Faculty Profiles - KOBAYASHI, Yoshiaki

Papers - KOBAYASHI, Yoshiaki

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Site-selective observation of spin dynamics of a Tomonaga-Luttinger liquid in frustrated Heisenberg chains Reviewed

Nguyen, Diep Minh and Temurjonov, Azimjon A. and Hirai, Daigorou and Hiroi, Zenji and Janson, Oleg and Yasuoka, Hiroshi and Matsushita, Taku and Kobayashi, Yoshiaki and Shimizu, Yasuhiro

Physical Review B Vol. 111 ( 6 ) page： 064423-1 - 064423-11 2025.2

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

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

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

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

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

Poisoning effect of Mn in LaFe1-xMnxAsO0.89F0.11: Unveiling a quantum critical point in the phase diagram of iron-based superconductors

Hammerath, F; Bonfà, P; Sanna, S; Prando, G; De Renzi, R; Kobayashi, Y; Sato, M; Carretta, P

PHYSICAL REVIEW B Vol. 89 ( 13 ) 2014.4

Phase separation of antiferromagnetism and superconductivity in Rb x Fe2-y Se2 observed by using Rb NMR

Kobayashi, Y; Saiki, S; Kototani, S; Itoh, M; Sato, M

JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 63 ( 3 ) page： 448 - 452 2013.8

On the superconducting symmetry of Fe-based systems - Impurity effect studies and neutron scattering measurements

Sato, M; Kobayashi, Y; Kawamata, T; Yasui, Y; Suzuki, K; Itoh, M; Kajimoto, R; Ikeuchi, K; Arai, M; Bourges, P

JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. 62 ( 12 ) page： 1726 - 1733 2013.7

Onset of magnetism in optimally electron-doped LFe1-xRuxAsO1-yFy (L = La, Nd, or Sm) superconductors around x=1/4

Sanna, S; Carretta, P; De Renzi, R; Prando, G; Bonfà, P; Mazzani, M; Lamura, G; Shiroka, T; Kobayashi, Y; Sato, M

PHYSICAL REVIEW B Vol. 87 ( 13 ) 2013.4

On the superconducting pairing mechanism of Fe-based systems-Is it new or well-known ?

Sato, M; Kobayashi, Y

SOLID STATE COMMUNICATIONS Vol. 152 ( 8 ) page： 688 - 694 2012.4

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

Study of Ni-Doping Effect of Specific Heat and Transport Properties for LaFe1-yNiyAsO0.89F0.11

Kawamata, T; Satomi, E; Kobayashi, Y; Itoh, M; Sato, M

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 80 ( 8 ) 2011.8

On the Magnetic Excitation Spectra of Ba(Fe0.9Co0.1)2As2 in the Superconducting State

Sato, M; Tatematsu, S; Yasui, Y; Kobayashi, Y; Moyoshi, T; Motoya, K; Kakurai, K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 80 2011.1

Successive magnetic transitions of the kagome staircase compound Co3V2O8 studied in various magnetic fields

Yasui, Y; Kobayashi, Y; Soda, M; Moyoshi, T; Sato, M; Igawa, N; Kakurai, K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 76 ( 3 ) 2007.3

Structural studies of the pyrochlore-related spin-1/2 system Ag2Cu2O3

Uematsu, D; Soda, M; Kobayashi, Y; Sato, M; Igawa, N; Kakurai, K

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： E387 - E388 2007.3

Studies of magnetic behavior of spin-1/2 frustrated system Hg2Cu2F6S

Kawabata, S; Yasui, Y; Kobayashi, Y; Sato, M; Igawa, N; Kakurai, K

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 1295 - 1296 2007.3

Observation of the in-plane ordering of D2O molecules in NaxCoO2 • yD2O by neutron diffraction

Moyoshi, T; Yasui, Y; Soda, M; Kobayashi, Y; Sato, M; Kakurai, K

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Vol. 310 ( 2 ) page： 654 - 656 2007.3

Transport and magnetic studies on the spin state transition of Pr1-xCaxCoO3 up to high pressure

Fujita, T; Miyashita, T; Yasui, Y; Kobayashi, Y; Sato, M; Nishibori, E; Sakata, M; Shimojo, Y; Igawa, N; Ishii, Y; Kakurai, K; Adachi, T; Ohishi, Y; Takata, M

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 73 ( 7 ) page： 1987 - 1997 2004.7

Magnetic structure of Cu0.3Zn0.7Cr2Se4

Iikubo, S; Ohno, Y; Kobayashi, Y; Yasui, Y; Ito, M; Soda, M; Sato, M; Kakurai, K

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 73 ( 4 ) page： 1023 - 1030 2004.4

Study on pseudo gap formation in Cu-oxides at high temperatures

Sato, M; Harashina, H; Takeda, J; Yoshii, S; Kobayashi, Y; Kakurai, K

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 62 ( 1-2 ) page： 7 - 13 2001.1

Pseudo gap formation and related phenomena in Cu-oxides and other systems

Sato, M; Harashina, H; Kobayashi, Y; Kodama, K; Takeda, J; Ueda, E; Shamoto, S; Kakurai, K; Nishi, M

JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Vol. 60 ( 8-9 ) page： 1013 - 1017 1999.8

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have made 53Cr NMR measurements on polycrystalline and single-crystalline film samples to study the local electronic state of a half-metallic ferromagnet CrO2 which has the rutile structure with one crystallographically equivalent Cr site. We observe two kinds of
53Cr NMR spectra in the ferromagnetic state of both the samples. An analysis on the hyperfine field shows the presence of two Cr sites with different orbital occupancies, suggesting that a local orbital order takes place with breaking the local symmetry in the rutile structure. This may be ascribed to the negative charge transfer between chromium and oxygen ions.

DOI： 10.1103/PhysRevB.93.235129

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

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

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

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

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

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

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

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

Spin disorder in an Ising honeycomb chain cobaltate

Igarashi Hirokazu, Shimizu Yasuhiro, Kobayashi Yoshiaki, Itoh Masayuki

PHYSICAL REVIEW B Vol. 89 ( 5 ) 2014.2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Crystal Structure of New Pt-Doped Fe Pnictide Superconductors Reviewed

Vol. 80 page： 073710-(1-3) 2011

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

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

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

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

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

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

⁷⁵As-NMR Studies of LaFeAsO_1-xF_x 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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Results of ⁷⁵As NMR and NQR measurements are reported for superconducting samples of LaFeAsO_1-xF_Rx with various x values. The x dependent widths of the superconducting transition and those of the NQR spectra indicate that the optimally doped LaFeAsO_1-xF_x sample with the superconducting transition temperature T_c=28 K has the smallest width or smallest inhomogeneity of the superconducting order parameter Δ. In the analyses of the temperature (T) dependence of the NMR longitudinal relaxation rate 1/T₁, we have tried to use a simple relation 1/T₁~Tⁿ to see how fast 1/T₁ decreases when the superconducting order parameter grows. The relation holds rather well in the T region of ~0.3T_c<T=<T_c, and n varies from 2.5-6 with varying x, having the maximum value 5-6 at the optimal x. These results indicate that the x dependence of n originates from the spatial distribution of Δ, and that the T^5-6 behavior is considered to be intrinsic to this system.

DOI： 10.1143/JPSJ.79.093709

Superconducting Transition Temperatures and Transport Properties of LaFe1-yRuyAsO0.89F0.11 and LaFeAsO0.89-xF0.11+x Reviewed

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

Language：English Publishing type：Research paper (scientific journal)

The transport behaviors and superconducting transition temperatures Tc of the title systems have been experimentally studied for various x and y values. Together with results reported previously by our group, data are now available for many sets of samples of RFe1-yMyAsO0.89F0.11 with R = La and Nd and M = Co, Mn and Ru and for RFeAsO0.89-xF0.11+x. Dopings of Co and Mn atoms introduce electrons and holes into the FeAs planes, respectively. They also introduce, more or less, randomness effects. Ru atoms introduce scattering centers within the FeAs planes without changing the number of carrier electrons or holes. In contrast, F atoms introduce electron carriers, but not randomness effects or scattering centers into the FeAs planes. From these studies, we can conclude that there are two appreciable mechanisms of Tc suppression by the dopings. The disappearance of or reduction in the area of the hole Fermi surfaces around the Γ point in the reciprocal space has been clearly shown as one of the mechanisms, irrespective of whether or not doped atoms are within the conducting planes. The other mechanism is the electron localization observed for the Mn doping. The rates of the Tc suppression due to the scattering by nonmagnetic Ru and Co atoms have been found to be negligible compared with that expected from the pair breaking theory, indicating that the systems do not have the S± symmetry of the superconducting order parameter.

DOI： 10.1143/JPSJ.79.094702

Web of Science

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

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

Effects of Ru Doping on the Transport Behavior and Superconducting Transition Temperature of NdFeAsO_0.89F_0.11 Reviewed

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

Language：English Publishing type：Research paper (scientific journal)

The transport behavior and superconducting transition temperature T_c of NdFe_1-yRu_yAsO_0.89F_0.11 have been studied for various y values. Because Ru impurities are isoelectronic to host Fe atoms, we basically expect that the number of electrons does not change with y, at least in the region of small y values. The results indicate that the rate of T_c suppression by Ru atoms is too small to be explained by the pair breaking effect of nonmagnetic impurities expected for the S± symmetry, confirming our previous results for Co doping.

DOI： 10.1143/JPSJ.79.023702

Web of Science

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

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

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 2009.12

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Measurements of the electrical resistivity rho, Hall coefficient RH, thermoelectric power S, and the electronic specific heat coefficient gamma have been carried out for samples of LnFe1-yMyAsO1-xFx (Ln=La, Nd; M=Co, Mn; x=0.11) obtained by doping M atoms into the superconducting LnFeAsO1-xFx (Ln 1111) system. The NMR longitudinal relaxation rate 1/T1 has also been measured for samples of LaFe1-yCoyAsO1-xFx with various x values. Co atoms doped into the superconducting LnFeAsO1-xFx are nonmagnetic, and the rate of Tc-suppression absolute value of dTc/dx by Co atoms has been found to be too small to be explained by the pair-breaking effect expected for the S+- superconducting symmetry proposed as the most probable symmetry for the system. This result throws a serious doubt on whether the symmetry is realized in the system. Instead of the pair breaking, two mechanisms of Tc suppression by the doped impurities have been found: One is the electron localization, which appears when the sheet resistance r/sheet exceeds h/4e2=6.45 k-ohme, and the other is the disappearance (or reduction in the area) of the hole Fermi surfaces around the Gamma point in the reciprocal space. The latter mechanism has been observed when the number of electrons increases with increasing Co doping level and the system changes from an anomalous metal to an ordinary one. Regarding the two distinct T dependences of the NMR longitudinal relaxation rate 1/T₁ of LaFeAsO_1-xF_x, we discuss the origin of such a difference, and show that, at least, the T^2.5-3.0-like dependence of 1/T₁ cannot be considered as the experimental evidence for the S+- symmetry of Delta.

DOI： 10.1143/JPSJ.79.014719/

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

*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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Neutron diffraction and 7Li-NMR have been applied to determine the three dimensional magnetic structures of the multiferroic system LiCu2O2, which has four chains (ribbon chains) of edge-sharing CuO4 square planes in a unit cell. First, we have confirmed that there are successive magnetic transitions at TN1 = 24.5 K and TN2 = 22.8 K. In the T region between TN1 and TN2, the quasi one-dimensional spins (S = 1/2) of Cu2+ ions within a chain have a collinear and sinusoidally modulated structure with Cu-moments parallel to the c-axis and with the modulation vector along the b-axis. At T < TN2, an ellipsoidal helical spin structure with the incommensurate modulation has been found. We present detailed parameters, describing the modulation amplitudes, helical axis vectors as well as the relative phases of the modulations of four ribbon chains, which can well reproduce both the NMR and neutron results, in the two magnetically ordered phases. This finding of the rather precise magnetic structures enables us to discuss the relationship between the magnetic structure and the multiferroic nature of the present system in zero magnetic field, as presented in our companion paper (paper I), and open a way how to understand the reported electric polarization under the finite magnetic field.

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

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

*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

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

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

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

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

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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have prepared the superconducting system LaFe1-yCoyAsO1-xFx (x=0.11) and carried out measurements of their electrical resistivity ρ and superconducting diamagnetism. 75As- and 135La-NMR studies have also been carried out. The Knight shift observed for 75As has been found to be suppressed by the superconductivity; for 135La, the shift is almost insensitive to the superconductivity. This result presents rather strong experimental evidence for singlet pairing. The Co doping effect on the superconducting transition temperature Tc is not so significant as expected for superconductors with nodes, suggesting that the potential scattering does not seem to primarily suppress the superconductivity. Even for superconductors without nodes, it may not be so trivial to expect this small effect, if there are two different (disconnected) Fermi surfaces whose order parameters have opposite signs. As a possible explanation of the observed Tc suppression, which is found to be small, seems to be related with the loss of the itinerant nature of the electrons.

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

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

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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

LaFe1-yCoyAsO1-xFx (x=0.11) with various y values were prepared and their electrical resistivities, superconducting diamagnetisms and Hall coefficients have been measured. 75As- and 135La-NMR studies have also been carried out In spite of the successful Co-doping, we have not found any meaningful correlation of Tc with y, which indicates that the Tc-suppression by Co-doping is considered not to be so significant as expected for superconductors with nodes. Even for superconductors without nodes, it may not be easy to expect this small effect on Tc, if there are two different (disconnected) Fermi surfaces whose order parameters have opposite signs. The data of the NMR Knight shift indicate that the Cooper pairs are in the singlet state and the spin susceptibility is almost fully suppressed at low temperature.

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

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

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

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

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

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

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

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

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

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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The superconducting transition temperatures Tc of NaxCoO2.yH2O prepared by various methods have been found to exhibit the systematic dependence on the nuclear quadrupole frequency nQ. In the Tc-3nQ Phase Diagram, the superconducting region is divied into two regions by the nonsuperconducting phase. We have investigated the origin of the nonsuperconducting phase by NMR measurements, the results indicate that the nonsuperconducting phase is possibly in the charge disproportionate state.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

*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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

*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

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Layered Co oxide NaxCoO2·yH2O with the superconducting transition temperature Tc=4.5 K has been studied by 59Co-NMR. The Knight shift K estimated from the observed spectra of a powder sample exhibits almost temperature (T)-independent behavior above Tc and decreases with decreasing T below Tc. This result and the existence of the coherence peak in the spin–lattice relaxation rate versus T curve reported by the present authors indicate, naively speaking, that the singlet order parameter with s-wave symmetry is realized in NaxCoO2·yH2O. Differences in the observed behaviors between the spectra of a nonaligned sample and those of an aligned sample embedded in epoxy adhesive by applying an external magnetic field are discussed.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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