Faculty Profiles - YOKOYA Takayoshi

MISC - YOKOYA Takayoshi

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6a-W-8 Angle-resolved photoemission study of Sr_<14-x>Ca_xCu<24>O_<41> : x-dependence

Sato T., Yokoya T., Takahashi T., Goshima J., Fujino Y., Nagata T., Uehara M., Akimitsu J.

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 628 - 628 1997.9

7a-W-6 Angle-resolved photoemission study of one dimensional cuprate Sr_2CuO_3

Fujisawa H, Yokoya T, Takahashi T, Miyasaka S, Kifune M, Takagi H

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 662 - 662 1997.9

5p-YF-6 Normal-state gap studied by angle-resolved photoemission spectroscopy

Yokoya T., Takahashi T.

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 610 - 610 1997.9

7p-T-4 Normal-state gap of Pb-substituted Bi2201 studied by high-resolution angle-resolved photoemission spectroscopy

Yokoya T, Ding H, Takeuchi T, Campuzano J.C., Takahashi T, Chong I, Terashima T, Takano M

Meeting abstracts of the Physical Society of Japan 52 ( 2 ) 673 - 673 1997.9

28p-PSA-40 Resonant Photoemission Study of CeTiO_<3+y> and Ce_<1-x>Sr_xTiO_3

Akaki O., Fujisawa H., Ashihara A., Yokoya T., Chainani A., Takahashi T., Onoda M.

Meeting abstracts of the Physical Society of Japan 52 ( 1 ) 454 - 454 1997.3

30p-G-3 Metallic-Covalent Bonding Conversion in Icosahedral Cluster Solids

Kimura K, Matsuda H, Fujimori M, Terauchi M, Tanaka M, Kumigashira H, Yokoya N, Takahashi T

Meeting abstracts of the Physical Society of Japan 52 ( 1 ) 168 - 168 1997.3

Angle-resolved photoemission spectroscopy of non-cuprate two-dimensional perovskite superconductor Sr2RuO4

T. Yokoya, A. Chainani, T. Takahashi, H. Ding, J. C. Campuzano, M. Kasai, Y. Tokura

Physica B: Condensed Matter 237-238 377 - 379 1997

Language：English Publisher：Elsevier

We have performed high-resolution angle-resolved photoemission spectroscopy on single crystal Sr2RuO4. at low temperature. We observed that the dispersion of energy bands near the Fermi level (EF) is about two times smaller than the band calculation. One band forms an extended van-Hove singularity (vHs) near EF around the midpoint between F and Z point like in cuprate superconductors, regardless of the character of electronic states near EF. The observed Fermi surface topology (one electron-like Fermi surface sheet centered at Γ point and two hole-like ones centered at X point) is qualitatively different from the calculated Fermi surface topology (two electron-like fermi sheets centered at Γ point and one hole-like one centered at X point), though the observed total electron count seems to be conserved. These results suggest that the extended vHs may be a general electronic structure of correlated two-dimensional metals and the correlation effect may change the Fermi surface topology as well as the band dispersion.

DOI： 10.1016/S0921-4526(97)00237-8

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High-resolution angle-resolved photoemission study of Sr14-xCaxCu24O41 (x=0 and 6)

T. Yokoya, H. D. Kim, A. Ashihara, H. Kumigashira, H. Fujisawa, T. Takahashi, M. Uehara, T. Nagata, J. Akimitsu

Physica C: Superconductivity and its Applications 282-287 ( 2 ) 997 - 998 1997

Language：English Publisher：Elsevier

We have performed high-resolution angle-resolved photoemission spectroscopy (ARPES) of ladder compounds Sr14-xCaxCu24O41 (x = 0 and 6) to study the change of the electronic structure near the Fermi level (Ep) by substitution of Sr with Ca. The experimental band structures of both compounds determined by ARPES show a dispersive band near EF, which has a minimum binding energy at ka = (2n+1)π/2 (n=0, ±1, ±2...) with the periodicity of a ladder sublattice. This result indicates that the electronic states near EF originate in the ladder and form aMott-Hubbard band with an energy gap at ka= (2n+1)π/2. This suggests that Cu atoms in the ladder take essentially a divalent state (Cu2+) and "self-doped" holes reside on the chain. It was also found that the dispersive band of Sr8Ca6Cu24O41 is closer to EF than that of Sr14Cu24O41, indicating that the ladder band is "doped" with holes by Ca-substitution. This suggests that the superconductivity observed in a heavily Ca-substituted sample occurs on the ladder.

DOI： 10.1016/S0921-4534(97)00632-1

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Doping dependence of Fermi surface in BI2212: angle-resolved photoemission spectroscopy.

横谷尚睦, DING H, 竹内恒博, CAMPUZANO J C, RANDERIA M, NORMAN M R, 茂筑高士, 門脇和男, 高橋隆

日本物理学会講演概要集(年会) 52 ( 1 Pt 3 ) 1997

Sr_xCa_<14-x>Cu_<24>O_<41>角度分解光電子分光 : ドーピング依存性(第42回物性若手夏の学校(1997年度))

佐藤宇史, 横谷尚睦, 高橋隆, 五嶋潤治, 藤野裕一, 永田貴志, 上原政智, 秋光純

物性研究 69 ( 3 ) 574 - 574 1997

Angle-resolved photoemission study of one dimensional cuprate Sr_2CuO_3

Fujisawa H., Yokoya T., Takahashi T., Miyasaka S., Kifune M., Takagi H.

69 ( 3 ) 574 - 574 1997

High-Resolution Angle Resolved Photoemission Study of CeSb

Kumigashira H., Kim H.D., Ashihara A., Chainani A., Yokoya T., Takahashi T., Uesawa A., Suzuki T.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 2 ) 283 - 283 1996.9

Paramagnetic-to-Antiferroparamagnetic Phase Transition of CeSb Studied by High-Resolution Angle Resolved Photoemission

Kumigashira H., Kim H.-D., Ashihara A., Chainani A., Yokoya T., Takahashi T., Uesawa A., Suzuki T.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 3 ) 13 - 13 1996.9

Fermi surface of Sr_2RuO_4 : high-resolution photoemission spectroscopy

Yokoya T., H Ding, A Chainani, Takahashi T., J.C Campuzano, Kasai M., Tokura Y.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 3 ) 425 - 425 1996.9

High-resolution photoemission study of normal-state gap in underdoped Bi2212

Yokoya T., H Ding, Takahashi T., J.C Campuzano, M Randeria, M.R Norman, Mochiku T., Kadowaki K., J Giapintzakis

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 3 ) 550 - 550 1996.9

High-resolution Angle-Resolved Photoemission Study of LaSb

Ashihara A., Kumigashira H., Kim H.D., Chainani A., Yokoya T., Takahashi T., Uesawa A., Suzuki T.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 2 ) 282 - 282 1996.9

Angle-resolved phtoemission study of SrCuO_2;Spin-Charge Separation?

Takahashi T., Yokoya T., Fujisawa H., Tanaka M., Takei F.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 3 ) 487 - 487 1996.9

Photoemission Study of Ladder Compound Sr_<14-x>Ca_xCu_<24>O_<41>

Takahashi T., Yokoya T., Akaki O., Fujisawa H., Ashihara A., A Chainani, Uehara M., Nagata T., Akimitsu J.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 3 ) 483 - 483 1996.9

Normal-state gap in Bi_2Sr_2CaCu_2O_8 observed by high-resolution photoemission spectroscopy

Yokoya T., Ding H., Takahashi T., Campuzano J.C., Randeria M., Norman M.R., Mochiku T., Kadowaki K., Giapintzakis J.

Abstracts of the meeting of the Physical Society of Japan. Sectional meeting 1996 ( 2 ) 259 - 259 1996.9

3P-YF-9 High-Resolution Angle Resolved Photoemission Study of CeP

Kumigashira H., Yang S.-H., Yokoya T., Chainani A., Takahashi T., Uesawa A., Suzuki T.

Abstracts of the meeting of the Physical Society of Japan. Annual meeting 51 ( 3 ) 250 - 250 1996.3

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