Organization
Graduate School of Science Associate professor
Graduate School
Graduate School of Science
Undergraduate School
School of Science
Title
Associate professor
Contact information
KOBAYASHI, Yoshiaki
Degree 1
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Degree of Science （ 1994.3 Gakushuin University ）
Research Interests 4
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nuclear magnetic resonance
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strong correlation system
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superconductivity
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磁性体
Research Areas 1
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Others / Others / Physical Properties II
Current Research Project and SDGs 5
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鉄系超伝導体の 鉄面内異方性
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On the superconducting symmetry of iron pnictide systems
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The superconducting state of layered cobalt oxides NaxCoO2.yH2O and the electronic state of the parent compound NaxCoO2
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magnetic structure and dielectric property of LiCu2O2 in magnetically ordered phase
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The magnetic properties of Cu oxides Li2ZrCuO4 with 1-dimensoinal Cu ribbon
Research History 3
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Nagoya University Graduate School of Science Associate professor
2022.4
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Nagoya University School of Science
2022.4
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Nagoya University Graduate School of Science
2022.4
Education 2
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Gakushuin University Graduate School, Division of Science and Technology
1991.4 - 1994.3
Country： Japan
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Gakushuin University Graduate School, Division of Science and Technology
1989.4 - 1991.3
Country： Japan
Professional Memberships 2
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The Physical Society of Japan
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The Japanese Society for Neutron Science Affiliate
2013.11
Committee Memberships 1
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極低温実験室運営委員会 委員長
2021.4
Papers 153
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75As Nuclear Spin–Spin Relaxation Measurement in Iron-Pnictide Superconductor Ba0.66K0.34Fe2As2 Reviewed
Yoshihiko Ota, Taku Matsushita, Shigeyuki Ishida, Akira Iyo, Hiroshi Eisaki, and Yoshiaki Kobayashi
Journal of the Physical Society of Japan Vol. 93 page： 044711-1 - 044711-7 2024.4
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Spin Dynamics Studied by 77Se Nuclear Spin-Echo Decay Measurements in FeSe Reviewed
Yoshihiko Ota, Taku Matsushita, Hiromasa Kobayashi, and Yoshiaki Kobayashi
Journal of the Physical Society of Japan Vol. 93 page： 033701-1 - 033701-4 2024.2
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Multipole Fluctuation of Iron Pnictide Superconductor Ba(Fe1−xCox)2As2 Reviewed
Haruyasu Sato, Mitsuhiro Akatsu, Yuichi Nemoto, Terutaka Goto, Ryosuke Kurihara, Keisuke Mitsumoto, Yoshiaki Kobayashi, and Masatoshi Sato
JPS Conference Proceedings Vol. 30 page： 011052-1 - 011052-6 2020
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In-plane anisotropy of the electric field gradient in Ba(Fe1-xCox)(2)As-2 observed by As-75 NMR
Toyoda Masayuki, Ichikawa Akihiro, Kobayashi Yoshiaki, Sato Masatoshi, Itoh Masayuki
PHYSICAL REVIEW B Vol. 97 ( 17 ) 2018.5
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X-ray diffraction study of spontaneous strain in the iron-based superconductor Sr4V2Fe2As2O6-delta Reviewed
M. Saito, H. Fujishita, H. Okamoto, Y. Kobayashi, M. Sato
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 519 page： 142 - 146 2015.12
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X-ray diffraction study of spontaneous strain in Fe-pnictide superconductor, NdFeAsO0.89F0.11
Fujishita H., Hayashi Y., Saito M., Unno H., Kaneko H., Okamoto H., Ohashi M., Kobayashi Y., Sato M.
EUROPEAN PHYSICAL JOURNAL B Vol. 85 ( 2 ) 2012.2
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V-51-NMR studies on the spin dynamics of S=1/2 zig-zag chains of VO5 pyramids
Kobayashi Y, Fukamachi T, Kanada M, Harashina H, Tanaka S, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 1 ) page： 273 - 278 1999.1
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Observation of Ferro-Quadrupole Quantum Criticality in Iron Pnictide Superconductor Ba(Fe1−xCox)2As2 Invited Reviewed
Haruyasu Sato, Mitsuhiro Akatsu, Ryosuke Kurihara, Yoshiaki Kobayashi, and Yuichi Nemoto
Journal of the Physical Society of Japan Vol. 92 ( 12 ) page： 124710-1 - 124710-12 2023.11
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NMR Evidence for Majorana Gap in the Kitaev Quantum Spin Liquid Reviewed
Junya Yamamoto, Yuya Nagai, Takaaki Jinno, Yasuhiro Shimizu, Taku Matsushita,Yoshiaki Kobayashi, Masayuki Itoh, Joji Nasu, Yukitoshi Motome
JPS Conf. Proc. Vol. 38 page： 011130-1 - 011130-5 2023
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Tailoring a new oxyhydride, CaVO3-xHx, with ordered hydride anions Invited Reviewed
Yutaka Ueda, Yoshiaki Kobayashi, Masayuki Itoh
Journal of Solid State Chemistry Vol. 24 page： 122685 2021.10
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Ultralow-energy magnon anomaly in yttrium iron garnet Reviewed
Shamoto Shin-ichi, Yasui Yukio, Matsuura Masato, Akatsu Mitsuhiro, Kobayashi Yoshiaki, Nemoto Yuichi, Ieda Jun'ichi
PHYSICAL REVIEW RESEARCH Vol. 2 ( 3 ) 2020.8
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Successive magnetic transitions and spin structure in the two-leg ladder compound CsFe2Se3 observed by Cs-133 and Se-77 NMR Reviewed
Murase Mina, Okada Kaoru, Kobayashi Yoshiaki, Hirata Yasuyuki, Hashizume Kazuki, Aoyama Takuya, Ohgushi Kenya, Itoh Masayuki
PHYSICAL REVIEW B Vol. 102 ( 1 ) 2020.7
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Observation of a Novel Phase Transition in Sr(7)Re(4)O19 Reviewed
Ueda Yutaka, Murase Mina, Kobayashi Yoshiaki, Itoh Masayuki, Yajima Takeshi, Yamaguchi Tomoki, Takahashi Ryo, Sugimoto Koudai, Ohta Yukinori
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 89 ( 5 ) 2020.5
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Local structure study of the iron-based systems of BaFe2As2 and LiFeAs by X-ray PDF and XAFS analyses
Li S., Toyoda M., Kobayashi Y., Itoh M., Ikeuchi K., Yoneda Y., Otani A., Matsumura D., Asano S., Mizuki J., Sato M.
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 555 page： 45 - 53 2018.12
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Magnetic excitation and local magnetic susceptibility of the excitonic insulator Ta2NiSe5 investigated by Se-77 NMR
Li Shang, Kawai Shunsuke, Kobayashi Yoshiaki, Itoh Masayuki
PHYSICAL REVIEW B Vol. 97 ( 16 ) 2018.4
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Nematic fluctuations in iron arsenides NaFeAs and LiFeAs probed by As-75 NMR
Toyoda Masayuki, Kobayashi Yoshiaki, Itoh Masayuki
PHYSICAL REVIEW B Vol. 97 ( 9 ) 2018.3
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Critical Slowing Down of Quadrupole and Hexadecapole Orderings in Iron Pnictide Superconductor
Kurihara Ryosuke, Mitsumoto Keisuke, Akatsu Mitsuhiro, Nemoto Yuichi, Goto Terutaka, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 86 ( 6 ) 2017.6
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Fast recovery of the stripe magnetic order by Mn/Fe substitution in F-doped LaFeAsO superconductors Reviewed
M. Moroni, P. Carretta, G. Allodi, R. De Renzi, M. N. Gastiasoro, B. M. Andersen, P. Materne, H. H. Klauss, Y. Kobayashi, M. Sato, S. Sanna
PHYSICAL REVIEW B Vol. 95 ( 18 ) page： 180501 2017.5
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Metal-insulator transition and magnetic fluctuations in polycrystalline Ru1-xRhxP investigated by 31P NMR Reviewed
S. Li, Y. Kobayashi, M. Itoh, D. Hirai, and H. Takagi
PHYSICAL REVIEW B Vol. 95 ( 15 ) page： 155137 2017.4
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Local electronic state in the half-metallic ferromagnet CrO2 investigated by site-selective 53Cr NMR measurements Reviewed
Hikaru Takeda, Yasuhiro Shimizu, Yoshiaki Kobayashi, Masayuki Itoh, Takaaki Jin-no, Masahiko Isobe, Yutaka Ueda, Sho Yoshida, Yuji Muraoka, Takayoshi Yokoya
PHYSICAL REVIEW B Vol. 93 ( 23 ) page： 235129 2016.6
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Phonons of Fe-based superconductor Ca10Pt4As8(Fe1-xPtxAs)10 Reviewed
K. keuchi, Y. Kobayashi, K. Suzuki, M. Itoh, R. Kajimoto, P. Bourges, A. D. Christianson, H. Nakamura, M. Machida, M. Sato
JOURNAL OF PHYSICS-CONDENSED MATTER Vol. 27 ( 46 ) page： 465701 2015.11
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Enhancement of low-frequency fluctuations and superconductivity breakdown in Mn-doped La1-yYyFeAsO0.89F0.11 superconductors Reviewed
F. Hammerath, M. Moroni, L. Bossoni, S. Sanna, R. Kappenberger, S. Wurmehl, A. U. B. Wolter, M. A. Afrassa, Y. Kobayashi, M. Sato, B. Buchner, P. Carretta
PHYSICAL REVIEW B Vol. 92 ( 2 ) page： 020505 2015.7
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Identification of Various Coexisting Phases in Superconducting and Non-superconducting Samples of RbxFe2-ySe2
Kobayashi Yoshiaki, Kototani Shohei, Ohishi Kazuki, Itoh Masayuki, Hoshikawa Akinori, Ishigaki Toru, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 84 ( 4 ) 2015.4
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Detailed Study of the Phase Diagram of Fe-based Superconductor Ba (Fe1-x Co x) 2As2 by Super High-Resolution Neutron Diffraction Measurements Invited Reviewed
K Ikeuchi, M Sato, S Li, M Toyoda, Y Kobayashi, M Itoh, P Miao, S Torii, Y Ishikawa, T Kamiyama
Journal of Physics: Conference Series Vol. 592 ( 1 ) page： 012071_1 - 012071_5 2015.3
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Identification of Various Coexisting Phases in Superconducting and Non-superconducting Samples of RbxFe2-ySe2 Reviewed
Yoshiaki Kobayashi, Shohei Kototani, Kazuki Ohishi, Masayuki Itoh, Akinori Hoshikawa, Toru Ishigaki, Masatoshi Sato
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 84 ( 4 ) page： 044710 2015
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Phonons and Spin Excitations in Fe-Based Superconductor Ca10Pt4As8(Fe1-xPtxAs)10 (x~0.2) Reviewed
K. Ikeuchi, M. Sato, R. Kajimoto, Y. Kobayashi, K. Suzuki, M. Itoh, P. Bourges, A. D. Christianson, H. Nakamura, and M. Machida
JPS Conf. Proc. Vol. 3 page： 015043-(1-6) 2014.6
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On the Superconducting Symmetry of Fe-Based Systems -Impurity Effects and Microscopic Magnetic Behavior- Reviewed
M. Sato, K. Ikeuchi, R. Kajimoto, Y. Kobayashi, Y. Yasui, K. Suzuki, M. Itoh, M. Nakamura, Y. Inamura, M. Arai, P. Bourges, A. D. Christianson, H. Nakamura, and M. Machida
JPS Conf. Proc. Vol. 1 page： 014007-(1-12) 2014.3
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Poisoning effect of Mn in LaFe1-xMnxAsO0.89F0.11: Unveiling a quantum critical point in the phase diagram of iron-based superconductors Reviewed
F. Hammerath, P. Bonfa, S. Sanna, G. Prando, R. D. Renzi, Y. Kobayashi, M. Sato, and P. Carretta
Phys. Rev. B Vol. 89 page： 134503 2014.3
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Spin disorder in an Ising honeycomb chain cobaltate
Igarashi Hirokazu, Shimizu Yasuhiro, Kobayashi Yoshiaki, Itoh Masayuki
PHYSICAL REVIEW B Vol. 89 ( 5 ) 2014.2
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Spin disorder in an Ising honeycomb chain cobaltate Reviewed
Hirokazu Igarashi, Yasuhiro Shimizu, Yoshiaki Kobayashi, and Masayuki Itoh
Phys. Rev. B Vol. 89 page： 054431-(1-5) 2014.2
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75As NQR and NMR Studies on the Superconducting State of Ca10Pt4As8(Fe1-xPtxAs)10 Reviewed
Y. Kobayashi, T. Iida, K. Suzuki, T. Kawamata, M. Itoh, and M. Sato
J. Phys. Soc. Jpn. Vol. 83 ( 1 ) page： 014712-(1-6) 2013.12
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In-plane Anisotropy of the Magnetic and the Electric Properties of the Fe Pnictide Ba(Fe1-xCox)2As2
Y. Kobayashi, A. Ichikawa, M. Toyoda, M. Itoh, and M. Sato
Journal of the Korean Physical Society Vol. 63 page： 481-485 2013.9
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Phase Separation of Antiferromagnetism and Superconductivity in RbxFe2-ySe2 Observed by using Rb NMR Reviewed
Y. Kobayashi, S. Saiki, S. Kototani, M. Itoh, and M. Sato
Journal of the Korean Physical Society Vol. 63 page： 448-452 2013.9
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Magnetism and superconductivity in Rb (x) Fe2-y Se-2
Ohishi Kazuki, Sato Masatoshi, Kototani Shouhei, Saiki Shunsuke, Kobayashi Yoshiaki, Itoh Masayuki
JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 62 ( 12 ) page： 1994 - 1996 2013.7
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Magnetism and superconductivity in RbxFe2-ySe2 Reviewed
Kazuki Ohishi, Masatoshi Sato, Shouhei Kototani, Shunsuke Saiki, Yoshiaki Kobayashi, Masayuki Itoh
Journal of the Korean Physical Society Vol. 62 ( 12 ) page： 1994-1996 2013
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On the superconducting symmetry of Fe-based systems - Impurity effect studies and neutron scattering measurements Reviewed
Masatoshi Sato, Yoshiaki Kobayashi, Takayuki Kawamata, Yukio Yasui, Kazunori Suzuki, Masayuki Itoh,. Ryoichi Kajimoto, Kazuhiko Ikeuchi, Masatoshi Arai, Phillipe Bourges
Journal of the Korean Physical Society Vol. 62 ( 12 ) page： 1726-1733 2013
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Onset of magnetism in optimally electron-doped LFe1-xRuxAsO1-yFy (L = La, Nd, or Sm) superconductors around x=1/4,
S. Sanna, P. Carretta, R. De Renzi, G. Prando, P. Bonfà, M. Mazzani, G. Lamura, T. Shiroka, Y. Kobayashi, and M. Sato
Phys. Rev. B Vol. 87 page： 134518-(1-6) 2013
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On the superconducting pairing mechanism of Fe-based systems-Is it new or well-known? Reviewed
M. Sato and Y. Kobayashi
Solid State Communications Vol. 152 ( 8 ) page： 688–694 2012.8
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X-ray diffraction study of spontaneous strain in Fe-pnictide superconductor, NdFeAsO0.89F0.11 Reviewed
H. Fujishita, Y. Hayashi, M. Saito, H. Unno, H. Kaneko, H. Okamoto, M. Ohashi, Y. Kobayashi, M. Sato
European Physical Journal B Vol. 85 ( 2 ) page： 52 2012.2
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Study of magnetic excitation spectra of several Fe-pnictide systems Reviewed
M Sato, T Kawamata, Y Kobayashi, Y Yasui, T Iida, K Suzuki, M Itoh, T Moyoshi, K Motoya, R Kajimoto, M Nakamura, Y Inamura and M Arai
Journal of Physics: Conference Series Vol. 400 page： 022105 2012
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Impurity effects on the superconducting transition temperatures of Fe pnictides and superconducting symmetry of the order parameter Reviewed
M. Sato, Y. Kobayashi, S. Satomi, T. Kawamata and M. Itoh
Journal of Physics: Conference Series Vol. 400 page： 022104 2012
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NMR Studies on Iron Pnictide Superconductors of LaFeAsO0.89F0.11 and Ca-Fe-Pt-As Reviewed
Y. Kobayashi, T. Iida, K. Suzuki, E. Satomi, T. Kawamata, M. Itoh, and M. Sato
Journal of Physics: Conference Series Vol. 400 page： 022056 2012
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Absence of Magnetic Order in Ising Honeycomb-Lattice Ba3Co2O6(CO3)(0.7)
Igarashi Kazuhiro, Shimizu Yasuhiro, Satomi Erika, Kobayashi Yoshiaki, Takami Tsuyoshi, Itoh Masayuki
26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5 Vol. 400 2012
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NMR Studies on Iron Pnictide Superconductors of LaFeAsO0.89F0.11 and Ca-Fe-Pt-As
Kobayashi Y., Iida T., Suzuki K., Satomi E., Kawamata T., Itoh M., Sato M.
26TH INTERNATIONAL CONFERENCE ON LOW TEMPERATURE PHYSICS (LT26), PTS 1-5 Vol. 400 2012
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Magnetic Excitation Spectra of Superconducting Ca-Fe-Pt-As System Reviewed
M. Sato, T. Kawamata, Y. Kobayashi, Y. Yasui, Takefumi Iida, Kazunori Suzuki, Masayuki Itoh, Taketo Moyoshi, Kiyoichiro Motoya, Ryoichi Kajimoto, Mitsutaka Nakamura, Yasuhiro Inamura, and Masatoshi Arai
Journal of the Physical Society of Japan Vol. 80 page： 093709-(1-4) 2011
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Crystal Structure of New Pt-Doped Fe Pnictide Superconductors Reviewed
Vol. 80 page： 073710-(1-3) 2011
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Study of Ni-Doping Effect of Specific Heat and Transport Properties for LaFe1-yNiyAsO0.89F0.11 Reviewed
T. Kawamata, E. Satomi, Y. Kobayashi, M. Itoh, and M. Sato
Journal of the Physical Society of Japan Vol. 80 page： 084720-(1-5) 2011
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Magnetic Ordering in V-Layers of the Superconducting System of Sr2VFeAsO3 Reviewed
S. Tatematsu, E. Satomi, Y. Kobayashi, and M. Sato
J. Phys. Soc. Jpn. Vol. 79 ( 12 ) page： 123712-(1-4) 2010.12
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Distinct physical behaviors of LaFe1-yCoyAsO0.89F0.11 between the superconducting and nonsuperconducting metallic regions of y divided by y similar to 0.05
Sato M., Kobayashi Y., Lee S. C., Takahashi H., Moyoshi T.
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 page： S475 - S477 2010.12
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On the non-superconducting state in the phase diagram of NaxCoO2 center dot yH(2)O
Sato Masatoshi, Kobayashi Yoshiaki, Moyoshi Taketo
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 page： S752 - S754 2010.12
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NMR studies on the superconducting symmetry of iron pnictide systems
Kobayashi Yoshiaki, Lee Sang Chul, Takahashi Hidefumi, Moyoshi Taketo, Sato Masatoshi
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 page： S472 - S474 2010.12
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Magnetic excitations of superconducting LaFeAsO0.89F0.11
Moyoshi T., Lee S. C., Tatematsu S., Yasui Y., Kobayashi Y., Sato M., Kakurai K.
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 page： S470 - S471 2010.12
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Studies on the superconducting state of NaxCoO2 center dot yH(2)O - Overview
Sato Masatoshi, Kobayashi Yoshiaki, Moyoshi Taketo
PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Vol. 470 page： S673 - S677 2010.12
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75As-NMR Studies of LaFeAsO1-xFx for Various x Values Reviewed
Yoshiaki Kobayashi, Erika Satomi, Sang Chul Lee, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 79 ( 9 ) page： 093709-(1-4) 2010.9
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Erika Satomi, Sang Chul Lee, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 79 ( 9 ) page： 094702 (6 pages) 2010.9
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High-Temperature Multiferroic State of RBaCuFeO5 (R = Y, Lu, and Tm)
Kawamura Yuji, Kai Takahiro, Satomi Erika, Yasui Yukio, Kobayashi Yoshiaki, Sato Masatoshi, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 79 ( 7 ) 2010.7
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Superconducting transition temperature and the thickness of CoO2 planes of NaxCoO2 center dot yH(2)O
Moyoshi Taketo, Kobayashi Yoshiaki, Yasui Yukio, Sato Masatoshi, Kakurai Kazuhisa
SOLID STATE SCIENCES Vol. 12 ( 5 ) page： 656 - 659 2010.5
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Sang Chul Lee, Erika Satomi, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 79 ( 2 ) page： 023702-(1-4) 2010.2
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Studies on Effects of Impurity Doping and NMR Measurements of La 1111 and/or Nd 1111 Fe-Pnictide Superconductors Reviewed
Masatoshi Sato, Yoshiaki Kobayashi, Sang Chul Lee, Hidefumi Takahashi, Erika Satomi, and Yoko Miura
Journal of the Physical Society of Japan Vol. 79 ( 1 ) page： 014710-(1-10) 2010.1
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NMR studies on the superconducting symmetry of iron pnictide systems Reviewed
Y. Kobayashi, S.C. Lee, H. Takahashi, T. Moyoshi, M. Sato
Physica C: Superconductivity Vol. 470 page： S472-S474 2010
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Masatoshi Sato, Yoshiaki Kobayashi, Sang Chul Lee, Hidefumi Takahashi, Erika Satomi, and Yoko Miura
Journal of the Physical Society of Japan Vol. 79 ( 1 ) page： 014710 2009.12
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Studies of Multiferroic System LiCu2O2: I. Sample Characterization and Relationship between Magnetic Properties and Multiferroic Nature Reviewed
Yukio Yasui, Kenji Sato, Yoshiaki Kobayashi, and Masatoshi Sato
J. Phys. Soc. Jpn. Vol. 78 ( 8 ) page： 084720-(1-5) 2009.8
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*Studies of Multiferroic System of LiCu2O2: II. Magnetic Structures of Two Ordered Phases with Incommensurate Modulations Reviewed
Yoshiaki Kobayashi, Kenji Sato, Yukio Yasui, Taketo Moyoshi, Masatoshi Sato, and Kazuhisa Kakurai
Journal of the Physical Society of Japan Vol. 78 ( 8 ) page： 084721-(1-5) 2009.8
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Studies of Multiferroic System LiCu2O2: I. Sample Characterization and Relationship between Magnetic Properties and Multiferroic Nature
Yasui Yukio, Sato Kenji, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 78 ( 8 ) 2009.8
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Studies of Multiferroic System of LiCu2O2: II. Magnetic Structures of Two Ordered Phases with Incommensurate Modulations
Kobayashi Yoshiaki, Sato Kenji, Yasui Yukio, Moyoshi Taketo, Sato Masatoshi, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 78 ( 8 ) 2009.8
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*Studies on Superconducting LaFe1-yCoyAsO1-xFx (x=0.11) - for the Understanding of the Superconducting Symmetry of Fe-Pnictides - Reviewed
Yoshiaki Kobayashi, Ayaka Kawabata, Sang Chul Lee, Taketo Moyoshi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 78 ( 7 ) page： 073704-(1-4) 2009.7
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Studies on Superconducting LaFe1-yCoyAsO1-xFx (x=0.11) -For the Understanding of the Superconducting Symmetry of Fe-Pnictides-
Kobayashi Yoshiaki, Kawabata Ayaka, Lee Sang Chul, Moyoshi Taketo, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 78 ( 7 ) 2009.7
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Distinct Transport Behaviors of LaFe1-yCoyAsO1-xFx (x=0.11) between the Superconducting and Nonsuperconducting Metallic y Regions Divided by y~0.05 Reviewed
Sang Chul Lee, Ayaka Kawabata, Taketo Moyoshi, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 78 ( 4 ) page： 043703-(1-4) 2009.4
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Distinct Transport Behaviors of LaFe1-yCoyAsO1-xFx (x=0.11) between the Superconducting and Nonsuperconducting Metallic y Regions Divided by y similar to 0.05
Lee Sang Chul, Kawabata Ayaka, Moyoshi Taketo, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 78 ( 4 ) 2009.4
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Studies of the superconductivity of LaFe1-yCoyAsO1-xFx (x=0.11) -impurity effect and NMR Knight shift-
Kawabata Ayaka, Lee Sang Chul, Moyoshi Taketo, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 page： 147 - 148 2008.11
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Studies of the Superconductivity of LaFe1-yCoyAsO1-xFx Reviewed
Ayaka Kawabata, Sang Chul Lee, Taketo Moyoshi, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 77 ( 10 ) page： 103704-(1-4) 2008.10
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Superconductivity of LaFe1-yCoyAsO1-xFx
Kawabata Ayaka, Lee Sang Chul, Moyoshi Taketo, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 10 ) 2008.10
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Isotope Effect on Superconducting Transition Temperature of NaxCoO2·yH2O Reviewed
Mai Yokoi, Yoshiaki Kobayashi, Masatoshi Sato, and Shunji Sugai
Journal of the Physical Society of Japan Vol. 77 ( 9 ) page： 094713-(1-4) 2008.9
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Studies of the Superconductivity of LaFe1-yCoyAsO1-xFx (x=0.11) -Impurity Effect and NMR Knight Shift- Reviewed
Ayaka Kawabata, Sang Chul Lee, Taketo Moyoshi, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of JapanSupplement C Vol. 77 page： 147-148 2008.9
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Isotope effect on superconducting transition temperature of NaxCoO2 center dot yH(2)O
Yokoi Mai, Kobayashi Yoshiaki, Sato Masatoshi, Sugai Shunji
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 9 ) 2008.9
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Magnetic Excitations of NaxCoO2·yD2O -Neutron Scattering- Reviewed
Taketo Moyoshi, Yukio Yasui, Yoshiaki Kobayashi, Masatoshi Sato, and Kazuhisa Kakurai
Journal of the Physical Society of Japan Vol. 77 ( 7 ) page： 073709-(1-4) 2008.7
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NMR Studies of Successive Phase Transitions in Na0.5CoO2 and K0.5CoO2 Reviewed
Mai Yokoi, Yoshiaki Kobayashi, Taketo Moyoshi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 77 ( 7 ) page： 074704-(1-4) 2008.7
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Magnetic excitations of NaxCoO2 center dot yD(2)O - Neutron scattering
Moyoshi Taketo, Yasui Yukio, Kobayashi Yoshiaki, Sato Masatoshi, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 7 ) 2008.7
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NMR studies of successive phase transitions in Na0.5CoO2 and K0.5CoO2
Yokoi Mai, Kobayashi Yoshiaki, Moyoshi Taketo, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 7 ) 2008.7
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Co-NMR Knight Shift of NaxCoO2·yH2O Studied in Both Superconducting Regions of the Tc-νQ3 Phase Diagram Divided by the Nonsuperconducting Phase Reviewed
Yoshiaki Kobayashi, Taketo Moyoshi, Mai Yokoi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 77 ( 6 ) page： 063703-(1-4) 2008.6
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Co-NMR knight shift of NaxCoO2 center dot yH(2)O studied in both superconducting regions of the T-c-nu(Q3) phase diagram divided by the nonsuperconducting phase
Kobayashi Yoshiaki, Moyoshi Taketo, Yokoi Mai, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 6 ) 2008.6
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On the Magnetic Structure of Quasi One Dimensional Spin 1/2 System of Li2ZrCuO4 Reviewed
Yasuko Tarui, Yoshiaki Kobayashi, and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 77 ( 4 ) page： 043703-(1-4) 2008.4
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On the magnetic structure of quasi one dimensional spin 1/2 system of Li2ZrCuO4
Tarui Yasuko, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 77 ( 4 ) 2008.4
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T-3nQ Phase Diagram of Hydrated Cobait Oxides NaxCoO2.yH2O Reviewed
Yoshiaki Kobayashi, Mai Yokoi, Taketo Moyosi and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 76 ( 10 ) page： 103705-(1-5) 2007.10
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T-3v(Q) phase diagram of hydrated cobalt oxides Na(x)CoO(2 center dot)yH(2)O
Kobayashi Yoshiaki, Yokoi Mai, Moyoshi Taketo, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 76 ( 10 ) 2007.10
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Magnetic Behavior of Spin-1/2 Frustrated System Hg2Cu2F6S Reviewed
Shohei Kawabata, Yukio Yasui, Yoshiaki Kobayashi and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 76 ( 8 ) page： 084705-(1-5) 2007.8
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Magnetic Behavior of spin-1/2 frustrated system Hg2Cu2F6S
Kawabata Shohei, Yasui Yukio, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 76 ( 8 ) 2007.8
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Spin-gap behavior of distorted honeycomb lattice system Na3Cu2SbO6
Miura Yoko, Hirai Riu, Fujita Toshiaki, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： E389 - E391 2007.3
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NMR studies of successive transition in Na0.5CoO2
Kobayashi Y., Yokoi M., Moyoshi T., Watanabe H., Sato M.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 675 - 677 2007.3
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NMR and neutron scattering studies on NaxCoO2 center dot yH(2)O
Sato M., Kobayashi Y., Moyoshi T., Yokoi M., Watanabe H., Mori Y., Kakurai K.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 666 - 668 2007.3
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Magnetic and thermal properties of Co3V2O8 and Ni3V2O8
Kobayashi Yusuke, Yasui Yukio, Sato Masatoshi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 1160 - 1161 2007.3
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Studies of successive transitions in K0.5CoO2
Yokoi Mai, Mori Yoshihiko, Moyoshi Taketo, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 672 - 674 2007.3
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Ferroelectric transition induced by the incommensurate magnetic ordering in LiCuVO4
Naito Yutaka, Sato Kenji, Yasui Yukio, Kobayashi Yusuke, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 76 ( 2 ) 2007.2
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Structural studies of pyrochlore-related spin-1/2 system Ag2Cu2O3
Uematsu Daisuke, Soda Minoru, Kobayashi Yoshiaki, Sato Masatoshi, Igawa Naoki, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 12 ) 2006.12
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Existence of Co3+ low-spin state in TbBaCo2O5.5
Soda Minoru, Yasui Yukio, Kobayashi Yoshiaki, Fujita Toshiaki, sato Mashi Sato, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 10 ) 2006.10
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Spin-Gap Behavior of Na3Cu2SbO6 with Distorted Honeycomb Structure Reviewed
Yoko Miura, Riu Hirai, Yoshiaki Kobayashi and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 75 ( 8 ) page： 084707-(1-6) 2006.8
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Spin-gap behavior of Na3Cu2SbO6 with distorted honeycomb structure
Miura Yoko, Hirai Riu, Kobayashi Yoshiaki, Sato Masatoshi
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 8 ) 2006.8
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Magnetic properties of Superconducitng Cobait Oxides NaxCoO2.yH2O Reviewed
Yoshiaki Kobayshi, taketo Moyoshi, Hidekazu Watanabe Mai Yokoi and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 75 ( 7 ) page： 074717-(1-6) 2006.7
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Search for Magnetic Excitation Spectra of NaxCoO2.yD2O -Neutron Scattering- Reviewed
Taketo Moyoshi, Yukio Yasui, Minoru Soda, Yoshiaki Kobayashi, Masatoshi Sato and Kazuhisa Kakurai
Journal of the Physical Society of Japan Vol. 75 ( 7 ) page： 074705-(1-6) 2006.7
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Magnetic properties of superconducting cobalt oxides NaxCoO2 center dot yH(2)O
Kobayashi Yoshiaki, Moyoshi Taketo, Watanabe Hidekazu, Yokoi Mai, sato Mashi Sato
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 7 ) 2006.7
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Search for magnetic excitation spectra of NaxCoO2 center dot yD(2)O - Neutron scattering
Moyoshi Taketo, Yasui Yukio, Soda Minoru, Kobayashi Yoshiaki, Sato Masatoshi, Kakurai Kazuhisa
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 7 ) 2006.7
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Magnetic and metal-insulator transitions in beta-Na0.5CoO2 and gamma-K0.5CoO2 - NMR and neutron diffraction studies
Watanabe H, Mori Y, Yokoi M, Moyoshi T, Soda M, Yasui Y, Kobayashi Y, Sato M, Igawa N, Kakurai K
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 75 ( 3 ) 2006.3
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*Magnetic correlation of NaxCoO2 and Successive Phase Transitions of Na0.5CoO2 -NMR and Neutron Diffraction Studies- Reviewed
Mai Yokoi, Taketo Moyoshi, Yoshiaki Kobayashi, Munoru Soda, Yukio Yasui, Masatoshi Sato and Kazushi Kakurai
Journal of the Physical Society of Japan Vol. 74 ( 11 ) page： 3046-3056 2005.11
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Co-59-NMR Knight shift of superconducting three-layer NaxCoO2 center dot yH(2)O
Watanabe H, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 74 ( 9 ) page： 2563 - 2567 2005.9
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59Co-NMR Knight shift of Aligned Crystal and Polycrystalline Samples of Superconducting Na0.3CoO2.1.3H2O Reviewed
Yoshiaki Kobayashi, Hidekazu Watanabe, Mai Yokoi, Taketo Moyoshi, Yoshihiko Mori and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 74 ( 6 ) page： 1800-1805 2005.6
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Co-59-NMR knight shift of aligned crystals and polycrystalline samples of superconducting Na0.3CoO2 center dot 1.3H(2)O
Kobayashi Y, Watanabe H, Yokoi M, Moyoshi T, Mori Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 74 ( 6 ) page： 1800 - 1805 2005.6
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ESR studies on quasi one-dimensional spin system TiOBr
Kato C, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 74 ( 1 ) page： 473 - 477 2005.1
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Magnetic structure of a spinel system Cu0.3Zn0.7Cr2Se4
Iikubo S, Yasui Y, Kobayashi Y, Ohno Y, Ito M, Soda M, Sato M, Kakurai K
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 272 page： 473 - 474 2004.5
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Impurity effects on the superconducting transition temperature of NazCoO2 center dot yH(2)O
Yokoi M, Watanabe H, Mori Y, Moyoshi T, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 73 ( 5 ) page： 1297 - 1302 2004.5
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Ru-NMR studies and specific heat measurements of Bi3Ru3O11 and La4Ru6O19
Tsuchida K, Kato C, Fujita T, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 73 ( 3 ) page： 698 - 702 2004.3
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Co-59-NMR knight shift of superconducting NaxCoO2 center dot yH(2)O
Kobayashi Y, Yokoi M, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 72 ( 10 ) page： 2453 - 2455 2003.10
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Co-59 NQR study on superconducting NaxCoO2 center dot yH(2)O
Kobayashi Y, Yokoi M, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 72 ( 9 ) page： 2161 - 2164 2003.9
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NMR studies of Co-oxides with large thermoelectric performance
Kobayashi Y, Masuda H, Miyashita T, Sato M, Itoh M, Terasaki I
PHYSICA B-CONDENSED MATTER Vol. 329 page： 926 - 927 2003.5
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Spin-glass-like transition and Hall resistivity of Y2-xBixIr2O7
Aito N, Soda M, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 72 ( 5 ) page： 1226 - 1230 2003.5
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Transport, thermal and magnetic properties of pyrochlore oxides Y2-xBixIr2O7
Soda M, Aito N, Kurahashi Y, Kobayashi Y, Sato M
PHYSICA B-CONDENSED MATTER Vol. 329 page： 1071 - 1073 2003.5
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Transport, thermal and magnetic properties of Bi3Os3O11 and Bi3Ru3O11
Fujita T, Tsuchida K, Yasui Y, Kobayashi Y, Sato M
PHYSICA B-CONDENSED MATTER Vol. 329 page： 743 - 744 2003.5
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Spin-state change of co atoms of La4Co3O10+delta
Miyashita T, Kobayashi Y, Fukamachi T, Masuda H, Sato M
PHYSICA B-CONDENSED MATTER Vol. 329 page： 740 - 742 2003.5
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Transport and magnetic properties of R(1-x)A(x)CoO(3) (R = La, Pr and Nd; A = Ba, Sr and Ca)
Masuda H, Fujita T, Miyashita T, Soda M, Yasui Y, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 72 ( 4 ) page： 873 - 878 2003.4
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*59Co-NMR Knight Shift of Superconducting NaxCoO2·yH2O Reviewed
Yoshiaki Kobayashi, Mai Yokoi and Masatoshi Sato
Journal of the Physical Society of Japan Vol. 72 page： 2453-2455 2003
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Co-59-NMR studies on La4Co3O10+delta
Miyashita T, Kobayashi Y, Fukamachi T, Masuda H, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 71 ( 12 ) page： 3043 - 3046 2002.12
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Magnetic structure and the Hall resistivity of Cu1-xZnxCr2Se4
Iikubo S, Yasui Y, Oda K, Ohno Y, Kobayashi Y, Sato M, Kakurai K
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 71 ( 11 ) page： 2792 - 2799 2002.11
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Transport and NQR studies of Nd1.6-xCexSr0.4CuO4 with T* structure
Ambai M, Kobayashi Y, Iikubo S, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 71 ( 2 ) page： 538 - 542 2002.2
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Unusual anomalous Hall resistivities of CuCr2S4, Cu0.5Zn0.5Cr2Se4 and Cr3Te4
Oda K, Yoshii S, Yasui Y, Ito M, Ido T, Ohno Y, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 70 ( 10 ) page： 2999 - 3005 2001.10
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Studies on successive electronic state changes in systems with NiO2 planes-La-139-NMR/NQR-
Fukamachi T, Oda K, Kobayashi Y, Miyashita T, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 70 ( 9 ) page： 2757 - 2764 2001.9
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Cu NQR study on the "wipeout" phenomenon in YBa2Cu3Oy
Kobayashi Y, Miyashita T, Ambai M, Fukamachi T, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 70 ( 4 ) page： 1133 - 1136 2001.4
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La-139 NMR studies of layered perovskite systems La3Ni2O7-delta and La4Ni3O10
Fukamachi T, Kobayashi Y, Miyashita T, Sato M
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 62 ( 1-2 ) page： 195 - 198 2001
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NMR studies of Ga in magnetically frustrated pyrochlore system R2GaSbO7 (R = rare earth elements)
Kobayashi Y, Miyashita T, Fukamachi T, Sato M
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 62 ( 1-2 ) page： 347 - 350 2001
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Absence of the "wipeout" phenomenon in the NQR spectra of YBa2Cu3O6.61
Kobayashi Y, Miyashita T, Ambai M, Fukamachi T, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 69 ( 8 ) page： 2435 - 2438 2000.8
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On the anomalous oxygen-number dependence of the superconducting transition temperature of R1-xPrxBa2Cu3O6+y (R=Y and Sm)
Ambai M, Yasui Y, Takeda J, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 69 ( 1 ) page： 170 - 177 2000.1
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Magnetization measurements and Rb-87-NMR on Rb2M3S4 (M=Ni and Pd) with the Kagome lattice
Fukamachi T, Kobayashi Y, Nakamura A, Harashina H, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 11 ) page： 3668 - 3672 1999.11
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Effects of short range spin correlation on ESR lines of low-dimensional antiferromagnetic and spin-gapped systems
Taniguchi S, Kato M, Kodama K, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 6 ) page： 2118 - 2127 1999.6
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Thermal conductivity of BaCo1-xNixS2
Takeda J, Sakurai J, Nakamura A, Kato M, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 68 ( 5 ) page： 1602 - 1606 1999.5
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On the magnetic properties of systems with low dimensional linkage of VO5 pyramids
Kanada M, Harashina H, Tanaka S, Fukamachi T, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 67 ( 8 ) page： 2904 - 2909 1998.8
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NMR studies on spin-gap behavior of monoclinic CuNb2O6
Fukamachi T, Kobayashi Y, Kanada M, Kasai M, Yasui Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 67 ( 6 ) page： 2107 - 2111 1998.6
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Spin-gap behavior of CuNb2O6
Kodama K, Fukamachi T, Harashina H, Kanada M, Kobayashi Y, Kasai M, Sasaki H, Sato M, Kakurai K
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 67 ( 1 ) page： 57 - 60 1998.1
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V-51-NMR study of the misfit layer compounds La1.17-xSrxVS3.17
Kobayashi Y, Kasai M, Yasui Y, Nishikawa T, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 12 ) page： 4027 - 4030 1997.12
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ESR studies on CaV4O9 and CaV3O7
Taniguchi S, Kobayashi Y, Kasai M, Kodama K, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 11 ) page： 3660 - 3664 1997.11
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Electron- and photon-thermal conductivity of high-T-c systems from the underdoped insulating to the nonsuperconducting metallic phase
Kamijo H, Takeda J, Hayashi F, Ueda E, Fujiwara K, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 8 ) page： 2466 - 2472 1997.8
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Structural studies on the phase transition of La3Ni2O6.92 at about 550 K
Sasaki H, Harashina H, Taniguchi S, Kasai M, Kobayashi Y, Sato M, Kobayashi T, Ikeda T, Takata M, Sakata M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 6 ) page： 1693 - 1697 1997.6
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Study of spin-gap formation in quasi-two-dimensional S=1/2 system CaV4O9: Neutron scattering and NMR
Kodama K, Harashina H, Sasaki H, Kobayashi Y, Kasai M, Taniguchi S, Yasui Y, Sato M, Kakurai K, Mori T, Nishi M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 66 ( 3 ) page： 793 - 802 1997.3
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Transport and magnetic properties of La3Ni2O7-delta and La4Ni3O10-delta
Kobayashi Y, Taniguchi S, Kasai M, Sato M, Nishioka T, Kontani M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 65 ( 12 ) page： 3978 - 3982 1996.12
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Strong pressure effect on the electrical resistivity of BaCo1-xNixS2
Yasui Y, Kobayashi Y, Takeda J, Shamoto S, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 65 ( 9 ) page： 2757 - 2760 1996.9
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Thermal properties of two dimensional Mott system La-1.17-xSrxVS3.17
Nishikawa T, Yasui Y, Kobayashi Y, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 65 ( 8 ) page： 2543 - 2547 1996.8
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Electron and magnon contributions to the thermal conductivity of YBa2Cu3Oy (6.1<=y<=6.9) at low temperatures
Kamijo H, Kobayashi Y, Ueda E, Sato M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 65 ( 6 ) page： 1551 - 1554 1996.6
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Studies of the metal-insulator transition of misfit-layer compounds La1.17-xSrVS3.17
Nishikawa T, Yasui Y, Kobayashi Y, Sato M
PHYSICA C Vol. 263 ( 1-4 ) page： 554 - 557 1996.5
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EFFECTS OF CARRIER DOPING INTO THE MISFIT-LAYER COMPOUNDS (LA(1-Y)R(Y)S)(1+ALPHA)VS2 (R=SR AND PB) - TRANSPORT AND MAGNETIC STUDIES
YASUI Y, NISHIKAWA T, KOBAYASHI Y, SATO M, NISHIOKA T, KONTANI M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 64 ( 10 ) page： 3890 - 3896 1995.10
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SPIN GAP BEHAVIOR OF S=1/2 QUASI-2-DIMENSIONAL SYSTEM CAV4O9
TANIGUCHI S, NISHIKAWA T, YASUI Y, KOBAYASHI Y, SATO M, NISHIOKA T, KONTANI M, SANO K
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 64 ( 8 ) page： 2758 - 2761 1995.8
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TRANSPORT, MAGNETIC AND THERMAL-PROPERTIES OF BACO1-XNIXS2
TAKEDA J, KOBAYASHI Y, KODAMA K, HARASHINA H, SATO M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 64 ( 7 ) page： 2550 - 2557 1995.7
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TRANSPORT, MAGNETIC AND THERMAL-PROPERTIES OF LA3NI2O7-DELTA
TANIGUCHI S, NISHIKAWA T, YASUI Y, KOBAYASHI Y, TAKEDA J, SHAMOTO S, SATO M
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 64 ( 5 ) page： 1644 - 1650 1995.5
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1H-NMR investigation of the SDW wave-number in (TMTTF)2Br Reviewed
T. Nakamura, T. Nobutoki, Y. Kobayashi, T. Takahashi, G. Saito
Synthetic Metals(Elsevier) Vol. 70 ( 1-3 ) page： 1293 - 1294 1995.3
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Magnetic properties of the insulating state of the organic superconductor, β-[(CH3)4N][Pd(dmit)2]2 Reviewed
Synthetic Metals (Elsevier) Vol. 70 ( 1-3 ) page： 1043 - 1044 1995.3
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Observation of the coherence peak of 1H-NMR relaxation rate in the superconducting state of (MDT-TTF)2Aul2 Reviewed
Y. Kobayashi, T. Nakamura, T. Takahashi, K. Kanoda, B. Hilti, J. S. Zambounis
Synthetic Metals(Elsevier) Vol. 70 ( 1-3 ) page： 871 - 872 1995.3
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Symmetry of the order parameter in organic superconductors:(MDT-TTF) 2Aul2 vs.(TMTSF) 2ClO4 Invited Reviewed
T Takahashi, Y Kobayashi, T Nakamura, K Kamoda, B Hilti, JS Zambounis
Physica C: Superconductivity (North-Holland) Vol. 7 ( 3 ) page： 636 - 666 1994.12
Presentations 1
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75As NMR studies on the nematic state in the iron pnictide NaFeAs International conference
Masayuki Toyoda, Yoshiaki Kobayashi, Masayuki Itoh
International conference on Strongly correlated electron systems 2016
KAKENHI (Grants-in-Aid for Scientific Research) 11
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Study on novel physical properties of quantum materials with multi-orbital electron systems
Grant number：19H01837 2019.4 - 2023.3
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Authorship：Coinvestigator(s)
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Investigation on novel quantum phases appeared between itinerant and localized regions in multi-orbital electron systems
Grant number：16H04012 2016.4 - 2019.3
Itoh Masayuki
Authorship：Coinvestigator(s)
Strongly correlated multi-orbital d electron systems between itinerant and localized regions show novel quantum phenomena due to the multi-orbital effect. In this study we have performed characteristic nuclear magnetic resonace (NMR) experiments such as orbital-resolved NMR to understand the phenomena of the strongly correlated electron systems. We obtained interesting results of electronic phase diagram of a superconducting system, charge order in a one-dimensional conductor, nematic order and fluctuation in iron-based superconductors, electronic states of a spin-crossover material, hidden order in a degenerated electron system, magnetic excitations in a candidate of the Kitaev spin liquid, and high-pressure properties of an excitonic-insulator candidate.
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Observation of local orbital states and their role for the electronic state
Grant number：15K05167 2015.4 - 2018.3
Kobayashi Yoshiaki
Authorship：Principal investigator
Grant amount：\4810000 （ Direct Cost: \3700000 、 Indirect Cost：\1110000 ）
Nematic fluctuation was investigated from 75As nuclear magnetic resonance for the iron based superconductors Ba(Fe1-xCox)2As2, NaFeAs, and LiFeAs. We found that the electric nematic fluctuation obtained from Raman scattering can be monitored from the temperature and x dependence of the in-plane anisotropy (eta) of the electric field gradient at the As nuclear position. The eta for all samples shows Curie-Weiss type temperature dependence, where the fitting parameters, C_eta and T_eta, which correspond to Curie constant and the Weiss temperatures, respectively, systematically have x-dependences. The T_eta’s show roughly ~ Ts-50 (K) in x <0.05 where the nematic order emerges (Ts is nematic ordered temperature). Similarly with the result of Raman scattering, the T_eta becomes zero with x~0.055. At x>0.055, we found that the T_eta’s become negative, suggesting the existence of antiferro-type orbital fluctuation.
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Study on novel physical properties due to competion or cooperation among degrees of freedom in strongly correlated electron systems with multi-orbitals
Grant number：24340080 2012.4 - 2015.3
ITOH Masayuki
Authorship：Coinvestigator(s)
Strongly correlated 3d electron systems have novel physical properties due to the competition or cooperation among degrees of freedom. In this study, we have investigated localized or itinerant electron systems with multi-orbitals located in the vicinity of the metal-insulator transition to clarify the mechanism of the novel physical phenomena. We found rich physics of heavy fermion, orbital order, frustration, Fe-based superconductivity, and so on in the 3d transition metal oxides and compounds.
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Resaerch for Excitonic Insulators
Grant number：16K13835 2016.4 - 2018.3
Itoh Masayuki
Authorship：Coinvestigator(s)
An excitonic insulator is a novel insulator driven by the exciton condensation. We have nuclear magnetic resonance (NMR) measurements to probe the exciton condensation. For a candidate of the excitonic insulator Ta2NiSe5, we observed the characteristic temperature dependences of the Se nuclear spin-lattice relaxation rate and the local magnetic susceptibility coming from the exciton condensation. Thus NMR is concluded to be a useful probe to study the excition condensation in excitonic insulators.
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Origin of non-superconducting phase by which the superconducting phase were divided.
Grant number：20540354 2008 - 2010
KOBAYASHI Yoshiaki
Authorship：Principal investigator
Grant amount：\4550000 （ Direct Cost: \3500000 、 Indirect Cost：\1050000 ）
The superconductivity of the layered cobalt oxides appears in the phase diagram of T-v_Q (or -the lattice parameter c), where the v_Q is Co nuclear electronic quadrupole resonance frequency. In this phase diagram, the non-superconducting (SC) phase appears to divide the SC phase into two regions. To investigate the nature of the non-SC phase, we have measured the T-dependences of various physical properties. The results are consistently understood by the non-SC phase to be not in the magnetic ordered state but in the charge disproportionate state. Although the existences of multi-SC phases and non-SC phase were explained by changing of the relative energy level between a_<1g>-band and e_g'-band of this layered cobalt oxide, we found that the possibility was excluded by those results, for example, the v_Q (or c) dependence of the electronic specific heat coefficient, NMR Knight shift, and the q-dependence of magnetic excitation by neutron scattering measurements. As the non-magnetic impurity does not suppressed the superconductivity, and NMR Knight shift supports the spin-singlet pairing formation, the SC pairing is considered to be formed mainly by electron-phonon interaction, and it is considered that the transition to non-SC phase suppresses the superconductivity though the decreases of the density of states at Fermi level.
Next, we have studied the Fe-based superconductors with ten times as large as T_c for the layered cobalt oxides. Non-magnetic impurity effect on T_c for Fe system was found to be very weak as well as the Co-oxides, indicating that the Fe system is found to give an opportunity to perform comparative studies with the layered cobalt oxides. -
Magnetic Frustration of Spin 1/2 Pyrochlore Compound
Grant number：18540346 2006 - 2007
YASUI Yukio
Authorship：Coinvestigator(s)
The magnetic behavior in the low temperature region and the ground state of the quantum spin system with magnetically frustrated remain open problem theoretically and experimentally. Pyrochlore compound Hg_2Cu_2FeS has Cu^2+ ions with S=1/2, which consists of a 3-dimensional linkage of corner-sharing Gu_4 tetrahedra, and the Weiss temperature θ_w estimated from the temperature (T) dependence of the magnetic susceptibility is〜150 K, indicating the interaction between the Cu^2+ pins is antiferromagnetic. From these facts, this system is regarded as an ideal example of the geometrically frustrated quantum spins systems. The measurements of the magnetic susceptibility and specific heat as well as neutron diffraction studies have been carried out on the polycrystalline samples of Hg_2Cu_2F_6S. No magnetic transition has been observed in the temperature range clown to 2 K, indicating that the magnetic frustration is not released down to the lowest temperature. To extract microscopic information of the magnetic behavior ; we have also carried out ^19F-NMR, Above〜100K the Knight shift roughly obeys the following Curie Weiss law. With decreasing T from〜100K, the Knight shift has a broad maximum at around 80K, and with further decreasing T, the Knight shift decreases significantly. We cannot distinguish if the Knight shift (spin component of the magnetic susceptibility) approaches zero or not, as Tapproaches zero, because of the increase in the width of the NMR spectra. The magnetic correlation length ξ is estimated by comparing the observed spin-lattice relaxation rate divided T,1/ (T_1T) with the theoretical result obtained by Ganals, et. al. for a 1/2 spin system on the pyrochlore lattice. The values of 1/ (T_1T) and increase gradually with decreasing T, and as the temperature is lowered, ξ increases to a value approximately equal to the Cu-Cu atomic distance. It is interesting that these behaviors seem to correspond to the characteristics of spin system with the geometrical frustration. Because the broadening of the NMR spectra induced by the effects of impurities and/or defects is observed in the low temperature region, it is required to be synthesized the higher purity sample. However, it is not easy to see the intrinsic behavior without the disturbance of the extrinsic effects such as lattice defects and/or impurities, because just a small perturbation brings about rather serious efforts on systems with large degeneracy, which steins from their geometrical characteristics.
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Metal-insulator transition near the superconducting phase of two-dimensional cobalt oxides
Grant number：17540323 2005 - 2006
KOBAYASHI Yoshiaki
Authorship：Principal investigator
Grant amount：\3300000 （ Direct Cost: \3300000 ）
We have produced principally three results, which are of considering importance to the mechanism of the formation of the Cooper pairs in Na_xCoO_2・yH_2O superconductors.
(1) We have revealed that the superconducting pairs in the superconducting state of Na_xCoO_2・yH_2O are in the spin-singlet state, by the measurements of the ^<59>Co-NMR Knight shift for both magnetic field (H) directions parallel and perpendicular to the CoO_2planes in the superconducting state using single phase single crystals.
(2) The superconducting transition temperatures T_c of Na_xCoO_2・yH_2O have been found to exhibit the systematic dependence on the ^<59>Co nuclear electric quadrupole resonance frequency ν_Q. In the T-3ν_Q phase diagram, the superconducting region of 3ν_Q, spreading over the region between 〜12.0 and 〜12.9 MHz, is divided into two regions by the non-superconducting phase between 〜12.5 and 〜12.6 MHz.
We have investigated the origin of the non-superconducting phase by detailed experimental measurements of ^<59>Co-NQR and ^2D-NMR and found that the non-superconducting phase is in the charge-density-wave (CDW) or the charge disproportionate state, in which the magnetic moments induced inhomogeneously by this transition become frozen at low temperatures.
(3) We have revealed that the x dependence of the electronic nature of Na_x,CoO_2 which is the parent compound of Na_<0.3>CoO_2・1.3H_2O superconductors. In particular, the successive phase transitions observed in Na_<0.5>CoO_2 at 87 K (T_<c1>) and 53 K (T_<c2>) have been studies. Na_<0.5>CoO_2 indicates the antiferromagnetic ordering below T_<c1>, where we have determined the unusual magnetic structure by ^<59>Co-NMR and neutron diffraction studies.
It has been found from the X dependence of χ-T and 1/T_1-T curves that the two-dimensional nature of the electrons of Na_xCoO_2 is enhanced and the antiferromagnetic correlation increases in this system as the Na concentration x decreases. Therefore, the superconducting pairs are expected to be in the singlet state. This is consistent with the results of the Knight shift studies in Na_<0.3>CoO_2-1.3H_2O. -
Control of the Electronic State of Co Oxides and Studies on Novel Superconductivity
Grant number：16204025 2004 - 2007
SATO Masatoshi
Authorship：Coinvestigator(s)
Many systems with strongly correlated electrons have been synthesized and their physical properties have been studied to find "unusual" or "anomalous" physical properties which are useful for development of novel physical concepts. In the studies, we synthesized materials and characterized them first, and then, studied their macroscopic properties. If they seemed to have physically attractive nature, experimental methods, such as NMR and neutron scattering, were applied to further study it microscopically, where knowledge accumulated in the past two decades in the study of high To Cu oxides were used as the guide line of the works. In the microscopic studies, we often used single crystals prepared by ourselves, which made us possible to obtain quite reliable experimental results. The main subjects on which we could make significant achievements are ; (1) several problems which remained in the studies of high-T, superconductivity of Cu oxides, (2) mechanism of the superconductivity of Na_xCo0_2 yH_2O (y〜3), (3) unusual behavior of the anomalous Hall effect observed in nontrivial magnetic structures such as Nd_2Mo_2O_2 and spin-glass system, (4) spin liquid state of the quantum spins in pyrochlore system Hg_2Cu_2F_6S, (5) control of the spin state of Co ions in perovskite and related systems, (6) a spin gap phenomenon and a new type phase transition found in(pseudo)honeycomb systems, (7) search for multiferroics and detailed studies of multiferroic phenomenon found in systems with CuO_2 ribbons having simple spin 1/2 Cu^2+ chains, and so on. In the studies of these systems, preparation or syntheses of the systems and finding new physical phenomena are closely connected. For the further description of the achievements, we add the following as the examples. In the study of the superconductivity, we have shown that the Cooper pairs are in the singlet state, excluding predictions of many theoretical works as well as results of experimental studies carried out in the same period by other groups. We have presented complete T_c-v_Q phase diagram (v_Q : NMR quadrupole frequency), and also obtained key information on the dynamical magnetic behavior by neutron inelastic scattering of the superconductor. On the controversy if Nd_2Mo_2O_7 is the unique example of systems which exhibit the unusual anomalous Hall effect induced by the spin chirality mechanism, we have excluded such the possibility quite clearly by detailed neutron diffraction studies. To find the realization of the chirality mechanism of the anomalous Hall effect at least in periodic system remains as the future subject Our discovery of the multiferroic system LiVCuO_4 has presented a new attractive example with spin 1/2 quantum spin chains 'with helical structure, which is simple and convenient for the detailed study on the characteristics of the multiferroic behavior
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Metal-insulator transitions induced by pressure for perovskite cobalt oxides
Grant number：15540336 2003 - 2004
KOBAYASHI Yoshiaki
Authorship：Principal investigator
Grant amount：\3700000 （ Direct Cost: \3700000 ）
Cobalt oxides with network of CoO_6 octahedra have attracted interest, because they exhibit various notable physical characteristics. The main subject of this research is the search of the method to control the electronic state of the cobalt oxides. We have studied (1)the mechanisms of the metal-insulator(M-I) transition of the perovskite cobalt oxide Pr_<1-x>Ca_xCoO_3 and (2)the symmetry of the superconducting order parameter of a cobalt oxide superconductor Na_xCoO_<2-y>H_2O.
(1)The structural studies and the magnetic and transport measurements have been carried out on (Pr_<1-y>R_y)_<1-x>Ca_xCoO_3(R=rare earth elements and Y) at ambient pressure and high pressure. The intimate relationship between the local structure around the Co ions and the electronic (or spin) state of Co^<3+> ions has been discussed. We have found that both the Pr and Co atoms are necessary for the occurrence of the M-I transition, which implies that the Pr 4f-O 2pπ hybridization may be relevant to the occurrence of the transition.
(2)Measurements of ^<59>Co-NMR Knight shift K and nuclear magnetic relaxation rate 1/T_1 have been carried out. Studies of the impurity effect on the superconducting transition temperature T_c have also been carried out on Na_xCoO_<2-y>H_2O. For the magnetic field directions, H‖ and ⊥ CoO_2 plane, K decreases below the T_c(H) with decreasing T, indicating that the superconducting electron pairs are in the singlet state. The negligibly small coherence peak of the 1/T_1T-T curve indicates, at first sight, that the superconducting order parameter has a node. However, the small effect of nonmagnetic impurities on T_c cannot simpty be explained by such kinds of anisotropic order parameter. Now, it is important to understand these results consistently. One possible way is, we speculate, to consider effects of quasi-particle broadening in s-wave superconductors because the broadening brings about the negligibly small coherence peak. -
Anomalous Physical Properties of Strongly Correlated Electron System with Frustration and Spin Chirality
Grant number：14340103 2002 - 2003
SATO Masatoshi
Authorship：Coinvestigator(s)
Studies focused mainly on strongly correlated electrons with geometrical frustration have been carried out. (i)Unusual behaviors of the anomalous Hall resistivity(AHR) of ferromagnetic systems with non-trivial magnetic structure have been studied to clarify if the behavior is related to the ordering of spin chirality χ locally defined for three spins S_1, S_2 and S_3 as χ≡S_1(S_2×S_3). Ground states of frustrated spin systems have been studied experimentally for various pyrochiore type oxides. (ii) Superconductivity of Na_xCoO_2・yH_2O has been studied mainly by means of NMR. (iii)We have also studied the physics of high-T_c Cu oxides mainly by studying the characteristics of their magnetic excitation spectra.
To see the origin of unusual behaviors of AHR of Nd_2Mo_2O_7, the magnetic structure has been analyzed as a function of the applied magnetic field Hand the H-dependence of the chirality (or AHR) has been directly calculated from the obtained results. Mo→Ti substitution effects on the behaviors of the AHR has also been studied. The results of these studies clearly indicate that the chiral order mechanism proposed theoretically does not, at least, have a primary role in determining the behavior of the AHR of Nd_2Mo_2O_7. In the study on AHR of a reentrant spin glass system Fe_<1-x>Al_x, it has been shown that the uniform chirality induced by the coupling of the frozen chirality with the uniform magnetization contributes to AHR. In the study on so-called spin ice system, Ho_2Ti_2O_7, we hav.e shown what kind of spin correlation this strongly frustrated spin system has at T→0.
To clarify if the superconductivity of Na_xCoO_2・yH_2O with triangular lattice of CoO_2, The NQR 1/T_1T and the NMR Knight shift K have been measured, where a very small (or no) coherence peak of 1/T_1T and the decrease of K have been observed. Extensive studies are now being carried out.
Teaching Experience (On-campus) 31
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Condensed matter physics III
2015
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Foundations of Electromagnetics I
2015
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Foundations of Electromagnetics II
2016
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Foundations of Electromagnetism I
2022
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[G30] Advanced Solid State Physics 3
2022
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Advanced Solid State Physics 3
2022
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Solid State Physics V
2022
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Science of Materials
2021
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Special Lectures on Condensed Matter Physics and Biophysics
2022
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Special Lectures on Condensed Matter Physics and Biophysics
2022
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Laboratory in Physics
2022
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Special Lectures on Condensed Matter Physics and Biophysics
2021
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Physics Seminars VII-II
2021
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Foundations of Electromagnetics II
2020
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Physics Tutorial I
2020
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Science of Materials
2020
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Special Lectures on Condensed Matter Physics and Biophysics
2020
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電磁気学II
2019
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Foundations of Electromagnetics I
2019
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Special Lectures on Condensed Matter Physics and Biophysics
2019
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Foundations of Electromagnetics II
2018
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Foundations of Electromagnetics II
2017
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Foundations of Electromagnetics I
2017
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Foundations of Electromagnetics I
2016
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物理学演習Ⅳ
2012
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First Year Seminar A
2012
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First Year Seminar A
2011
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物理学実験Ⅱ
2008
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物理学実験Ⅰ
2008
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総合演習
2007
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物理学実験
2007
Teaching Experience (Off-campus) 1
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物理学特論IV
2019.8 （Niigata University）
Social Contribution 3
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日本物理学会Jrセッション審査委員
Role(s)：Organizing member
日本物理学会 日本物理学会Jrセッション 日本物理学会2023年年会 2022.4 - 2023.3
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日本物理学会Jrセッション審査委員
Role(s)：Investigater
日本物理学会 2021.4 - 2022.3
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日本物理学会第75回年次大会(2020年)運営委員
Role(s)：Organizing member
一般社団法人 日本物理学会 2020.3