単層カーボンナノチューブの超高分解能光電子分光

• Project/Area Number: 16654052
• Research Category: Grant-in-Aid for Exploratory Research
• Allocation Type: Single-year Grants
• Research Field: Condensed matter physics II
• Research Institution: Tohoku University
• Principal Investigator: 佐藤 宇史 東北大学, 大学院理学研究科, 助手 (10361065)
• Project Period (FY): 2004 – 2006
• Project Status: Completed (Fiscal Year 2006)
• Budget Amount: ¥3,300,000 (Direct Cost: ¥3,300,000); Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000); Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
• Keywords: カーボンナノチューブ / 光電子分光

Research Abstract

単層カーボンナノチューブのフェルミ準位近傍の微細電子状態を決定する目的で、高分解能高電子分光装置の改良・調整を行った。具体的には、一体型電子衝撃高温加熱機構の改良・調整を行い、高温に耐えられるTa型試料基板の製作を行った。さらに、超高真空中でアルカリ金属をインターカレーションするための蒸着装置の設計・製作を行った。半金属Sb(111)試料を用いてCaの蒸着実験を行い、蒸着前後で表面バンドのエネルギー位置と形状に顕著な違いが見られることを見出した。このことから、実際に試料表面にCaが蒸着され、試料表面にキャリアーがドープされていることを確認した。ナノチューブの基本構造となる一枚層のグラファイト(グラフェン)を育成する目的で、試料作成槽に新たに通電加熱機構を設計・製作し、半導体表面の清浄化を可能にした。この装置を用いて、シリコンカーバイド(SiC)を1200°C以上に加熱してCを表面に析出させることにより、超高真空中で良質なグラフェンを育成することに成功した。ナノチューブの異常な電子状態と構造との関係を明らかにするために、ナノチューブ構造のベースとなるグラファイト単結晶の超高分解能光電子分光を行い、スペクトル形状の定量解析を行った。その結果、結合エネルギー0.2eV以上における準粒子の寿命が、典型的なフェルミ流体から大きく逸脱していることを見出した。また、フェルミ準位近傍において準粒子バンドに折れ曲がり(kink)構造が見られ、エネルギー位置がバルクのデバイ温度と良く対応していることから、その起源が強い電子格子相互作用に由来すると結論した。以上の事から、ナノチューブを始めとするすべてのグラファイト関連物質において、強い電子格子相互作用が異常物性に大きく影響していると結論した。

Research Products

• [Journal Article] Anomalous Quasiparticle Lifetime and Strong Electron-Phonon Coupling in Graphite (2007)
  • Author(s): K.Sugawara et al.
  • Journal Title: Physical Review Letters 98 Pages: 36801-36801
• [Journal Article] Anomalous electronic states in graphite studied by angle-resolved photoemission spectroscopy (2006)
  • Author(s): K.Sugawara et al.
  • Journal Title: Sci. Technol. Adv. Matter 7
• [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 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] 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
  • Journal Title: Phys.Rev.Lett. 94
• [Journal Article] Momentum anisotropy of the scattering rate in cuprate superconductors (2005)
  • Author(s): A.Kaminski
  • Journal Title: Phys.Rev.B 71
• [Journal Article] ARPES on Na_<0.6>CoO_2 : Fermi surface and unusual band dispersion (2004)
  • Author(s): H.-B.Yang
  • Journal Title: Phys.Rev.Lett. 92
• [Journal Article] X-ray angle-resolved photoemission spectroscopy of CaB_6 (2004)
  • Author(s): S.Souma
  • Journal Title: Phys.Rev.B 70
• [Journal Article] Identifying the background signal in angle-resolved photoemission spectra of high-temperature cuprate superconductors (2004)
  • Author(s): A.Kaminski
  • Journal Title: Phys.Rev.B 69
• [Journal Article] High-resolution angle-resolved photoemission study of incommensurate charge-density-wave compound CeTe_3 (2004)
  • Author(s): H.Komoda
  • Journal Title: Phys.Rev.B 70
• [Journal Article] Fermi surface topology of Ca_<1.5>Sr_<0.5>RuO_4 determined by ARPES (2004)
  • Author(s): S.-C.Wang
  • Journal Title: Phys.Rev.Lett. 93
• [Journal Article] Three-dimensional Fermi-surface nesting in 1T-VSe_2 studied by angle-resolved photoemission spectroscopy (2004)
  • Author(s): T.Sato
  • Journal Title: J.Phys.Soc.Jpn. 73 Pages: 3331-3334
  • NAID: 110001979302
• [Journal Article] Spectral evidence for Bogoliubov quasiparticle in triple-layered high-T_c superconductor Bi_2Sr_2Ca_2Cu_3O_<10> (2004)
  • Author(s): T.Takahashi
  • Journal Title: Physica C 408-410 Pages: 814-815
• [Journal Article] Fermi surface, superconducting gap, and many-body effects in Bi_2Sr_2Ca_<n-1>Cu_nO_<2n+4> (n=1-3) (2004)
  • Author(s): T.Sato
  • Journal Title: Physica C 408-410 Pages: 812-813
• [Journal Article] Direct observation of superconducting gaps in MgB_2 by angle-resolved photoemission spectroscopy (2004)
  • Author(s): S.Souma
  • Journal Title: Physica C 408-410 Pages: 102-103
• [Journal Article] Magnetic interaction in hole-doped high-T_c superconductors observed by angle-resolved photoemission spectroscopy (2004)
  • Author(s): T.Sato
  • Journal Title: Physica C 412-414 Pages: 103-108
• [Journal Article] Band structure and Fermi surface of CeB_6 studied by angle-resolved photoemission spectroscopy (2004)
  • Author(s): S.Soma
  • Journal Title: Physica B 351 Pages: 283-285
• [Journal Article] High-resolution angle-resolved photoemission study of LaRh_3B_2 (2004)
  • Author(s): Y.Iida
  • Journal Title: Physica B 31 Pages: 271-273
• [Journal Article] Electronic structure of layered transition-metal dichalcogenides Nb_<1-x>Ti_xXc_2(Xc=S,Se,Te) studied by angle-resolved photoemission spectroscopy (2004)
  • Author(s): T.Sato
  • Journal Title: J.Phys : Condens.Matter 16 Pages: 8599-8608
• [Journal Article] High-resolution angle-resolved photoemission study of impurity-substituted Bi_2Sr_2CaCu_2O_<8+δ> (2004)
  • Author(s): K.Terashima
  • Journal Title: Physica B 31 Pages: 280-282
• [Journal Article] High-resolution ARPES study of quasiparticles in high-T_c superconductors
  • Author(s): T.Takahashi
  • Journal Title: New Journal of Physics (In press)
• [Journal Article] Electronic structure of η-Mo_4O_<11> studied by high-resolution angle-resolved photoemission spectroscopy
  • Author(s): T.Sato
  • Journal Title: J.Electron Spec.Relat.Phenomena (In press)
• [Journal Article] High-resolution photoemission study of ZrZn_2
  • Author(s): T.Sato
  • Journal Title: J.Electron Spec.Relat.Phenomena (In press)
  • 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)
  • Author(s): T.Sato
  • Journal Title: J.Electron Spec.Relat.Phenomena (In press)
• [Journal Article] Direct observation of superconducting gap in YB_6 by ultrahigh-resolution photoemission spectroscopy
  • Author(s): S.Soma
  • Journal Title: J.Electron Spec.Relat.Phenomena (In press)
• [Journal Article] Electronic band structure of AlB_2 studied by angle-resolved photoemission spectroscopy
  • Author(s): S.Soma
  • Journal Title: J.Electron Spec.Relat.Phenomena (In press)