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

• Project/Area Number: 17684017
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics II
• Research Institution: Tohoku University
• Principal Investigator: 佐藤 宇史 Tohoku University, 大学院・理学研究科, 助教 (10361065)
• Project Period (FY): 2005 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥29,640,000 (Direct Cost: ¥22,800,000、Indirect Cost: ¥6,840,000); Fiscal Year 2007: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2006: ¥8,320,000 (Direct Cost: ¥6,400,000、Indirect Cost: ¥1,920,000); Fiscal Year 2005: ¥16,640,000 (Direct Cost: ¥12,800,000、Indirect Cost: ¥3,840,000)
• Keywords: 光電子分光 / 超伝導 / 遷移金属酸化物

Research Abstract

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。

Research Products

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