laminated body.Type: GrantFiled: August 19, 2011Date of Patent: October 23, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Kenichiro Yamada, Hitoshi Iwasaki, Junichi Akiyama, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Mariko Shimizu, Shuichi Murakami, Tadashi Kai
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Patent number: 8279663Abstract: A magnetoresistance effect element includes: a first ferromagnetic layer having invariable magnetization perpendicular to a film plane; a second ferromagnetic layer having variable magnetization perpendicular to the film plane; a first nonmagnetic layer interposed between the first ferromagnetic layer and the second ferromagnetic layer; a third ferromagnetic layer provided on an opposite side of the second ferromagnetic layer from the first nonmagnetic layer, and having variable magnetization parallel to the film plane; and a second nonmagnetic layer interposed between the second and third ferromagnetic layers.Type: GrantFiled: July 18, 2011Date of Patent: October 2, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Masahiko Nakayama, Tadashi Kai, Sumio Ikegawa, Hiroaki Yoda, Tatsuya Kishi
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Publication number: 20120241881Abstract: A magnetoresistive element according to an embodiment includes: a base layer; a first magnetic layer formed on the base layer, and including a first magnetic film having an axis of easy magnetization in a direction perpendicular to a film plane, the first magnetic film including MnxGa100-x (45?x<64 atomic %); a first nonmagnetic layer formed on the first magnetic layer; and a second magnetic layer formed on the first nonmagnetic layer, and including a second magnetic film having an axis of easy magnetization in a direction perpendicular to a film plane, the second magnetic film including MnyGa100-y (45?y<64 atomic %). The first and second magnetic layers include different Mn composition rates from each other, a magnetization direction of the first magnetic layer is changeable by a current flowing between the first magnetic layer and the second magnetic layer via the first nonmagnetic layer.Type: ApplicationFiled: December 2, 2011Publication date: September 27, 2012Applicants: Tohoku University, KABUSHIKI KAISHA TOSHIBAInventors: Tadaomi DAIBOU, Junichi Ito, Tadashi Kai, Minoru Amano, Hiroaki Yoda, Terunobu Miyazaki, Shigemi Mizukami, Koji Ando, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Akio Fukushima, Taro Nagahama, Takahide Kubota
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Publication number: 20120241884Abstract: According to one embodiment, a magnetic memory includes a magnetoresistive element. The magnetoresistive element includes a reference layer having an invariable magnetization direction, a storage layer having a variable magnetization direction, and a spacer layer provided between the reference layer and the storage layer. The storage layer has a multilayered structure including first and second magnetic layers, the second magnetic layer is provided between the first magnetic layer and the spacer layer and has a magnetic anisotropy energy lower than that of the first magnetic layer, and an exchange coupling constant Jex between the first magnetic layer and the second magnetic layer is not more than 5 erg/cm2.Type: ApplicationFiled: March 28, 2012Publication date: September 27, 2012Inventors: Hisanori AIKAWA, Tadashi Kai, Masahiko Nakayama, Sumio Ikegawa, Naoharu Shimomura, Eiji Kitagawa, Tatsuya Kishi, Jyunichi Ozeki, Hiroaki Yoda, Satoshi Yanagi
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Patent number: 8238060Abstract: A magnetic recording head includes: a main magnetic pole; a laminated body; and a pair of electrodes. The laminated body includes a first magnetic layer having a coercivity lower than magnetic field applied by the main magnetic pole, a second magnetic layer having a coercivity lower than the magnetic field applied by the main magnetic pole, and an intermediate layer provided between the first magnetic layer and the second magnetic layer. The pair of electrodes are operable to pass a current through the laminated body.Type: GrantFiled: May 14, 2010Date of Patent: August 7, 2012Inventors: Kenichiro Yamada, Hitoshi Iwasaki, Junichi Akiyama, Masayuki Takagishi, Tomomi Funayama, Masahiro Takashita, Mariko Shimizu, Shuichi Murakami, Tadashi Kai
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Patent number: 8223533Abstract: A magnetic memory includes a magnetoresistive effect device comprising: a first ferromagnetic layer that has magnetic anisotropy in a direction perpendicular to a film plane thereof; a first nonmagnetic layer that is provided on the first ferromagnetic layer; a first reference layer that is provided on the first nonmagnetic layer, has magnetic anisotropy in a direction perpendicular to a film plane thereof, has magnetization antiparallel to a magnetization direction of the first ferromagnetic layer, and has a film thickness that is 1/5.2 to 1/1.Type: GrantFiled: September 10, 2009Date of Patent: July 17, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Jyunichi Ozeki, Naoharu Shimomura, Sumio Ikegawa, Tadashi Kai, Masahiko Nakayama, Hisanori Aikawa, Tatsuya Kishi, Hiroaki Yoda, Eiji Kitagawa, Masatoshi Yoshikawa
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Publication number: 20120163070Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer with a perpendicular and variable magnetization, a second magnetic layer with a perpendicular and invariable magnetization, and a first nonmagnetic layer between the first and second magnetic layer. The first magnetic layer has a laminated structure of first and second ferromagnetic materials. A magnetization direction of the first magnetic layer is changed by a current which pass through the first magnetic layer, the first nonmagnetic layer and the second magnetic layer. A perpendicular magnetic anisotropy of the second ferromagnetic material is smaller than that of the first ferromagnetic material. A film thickness of the first ferromagnetic material is thinner than that of the second ferromagnetic material.Type: ApplicationFiled: February 28, 2012Publication date: June 28, 2012Inventors: Toshihiko Nagase, Tadashi Kai, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Masahiko Nakayama, Makoto Nagamine, Shigeto Fukatsu, Masatoshi Yoshikawa, Hiroaki Yoda
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Patent number: 8208292Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer with a variable magnetization and an easy-axis in a perpendicular direction to a film surface, a second magnetic layer with an invariable magnetization and an easy-axis in the perpendicular direction, and a first nonmagnetic layer between the first and second magnetic layers. The first magnetic layer comprises a ferromagnetic material including an alloy in which Co and Pd, or Co and Pt are alternately laminated on an atomically close-packed plane thereof. The first magnetic layer has C-axis directing the perpendicular direction. And a magnetization direction of the first magnetic layer is changed by a current flowing through the first magnetic layer, the first nonmagnetic layer and the second magnetic layer.Type: GrantFiled: January 3, 2012Date of Patent: June 26, 2012Assignees: Kabushiki Kaisha Toshiba, National Institute of Advanced Industrial Science and TechnologyInventors: Tadashi Kai, Katsuya Nishiyama, Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Masahiko Nakayama, Naoharu Shimomura, Hiroaki Yoda, Kei Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
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Patent number: 8169817Abstract: A magnetoresistive device includes: a magnetic recording layer including a first magnetic layer having perpendicular magnetic anisotropy, and a second magnetic layer having in-plane magnetic anisotropy and being exchange-coupled to the first magnetic layer, Curie temperature of the second magnetic layer being lower than Curie temperature of the first magnetic layer, and the magnetic recording layer having a magnetization direction perpendicular to a film plane; a magnetic reference layer having a magnetization direction which is perpendicular to a film plane and is invariable; and a nonmagnetic layer provided between the magnetic recording layer and the magnetic reference layer. The magnetization direction of the magnetic recording layer is changeable by spin-polarized electrons caused by flowing current between the magnetic recording layer and the magnetic reference layer in a direction perpendicular to the film plane.Type: GrantFiled: March 2, 2010Date of Patent: May 1, 2012Assignee: Kabushiki Kaisha ToshibaInventors: Masahiko Nakayama, Hiroaki Yoda, Tadashi Kai, Hisanori Aikawa, Katsuya Nishiyama, Jyunichi Ozeki
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Publication number: 20120099369Abstract: According to one embodiment, a magnetoresistive element includes a first magnetic layer with a variable magnetization and an easy-axis in a perpendicular direction to a film surface, a second magnetic layer with an invariable magnetization and an easy-axis in the perpendicular direction, and a first nonmagnetic layer between the first and second magnetic layers. The first magnetic layer comprises a ferromagnetic material including an alloy in which Co and Pd, or Co and Pt are alternately laminated on an atomically close-packed plane thereof. The first magnetic layer has C-axis directing the perpendicular direction. And a magnetization direction of the first magnetic layer is changed by a current flowing through the first magnetic layer, the first nonmagnetic layer and the second magnetic layer.Type: ApplicationFiled: January 3, 2012Publication date: April 26, 2012Inventors: Tadashi KAI, Katsuya Nishiyama, Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Masahiko Nakayama, Naoharu Shimomura, Hiroaki Yoda, Kei Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
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Publication number: 20120088125Abstract: A magnetoresistive element according to an embodiment includes: a base layer; a first magnetic layer formed on the base layer and having a changeable magnetization direction with an easy axis of magnetization in a direction perpendicular to a film plane; a first nonmagnetic layer formed on the first magnetic layer; and a second magnetic layer formed on the first nonmagnetic layer and having a fixed magnetization layer with an easy axis of magnetization in a direction perpendicular to the film plane. The first magnetic layer includes a ferrimagnetic layer having a DO22 structure or an L10 structure, the ferrimagnetic layer has a c-axis oriented in a direction perpendicular to the film plane, and the magnetization direction of the first magnetic layer is changeable by a current flowing through the first magnetic layer, the first nonmagnetic layer, and the second magnetic layer.Type: ApplicationFiled: September 19, 2011Publication date: April 12, 2012Applicants: NATIONAL UNIVERSITY CORPORATION TOHOKU UNIVERSITY, KABUSHIKI KAISHA TOSHIBAInventors: Katsuya NISHIYAMA, Wu Feng, Chunlan Feng, Shigemi Mizukami, Terunobu Miyazaki, Hiroaki Yoda, Tadashi Kai, Tatsuya Kishi, Daisuke Watanabe, Mikihiko Oogane, Yasuo Ando, Masatoshi Yoshikawa, Toshihiko Nagase, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine
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Publication number: 20120070695Abstract: According to one embodiment, a magnetoresistive element includes a recording layer having a variable magnetization direction, a reference layer having an invariable magnetization direction, an intermediate layer provided between the recording layer and the reference layer, and a first buffer layer provided on a surface of the recording layer, which is opposite to a surface of the recording layer where the intermediate layer is provided. The recording layer comprises a first magnetic layer which is provided in a side of the intermediate layer and contains CoFe as a main component, and a second magnetic layer which is provided in a side of the first buffer layer and contains CoFe as a main component, a concentration of Fe in the first magnetic layer being higher than a concentration of Fe in the second magnetic layer. The first buffer layer comprises a nitrogen compound.Type: ApplicationFiled: September 16, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Eiji Kitagawa, Tadaomi Daibou, Tadashi Kai, Toshihiko Nagase, Kenji Noma, Hiroaki Yoda
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Publication number: 20120069640Abstract: A magnetoresistive element according to an embodiment includes: a first and second magnetic layers having an easy axis of magnetization in a direction perpendicular to a film plane; and a first nonmagnetic layer interposed between the first and second magnetic layers, at least one of the first and second magnetic layers including a structure formed by stacking a first and second magnetic films, the second magnetic film being located closer to the first nonmagnetic layer, the second magnetic film including a structure formed by repeating stacking of a magnetic material layer and a nonmagnetic material layer at least twice, the nonmagnetic material layers of the second magnetic film containing at least one element selected from the group consisting of Ta, W, Hf, Zr, Nb, Mo, Ti, V, and Cr, one of the first and second magnetic layers having a magnetization direction that is changed by applying a current.Type: ApplicationFiled: September 14, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Toshihiko Nagase, Tadashi Kai, Makoto Nagamine, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
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Publication number: 20120069642Abstract: According to one embodiment, a magnetoresistive element includes an electrode layer, a first magnetic layer, a second magnetic layer and a nonmagnetic layer. The electrode layer includes a metal layer including at least one of Mo, Nb, and W. The first magnetic layer is disposed on the metal layer to be in contact with the metal layer and has a magnetization easy axis in a direction perpendicular to a film plane and is variable in magnetization direction. The second magnetic layer is disposed on the first magnetic layer and has a magnetization easy axis in the direction perpendicular to the film plane and is invariable in magnetization direction. The nonmagnetic layer is provided between the first and second magnetic layers. The magnetization direction of the first magnetic layer is varied by a current that runs through the first magnetic layer, the nonmagnetic layer, and the second magnetic layer.Type: ApplicationFiled: September 19, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Koji Ueda, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Eiji Kitagawa, Tadaomi Daibou, Makoto Nagamine, Hiroaki Yoda
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Publication number: 20120068139Abstract: A magnetoresistive element according to an embodiment includes: a first ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a second ferromagnetic layer having an axis of easy magnetization in a direction perpendicular to a film plane; a nonmagnetic layer placed between the first ferromagnetic layer and the second ferromagnetic layer; a first interfacial magnetic layer placed between the first ferromagnetic layer and the nonmagnetic layer; and a second interfacial magnetic layer placed between the second ferromagnetic layer and the nonmagnetic layer. The first interfacial magnetic layer includes a first interfacial magnetic film, a second interfacial magnetic film placed between the first interfacial magnetic film and the nonmagnetic layer and having a different composition from that of the first interfacial magnetic film, and a first nonmagnetic film placed between the first interfacial magnetic film and the second interfacial magnetic film.Type: ApplicationFiled: March 8, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Tadaomi Daibou, Eiji Kitagawa, Yutaka Hashimoto, Masaru Tokou, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Makoto Nagamine, Tadashi Kai, Hiroaki Yoda
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Publication number: 20120068284Abstract: According to one embodiment, a magnetoresistive effect element includes a recording layer including ferromagnetic material with perpendicular magnetic anisotropy to a film surface and a variable orientation of magnetization, a reference layer including ferromagnetic material with perpendicular magnetic anisotropy to a film surface and an invariable orientation of magnetization, a nonmagnetic layer between the recording layer and the reference layer, a first underlayer on a side of the recoding layer opposite to a side on which the nonmagnetic layer is provided, and a second underlayer between the recording layer and the first underlayer. The second underlayer is a Pd film including a concentration of 3×1015 atms/cm2.Type: ApplicationFiled: September 15, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Eiji Kitagawa, Tadaomi Daibou, Tadashi Kai, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda
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Publication number: 20120068285Abstract: According to one embodiment, a magnetoresistive effect element includes a first magnetic layer including perpendicular anisotropy to a film surface and an invariable magnetization direction, the first magnetic layer having a magnetic film including an element selected from a first group including Tb, Gd, and Dy and an element selected from a second group including Co and Fe, a second magnetic layer including perpendicular magnetic anisotropy to the film surface and a variable magnetization direction, and a nonmagnetic layer between the first magnetic layer and the second magnetic layer. The magnetic film includes amorphous phases and crystals whose particle sizes are 0.5 nm or more.Type: ApplicationFiled: September 16, 2011Publication date: March 22, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Eiji KITAGAWA, Tadaomi Daibou, Yutaka Hashimoto, Masaru Tokou, Tadashi Kai, Makoto Nagamine, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando