超高分解能角度分解光電子分光装置の建設と水和コバルト酸化物超伝導機構の研究

• 研究課題/領域番号: 17684017
• 研究種目: 若手研究(A)
• 配分区分: 補助金
• 研究分野: 物性Ⅱ
• 研究機関: 東北大学
• 研究代表者: 佐藤 宇史 東北大学, 大学院・理学研究科, 助教 (10361065)
• 研究期間 (年度): 2005 – 2007
• 研究課題ステータス: 完了 (2007年度)
• 配分額: 29,640千円 (直接経費: 22,800千円、間接経費: 6,840千円); 2007年度: 4,680千円 (直接経費: 3,600千円、間接経費: 1,080千円); 2006年度: 8,320千円 (直接経費: 6,400千円、間接経費: 1,920千円); 2005年度: 16,640千円 (直接経費: 12,800千円、間接経費: 3,840千円)
• キーワード: 光電子分光 / 超伝導 / 遷移金属酸化物

研究概要

水和コバルト酸化物超伝導体の超伝導発現機構を解明する目的で、高分解能光電子分光装置の建設・改良を行った。本装置および高輝度放射光施設を用いて、Na_<0.5>CoO_2における金属-絶縁体転移の起源を明らかにするために、高分解能角度分解光電子分光の精密な運動量および温度依存性の測定を行った。その結果、絶縁相においてエネルギーギャップを観測する事に成功し、そのギャップが強く波数に依存性して異方的である事を見出した。また、温度変化測定の結果、金属-絶縁体転移温度である50Kよりも遥かに高温からギャップが形成されていることがわかった。これらの実験結果から、エネルギーギャップの形成には磁性転移が密接に関係していると結論した。また、K(H)点におけるeg'フェルミ面の欠如がバルクの電子状態に普遍的なものかどうかを明らかにするために、低エネルギー光を用いた高分解能光電子分光を行った結果、20-100eVの紫外線を用いた実験と同様にeg'バンドはフェルミ準位に到達せず、K(H)点近傍のフェルミ面は存在しない事を明らかにした。さらに、コバルト酸化物の研究比較として、銅酸化物La系超伝導体の高分解能光電子分光測定を行った。その結果、超伝導状態におけるエネルギーギャップの測定に成功し、ギャップ形状が理論的に予想されるd_<x^2-y^2>波対称性から大きく逸脱していることを明らかにした。さらに、超伝導転移温度よりも上の温度において擬ギャップを観測し、その波数依存性が超伝導状態におけるアンチノードのエネルギーギャップと類似している事を見出した。これらの事から、擬ギャップと超伝導ギャップが密接に関係していると結論した。

研究成果

• [雑誌論文] Effect of Zn impurities on the electronic structure of La_<1.85>Sr_<0.15>CuO_4 studied by high-resolution angle-resolved photoemission spectroscopy (2008)
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  • 雑誌名: Physical Review B 77
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• [雑誌論文] Low-energy excitations in graphite studied by ultrahigh-resolution angle-resolved photoemission spectroscopy (2008)
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  • 雑誌名: Physica B (In press)
  • 査読あり
• [雑誌論文] Many-body interactions in hole-doped high-T_c cuprates studied by high-resolution ARPES (2008)
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• [雑誌論文] Quasiparticle lifetime in graphite studied by ultra-high resolution ARPES (2008)
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  • 雑誌名: J. Phys. Chem. Solids (In press)
  • 査読あり
• [雑誌論文] High-resolution angle-resolved photoemission study of bulk electronic states in YBa_2Cu_3O_<7-δ> (2008)
  • 著者名/発表者名: K. Nakayama, et. al.
  • 雑誌名: J. Phys. Chem. Solids (In press)
  • 査読あり
• [雑誌論文] Universal character of CoO_2 plane studied by high-resolution angle-resolved photoemission (2008)
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  • 雑誌名: Physica B (In press)
  • 査読あり
• [雑誌論文] Band structure and Fermi surface of heavy Fermion compounds Ce_2Tin_8 (T=Co, Rh, In) studied by angle-resolved photoemission spectroscopy (2008)
  • 著者名/発表者名: S. Souma, et. al.
  • 雑誌名: Physica B (In press)
  • 査読あり
• [雑誌論文] Doping induced evolution of Fermi surface in low carrier superconductor Tl-doped PbTe (2008)
  • 著者名/発表者名: K. Nakayama, et. al.
  • 雑誌名: Physical Review Letters (In press)
  • 査読あり
• [雑誌論文] Anomalous momentum dependence of the superconducting coherence peak an its relation to the pseudogap in La_<1.85>Sr_<0.15>CuO_4 (2007)
  • 著者名/発表者名: K. Terashima, et. al.
  • 雑誌名: Physical Review Letters 99
  • 査読あり
• [雑誌論文] Universality of low-energy mass renormalization in the superconducting state of hole-doped high-Tc superconductors (2007)
  • 著者名/発表者名: T. Sato, et. al.
  • 雑誌名: J. Phys. Soc. Jpn 76
  • NAID: 130005296506
  • 査読あり
• [雑誌論文] Electronic structure of sodium tungsten bronzes Na_x WO_3 by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: S. Raj, et. al.
  • 雑誌名: Physical Review B 75
  • 査読あり
• [雑誌論文] Evolution of the pseudogap across the magnet-superconductor phase boundary of Nd_<2-x>Ce_xCuO_4 (2007)
  • 著者名/発表者名: H. Matsui, et. al.
  • 雑誌名: Physical Review B 75
  • 査読あり
• [雑誌論文] Electronic structure of quasi-one-dimensional conductors Nb_3Xc_4 (X_c=S, Se, Te) studied by angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T. Dobashi, et. al.
  • 雑誌名: Physical Review B 75
  • 査読あり
• [雑誌論文] Anomalous superconducting-gap symmetry of noncentrosymmetric La_2C_3 observed by ultrahigh-resolution photoemission spectroscopy (2007)
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  • 雑誌名: Physical Review B 76
  • 査読あり
• [雑誌論文] Anisotropic spin-orbit interaction in Sb (111) surface studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K. Sugawara, et. al.
  • 雑誌名: J. Magn. Magn. Matt. 310 ページ: 2177-2179
  • 査読あり
• [雑誌論文] Metal-insulator transition in sodium tungsten bronzes, Na_xWO_3, studied by angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: S. Raj, et. al.
  • 雑誌名: J. Magn. Magn. Matt. 310
  • 査読あり
• [雑誌論文] Bogoliubov quasiparticle and low-energy dispersion kink in the superconducting state of La_<1.85>Sr_<0.15>CuO_4 (2007)
  • 著者名/発表者名: T. Sato, et. al.
  • 雑誌名: Physica C 460-462 ページ: 864-865
  • 査読あり
• [雑誌論文] Photoemission study of the superconducting-gap symmetry in electron-doped high-T_c superconductors (2007)
  • 著者名/発表者名: H. Matsui, et. al.
  • 雑誌名: Physica C 460-462 ページ: 862-863
  • 査読あり
• [雑誌論文] Origin of shadow bands in single-layered Bi_2Sr_2CuO_<6+d> studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K. Nakayama, et. al.
  • 雑誌名: Physica C 460-462 ページ: 931-933
  • 査読あり
• [雑誌論文] Electronic structure of LaAgSb_2 and CeAgSb_2 studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T. Arakane, et. al.
  • 雑誌名: J. Magn. Magn. Matt. 310 ページ: 396-397
  • 査読あり
• [雑誌論文] Origin of shadow bands in high-T_c cuprate superconductors studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K. Nakayama, et. al.
  • 雑誌名: Physica C 463-465 ページ: 48-51
  • 査読あり
• [雑誌論文] Single-particle excitation gap in La_<2-x> Sr_xCuO_4 studied by high-resolution angle-resolved photoemission (2007)
  • 著者名/発表者名: Y. X. Xiao, et. al.
  • 雑誌名: Physica C 463-465 ページ: 44-47
  • 査読あり
• [雑誌論文] Electronic structure of M_xCoO_2 (M: Na, K, and Rb) studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T. Arakane, et. al.
  • 雑誌名: Physica C 463-465 ページ: 149-151
  • 査読あり
• [雑誌論文] Magnetic isotope effect in Bi_2Sr_2CaCu_2O_<8+δ> studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K. Terashima, et. al.
  • 雑誌名: Physica C 460-462 ページ: 934-936
  • 査読あり
• [雑誌論文] Bulk and surface low-energy excitations in YBa_2Cu_3O_<7-d> studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: N.Nakayama et al.
  • 雑誌名: Physical Review B 75 ページ: 14513-14513
• [雑誌論文] Electronic structure of M_XCoO_2 (M : Na, K, and Rb) studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T.Arakane et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Many-body interactions in Bi-based high-T_c cuprates studied by angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: J. Phys. Chem. Solids (In press)
• [雑誌論文] Metal-insulator transition in sodium tungsten bronzes, Na_xWO_3, studied by angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: S.Raj et al.
  • 雑誌名: J. Magn. Magn. Matter (In press)
• [雑誌論文] Bogoliubov quasiparticle and low-energy dispersion kink in the superconducting state of La_<1.85>Sr_<0.15>CuO_4 (2007)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Photoemission study of the superconducting-gap symmetry in electron-doped high-T_c superconductors (2007)
  • 著者名/発表者名: H.Matsui et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Origin of shadow bands in single-layered Bi_2Sr_2CuO_<6+d> studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K.Nakayama et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Electronic structure of LaAgSb_2 and CeAgSb_2 studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T.Arakane et al.
  • 雑誌名: J. Magn. Magn. Metter (In press)
• [雑誌論文] Origin of shadow bands in high-T_c cuprate superconductors studied by high-resolution angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: K.Nakayama et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Single-particle excitation gap in La_<2-x>Sr_xCuO_4 studied by high-resolution angle-resolved photoemission (2007)
  • 著者名/発表者名: Y.X.Xiao et al.
  • 雑誌名: Physica C (In press)
• [雑誌論文] Fermi surface and band dispersions of M_xCoO_2 (M : Na, K, and Rb) studied by angle-resolved photoemission spectroscopy (2007)
  • 著者名/発表者名: T.Arakane et al.
  • 雑誌名: J. Phys. Soc. Jpn. (In press)
• [雑誌論文] Angle-Resolved Photoemission Spectroscopy of the Insulating Na_xWO_3 : Anderson Localization, Polaron Formation, and Remnant Fermi Surface (2006)
  • 著者名/発表者名: S.Raj et al.
  • 雑誌名: Physical Review Letters 96 ページ: 1476031-1476031
• [雑誌論文] Shadow bands in single-layered Bi_2Sr_2CuO_<6+δ>studied by angle-resolved photoemission spectroscopy (2006)
  • 著者名/発表者名: N.Nakayama et al.
  • 雑誌名: Physical Review B 74 ページ: 54505-54505
• [雑誌論文] From Fermi Arcs to nodal metal : scaling of the pseudogap with temperature and doping (2006)
  • 著者名/発表者名: A.Kanigel et al.
  • 雑誌名: Nature Physics 2 ページ: 447-447
• [雑誌論文] Impurity effects on electron-mode coupling in high-temperature superconductors (2006)
  • 著者名/発表者名: K.Terashima et al.
  • 雑誌名: Nature Physics 2 ページ: 27-31
• [雑誌論文] Fermi surface and edge-localized state in graphite studied by high-resolution angle-resolved photoemission spectroscopy (2006)
  • 著者名/発表者名: K.Sugawara et al.
  • 雑誌名: Physical Review B 73
• [雑誌論文] Fermi Surface and Anisotropic Spin-Orbit coupling in Sb(111) studied by Angle-Resolved Photoemission Spectroscopy (2006)
  • 著者名/発表者名: K.Sugawara et al.
  • 雑誌名: Physical Review Letters 96
• [雑誌論文] Electronic structure of impurity-substituted Bi_2Sr_2CaCu_2O_<8+δ> studied by angle-resolved photoemission spectroscopy (2006)
  • 著者名/発表者名: K.Terashima et al.
  • 雑誌名: J.Phys.Chem.Solids (in press)
• [雑誌論文] ARPES study of quasiparticle state in electron-doped cuprate Nd_<2-x>Ce_xCuO_4 (2006)
  • 著者名/発表者名: H.Matsui et al.
  • 雑誌名: J.Phys.Chem.Solids (in press)
• [雑誌論文] Many-body interactions in Bi-based high-T_c cuprates studied by angle-resolved photoemission spectroscopy (2006)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: J.Phys.Chem.Solids (in press)
• [雑誌論文] Fermi surface evolution and Luttinger theorem in Na_xCoO_2: a systematic photoemission study (2005)
  • 著者名/発表者名: H.-B.Yang et al.
  • 雑誌名: Physical Review Letters 95
• [雑誌論文] Angle-Resolved Photoemission Spectroscopy of the Antiferromagnetic Superconductor Nd_<1.87>Ce_<0.13>CuO_4: Anisotropic Spin-Correlation Gap, Pseudogap, and the Induced Quasiparticle Mass Enhancement (2005)
  • 著者名/発表者名: H.Matsui et al.
  • 雑誌名: Physical Review Letters 94
• [雑誌論文] High-resolution ARPES study of quasiparticles in high-T_c superconductors (2005)
  • 著者名/発表者名: T.Takahashi et al.
  • 雑誌名: New Journal of Physics 7
• [雑誌論文] Angle-resolved and resonant photoemission spectroscopy on heavy-fermion superconductors Ce_2CoIn_8 and Ce_2RhIn_8 (2005)
  • 著者名/発表者名: S.Raj et al.
  • 雑誌名: Physical Review B 71
• [雑誌論文] Angle-resolved photoemission spectroscopy on metallic sodium tungsten bronzes Na_xWO_3 (2005)
  • 著者名/発表者名: S.Raj et al.
  • 雑誌名: Physical Review B 72
• [雑誌論文] Electronic structure of η-Mo_4O_<11> studied by high-resolution angle-resolved photoemission spectroscopy (2005)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: J. Electron Spec.Relat. Phenomena 16 ページ: 549-552
• [雑誌論文] High-resolution photoemission study of ZrZn_2 (2005)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: J.Electron.Spec.Relat. Phenomena 144-147 ページ: 889-891
  • NAID: 110002219395
• [雑誌論文] High-resolution photoemission angle-resolved photoemission study of layered transition-metal dichalcogenides Nb_<1-x>Ti_xXc_2(Xc=S,Se,Te) (2005)
  • 著者名/発表者名: T.Sato et al.
  • 雑誌名: J.Electron Spec.Relat.Phenomena 144-147 ページ: 633-637
• [雑誌論文] Direct observation of non-monotonic d_x2_<-y>2-wave superconducting gap in the electron-doped high-T_c superconductor Pr_<0.89>LaCe_<0.11>CuO_4 (2005)
  • 著者名/発表者名: H.Matsui et al.
  • 雑誌名: Physical Review Letters 95
• [雑誌論文] Momentum anisotropy of the scattering rate in cuprate superconductors (2005)
  • 著者名/発表者名: A.Kaminski et al.
  • 雑誌名: Physical Review B 71
• [雑誌論文] Direct observation of superconducting gap in YB_6 by ultrahigh-resolution photoemission spectroscopy (2005)
  • 著者名/発表者名: S.Souma et al.
  • 雑誌名: J.Electron Spec.Relat.Phenomena 144-147 ページ: 503-506
• [雑誌論文] Electronic band structure of AlB_2 studied by angle-resolved photoemission spectroscopy (2005)
  • 著者名/発表者名: S.Souma et al.
  • 雑誌名: J.Electron Spec.Relat.Phenomena 144-147 ページ: 545-547
• [雑誌論文] Ultrahigh-resolution photoemission study of h-ZrRuP (2005)
  • 著者名/発表者名: H.Matsui et al.
  • 雑誌名: J.Phys.Soc.Jpn. 74 ページ: 1401-1403
• [学会発表] 高分解能光電子分光装置の建設と銅酸化物高温超伝導体の電子構造の研究 (2008)
  • 著者名/発表者名: 佐藤宇史
  • 学会等名: 日本物理学会(第63回年次大会)
  • 発表場所: 近畿大学
  • 年月日: 2008-03-25
• [学会発表] High-resolution angle-resolved photoemission study of M_xCoO_2 (M: Na, K, Rb) (2007)
  • 著者名/発表者名: T. Arakane
  • 学会等名: 8th International Conference of Spectroscopyies of Novel Superconductors (invited)
  • 発表場所: 仙台
  • 年月日: 2007-08-24
• [学会発表] Many-body interactions in hole-doped high-Tc cuprates studied by high-resolution ARPES (2007)
  • 著者名/発表者名: T. Sato
  • 学会等名: 8th International Conference of Spectroscopyies of Novel Superconductors (invited)
  • 発表場所: 仙台
  • 年月日: 2007-08-23
• [学会発表] Universal character of CoO_2 plane studied by high-resolution angle-resolved photoemission (2007)
  • 著者名/発表者名: T. Arakane
  • 学会等名: 2007 International conference on Strongly Correlated Electron Systems
  • 発表場所: ヒューストン(アメリカ)
  • 年月日: 2007-05-13
• [図書] Very High Resolution Photoemission Spectroscopy (2007)
  • 著者名/発表者名: T.Takahashi et al.
  • 総ページ数: 22
  • 出版者: Springer, New York