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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Patent number: 8659103Abstract: According to one embodiment, a magnetoresistive element includes the following configuration. A first magnetic layer has an invariable magnetization. A second magnetic layer has a variable magnetization. A nonmagnetic layer is provided between the first and the second magnetic layers. The first magnetic layer has a structure in which first, second and third magnetic material films and a nonmagnetic material film are stacked. The first magnetic material film is provided in contact with the nonmagnetic layer, the nonmagnetic material film is provided in contact with the first magnetic material film, the second magnetic material film is provided in contact with the nonmagnetic material film, and the third magnetic material film is provided in contact with the second magnetic material film. The second magnetic material film has a Co concentration higher than that of the first magnetic material film.Type: GrantFiled: March 19, 2012Date of Patent: February 25, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Daisuke Watanabe, Katsuya Nishiyama, Toshihiko Nagase, Koji Ueda, Tadashi Kai
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Publication number: 20130329317Abstract: An example magnetic writing head includes a main magnetic pole and 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. The laminated body includes a first magnetic layer, and a second magnetic layer.Type: ApplicationFiled: August 13, 2013Publication date: December 12, 2013Applicant: 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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Publication number: 20130299929Abstract: A magnetoresistive element includes a first magnetic layer having an axis of magnetization perpendicular to the film surface and a fixed magnetization orientation; a second magnetic layer having an axis of magnetization perpendicular to the film surface and a changeable magnetization orientation; a first nonmagnetic layer arranged between the first and second magnetic layers; and a third magnetic layer having an axis of magnetization perpendicular to the film surface and a fixed magnetization orientation opposite that of the first magnetic layer. The first magnetic layer has a first magnetic material film in contact with the first nonmagnetic layer, a nonmagnetic material film in contact with the first magnetic material film, and a second magnetic material film containing Co100-xWx (0<x<40 at %) and in contact with the nonmagnetic material film. As current flows via the nonmagnetic layer, the magnetization orientation of the second magnetic layer changes.Type: ApplicationFiled: March 5, 2013Publication date: November 14, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Daisuke WATANABE, Katsuya NISHIYAMA, Toshihiko NAGASE, Koji UEDA, Tadashi KAI
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Publication number: 20130288397Abstract: 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: July 1, 2013Publication date: October 31, 2013Inventors: Eiji Kitagawa, Tadaomi Daibou, Yutaka Hashimoto, Masaru Tokou, Tadashi Kai, Makato Nagamine, Toshihiko Nagase, Katsuya Nishiyama, Koji Ueda, Hiroaki Yoda, Kay Yakushiji, Shinji Yuasa, Hitoshi Kubota, Taro Nagahama, Akio Fukushima, Koji Ando
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Patent number: 8547662Abstract: 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: GrantFiled: July 3, 2012Date of Patent: October 1, 2013Assignee: 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: 8547737Abstract: 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: September 27, 2012Date of Patent: October 1, 2013Assignee: 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: 20130249025Abstract: According to one embodiment, a magnetoresistive element includes a bottom electrode, a first magnetic layer with an magnetic axis substantially perpendicular to a film plane thereof, a first interface layer, an MgO insulating layer, a second interface layer, a second magnetic layer with an magnetic axis nearly perpendicular to a film plane thereof, and a top electrode. The magnetoresistive element has a diffusion barrier layer between the first magnetic layer and the first interface layer when the first magnetic layer contains Pt or Pd, and a diffusion barrier layer between the second magnetic layer and the second interface layer when the second magnetic layer contains Pt or Pd. The diffusion barrier layer is an Hf film of thickness 0.6 nm to 0.8 nm.Type: ApplicationFiled: September 8, 2012Publication date: September 26, 2013Applicant: Kabushiki Kaisha ToshibaInventors: Katsuaki NATORI, Toshihiko Nagase, Eiji Kitagawa, Tadashi Kai
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Patent number: 8530887Abstract: A magnetoresistive element according to an embodiment includes: a first magnetic layer; a tunnel barrier layer on the first magnetic layer; a second magnetic layer placed on the tunnel barrier layer and containing CoFe; and a nonmagnetic layer placed on the second magnetic layer, and containing nitrogen and at least one element selected from the group consisting of B, Ta, Zr, Al, and Ce.Type: GrantFiled: March 17, 2011Date of Patent: September 10, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Eiji Kitagawa, Tadashi Kai, Tadaomi Daibou, Yutaka Hashimoto, Hiroaki Yoda
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Patent number: 8530987Abstract: 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: GrantFiled: March 28, 2012Date of Patent: September 10, 2013Assignee: Kabushiki Kaisha ToshibaInventors: 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: 8502331Abstract: 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: GrantFiled: September 16, 2011Date of Patent: August 6, 2013Assignee: 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
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Patent number: 8400734Abstract: 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: March 19, 2013Assignee: 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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Publication number: 20130056349Abstract: Provided are a sputtering target including a target main body 10 that has MgO as a main component and a thickness of 3 mm or smaller, and a method of manufacturing a magnetic memory using the sputtering target which improves an MR ratio.Type: ApplicationFiled: August 31, 2012Publication date: March 7, 2013Inventors: Eiji KITAGAWA, Tadaomi DAIBOU, Kenji NOMA, Tadashi KAI, Koji YAMAKAWA, Toshihiko NAGASE, Katsuya NISHIYAMA, Koji UEDA, Daisuke WATANABE, Hiroaki YODA, Satoru SANO, Yoshihiro NISHIMURA, Takayuki WATANABE, Yuzo KATO, Akira UEKI
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Patent number: 8378437Abstract: A magnetoresistive effect element includes a reference layer, a recording layer, and a nonmagnetic layer. The reference layer is made of a magnetic material, has an invariable magnetization which is perpendicular to a film surface. The recording layer is made of a magnetic material, has a variable magnetization which is perpendicular to the film surface. The nonmagnetic layer is arranged between the reference layer and the recording layer. A critical diameter which is determined by magnetic anisotropy, saturation magnetization, and switched connection of the recording layer and has a single-domain state as a unique stable state or a critical diameter which has a single-domain state as a unique stable state and is inverted while keeping the single-domain state in an inverting process is larger than an element diameter of the magnetoresistive effect element.Type: GrantFiled: October 9, 2008Date of Patent: February 19, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Masahiko Nakayama, Kay Yakushiji, Sumio Ikegawa, Shinji Yuasa, Tadashi Kai, Toshihiko Nagase, Minoru Amano, Hisanori Aikawa, Tatsuya Kishi, Hiroaki Yoda
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Patent number: 8363462Abstract: A magnetoresistive element which records information by supplying spin-polarized electrons to a magnetic material, includes a first pinned layer which is made of a magnetic material and has a first magnetization directed in a direction perpendicular to a film surface, a free layer which is made of a magnetic material and has a second magnetization directed in the direction perpendicular to the film surface, the direction of the second magnetization reversing by the spin-polarized electrons, and a first nonmagnetic layer which is provided between the first pinned layer and the free layer. A saturation magnetization Ms of the free layer satisfies a relationship 0?Ms<?{square root over ( )}{Jw/(6?At)}. Jw is a write current density, t is a thickness of the free layer, A is a constant.Type: GrantFiled: September 15, 2011Date of Patent: January 29, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Toshihiko Nagase, Masatoshi Yoshikawa, Eiji Kitagawa, Masahiko Nakayama, Tadashi Kai, Tatsuya Kishi, Hiroaki Yoda
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Publication number: 20130020659Abstract: 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: September 27, 2012Publication date: January 24, 2013Inventors: 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: 20130010532Abstract: According to one embodiment, a magnetoresistive element includes first and second magnetic layers and a first nonmagnetic layer. The first magnetic layer has an axis of easy magnetization perpendicular to a film plane, and a variable magnetization. The second magnetic layer has an axis of easy magnetization perpendicular to a film plane, and an invariable magnetization. The first nonmagnetic layer is provided between the first and second magnetic layers. The second magnetic layer includes third and fourth magnetic layers, and a second nonmagnetic layer formed between the third and fourth magnetic layers. The third magnetic layer is in contact with the first nonmagnetic layer and includes Co and at least one of Zr, Nb, Mo, Hf, Ta, and W.Type: ApplicationFiled: March 22, 2012Publication date: January 10, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Toshihiko Nagase, Eiji Kitagawa, Katsuya Nishiyama, Tadashi Kai, Koji Ueda, Daisuke Watanabe
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Publication number: 20130009259Abstract: According to one embodiment, a magnetoresistive element includes the following configuration. A first magnetic layer has an invariable magnetization. A second magnetic layer has a variable magnetization. A nonmagnetic layer is provided between the first and the second magnetic layers. The first magnetic layer has a structure in which first, second and third magnetic material films and a nonmagnetic material film are stacked. The first magnetic material film is provided in contact with the nonmagnetic layer, the nonmagnetic material film is provided in contact with the first magnetic material film, the second magnetic material film is provided in contact with the nonmagnetic material film, and the third magnetic material film is provided in contact with the second magnetic material film. The second magnetic material film has a Co concentration higher than that of the first magnetic material film.Type: ApplicationFiled: March 19, 2012Publication date: January 10, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Daisuke WATANABE, Katsuya NISHIYAMA, Toshihiko NAGASE, Koji UEDA, Tadashi KAI
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Patent number: 8349622Abstract: A magneto-resistive element according to an aspect of the present invention includes a free layer whose magnetized state changes and a pinned layer whose magnetized state is fixed. The free layer comprises first and second ferromagnetic layers and a non-magnetic layer which is arranged between the first and second ferromagnetic layers. An intensity of exchange coupling between the first and second ferromagnetic layers is set so that an astroid curve in a hard axis direction opens.Type: GrantFiled: January 29, 2009Date of Patent: January 8, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Sumio Ikegawa, Masahiko Nakayama, Tadashi Kai, Eiji Kitagawa, Hiroaki Yoda
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Publication number: 20130001716Abstract: In accordance with an embodiment, a magnetoresistive element includes a lower electrode, a first magnetic layer on the lower electrode, a first diffusion prevention layer on the first magnetic layer, a first interfacial magnetic layer on the first metal layer, a nonmagnetic layer on the first interfacial magnetic layer, a second interfacial magnetic layer on the nonmagnetic layer, a second diffusion prevention layer on the second interfacial magnetic layer, a second magnetic layer on the second diffusion prevention layer, and an upper electrode layer on the second magnetic layer. The ratio of a crystal-oriented part to the other part in the second interfacial magnetic layer is higher than the ratio of a crystal-oriented part to the other part in the first interfacial magnetic layer.Type: ApplicationFiled: March 20, 2012Publication date: January 3, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Koji Yamakawa, Katsuaki Natori, Daisuke Ikeno, Tadashi Kai
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Publication number: 20130001713Abstract: According to one embodiment, a magnetoresistive element includes the following configuration. First nonmagnetic layer is provided between the first magnetic layer (storage layer) and the second magnetic layer (reference layer). Third magnetic layer is formed on a surface of the storage layer, which is opposite to a surface on which the first nonmagnetic layer is formed. Fourth magnetic layer is formed on a surface of the reference layer, which is opposite to a surface on which the first nonmagnetic layer is formed. The third and fourth magnetic layers have a magnetization antiparallel to the magnetization of the storage layer. Second nonmagnetic layer is located between the storage and third magnetic layers. Third nonmagnetic layer is located between the reference and fourth magnetic layers. The thickness of the fourth magnetic layer is smaller than that of the third magnetic layer.Type: ApplicationFiled: March 19, 2012Publication date: January 3, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Koji Ueda, Katsuya Nishiyama, Toshihiko Nagase, Daisuke Watanabe, Eiji Kitagawa, Tadashi Kai