2003 Fiscal Year Annual Research Report

遷移金属酸化物における電荷・軌道ダイナミックスのスペクトロスコピー

Research Project

Project/Area Number	12046220
Research Institution	The University of Tokyo
Principal Investigator	内田慎一東京大学, 大学院・理学系研究科, 教授 (10114399)
Co-Investigator(Kenkyū-buntansha)	松田祐司東京大学, 物性研究所, 助教授 (50199816) 藤森淳東京大学, 大学院・新領域創成科学研究科, 教授 (10209108)
Keywords	銅酸化物高温超伝導体 / 重い電子系 / 角度分解光電子分光(ARPES) / STM / STS / 熱伝導度 / 準粒子ダイナミックス / 熱伝導対称性
Research Abstract	銅酸化物を中心に遷移金属酸化物、スクッテルダイト、重い電子系を対象として、光電子分光(ARPES)、STS/STM、遠赤外分光、電子輸送現象等様々なスペクトロスコピー手法を用いて、実空間、運動量空間の電子構造、準粒子ダイナミックス、超伝導特性を探求した。 (1)銅酸化物研究においては、ARPESにより、第1ブリュアン帯対角線方向(d波ギャップのノード方向)の準粒子が稀薄ドーピング域でもギャップレスになっていることを発見した。このノード準粒子は超伝導相においても長い寿命をもち、量子力学干渉効果による電子密度の空間変調がSTM/STSで観測された。一方、ブリュアン帯端付近のアンチノード準粒子は、ノーマル状態でギャップをもつが、超伝導凝縮に直接関与していることを明らかにした。 (2)高温超伝導体La_<2-x>Sr_xCuO_4、YBa_2Cu_3O_<6+d>の比熱と電気伝導度を、角度分解光電子分光の測定結果により説明することを試みた。不足ドープ領域では、フェルミ面の一部(フェルミ・アーク)を除いて準粒子数そのものが減っていること、フェルミ・アーク上の準粒子数はドープしたホール濃度で与えられ、通常の機構で電気伝導に寄与することがわかった。また、Bi_2Sr_2CaCu_2O_<8+d>について化学ポテンシャルの温度変化を測定し、理論的予測と一致する結果を得た。 (3)異方的超伝導体の超伝導状態及びノーマル状態の研究を行った。スクッテルダイト超伝導体PrOs_4Sb_<12>の超伝導状態の研究では。熱伝導度を磁場を様々な方向にかけて測定することにより低磁場で結晶の対称性を破った2回対称の超伝導波動関数が現れていることを明らかにした。また2次元重い電子超伝導体CeCoIn_5のノーマル状態において電気抵抗、ホール係数、ネルンスト係数を測定しこれらは高温超伝導体と類似していることを明らかにした。

Research Products

(28 results)

All Other

All Publications (28 results)

[Publications] Y.Wang: "Dependence of Upper Critical Field and Pairing Strength on Doping in Cuprates"Science. 299. 86-89 (2003)
[Publications] K.McElroy: "Relating atomic-scale electronic phenomena to wave-like quasiparticle states in superconducting Bi_2Sr_2CaCu_2O_<8+δ>"Nature. 422. 592-596 (2003)
[Publications] N.Fujiwara: "Sperconductivity of the Sr_2Ca_<12>Cu_<24>O_<41> Spin-Ladder System"Phys.Rev.Lett.. 90. 137001 (2003)
[Publications] S.Uchida: "Critical Points in the Cuprate Phase Diagram"Solid State Commun.. 126. 57-61 (2003)
[Publications] B.Kuzmenko: "c-axis Optical Sum Rule and a Possible New Collective Mode in La_<2-x>Sr_xCuO_3"Phys.Rev.Lett.. 91. 037004 (2003)
[Publications] A.S.Moskvin: "Evidence for Two Types of Low-Energy Charge Transfer Excitation in Sr_2CuO_3"Phys.Rev.Lett.. 91. 037001 (2003)
[Publications] D.D.Sarma: "Metal-Insulator Cross-Over at the Surface of NiS_2"Phys.Rev.B. 67. 155112,1-155112,5 (2003)
[Publications] N.Harima: "Chemical Potential Shift in Bi_2Sr_2Ca_<1-x>it RxCu_2O_<8+y>(R= Pr, Er)"Phys.Rev.B. 67. 172501,1-172501-4 (2003)
[Publications] J.Zhou: "Univeral Nodal Fermi Velocity"Nature. 423. 397-398 (2003)
[Publications] T.Yoshida: "Nodal Metallic Behavior of Lightly-Doped La_<2-x>Sr_xCuO_4 with a Fermi Surface Forming an Arc"Phys.Rev.Lett.. 91. 027001,1-027001,4 (2003)
[Publications] J.Okamoto: "Photoemission Study of the Electronic Structure and the Metal-Semiconductor Transition in the Pyrochlore-Type Tl_<12>Ru_2O_7"Phys.Rev.B. 69. 035115,1-035115,6 (2004)
[Publications] S.Nawai: "Electronic Structure of the Kagome-Lattice Compound Rb_2Ni_3S_4"Phys.Rev.B. 69. 045103,1-045103,6 (2004)
[Publications] D.J.Huang: "Nature of Orbital Ordering in La_<0.5>Sr_<1.5>MnO_4 Studied by Soft X-Ray Linear Dichroism"Phys.Rev.Lett.. 92. 087202,1-087202,4 (2004)
[Publications] K.M.Shen: "Fully Gapped Single-Particle Excitations in the Lightly Doped Cuprates"Phys.Rev.B. (印刷中). (2003)
[Publications] K.Okazaki: "Electronic Structure of Quasi-One-Dimensional Superconductor Na_<0.33>V_2O_5"Phys.Rev.B. (印刷中). (2003)
[Publications] K.Okazaki: "Photoemission Study of the Metal-Insulator Transition in VO_2/TiO_2(001):Evidence for Strong Electron-Electron and Electron-Phonon Interaction"Phys.Rev.B. (印刷中). (2003)
[Publications] T.Yoshida: "ARPES study of lightly-doped La_<2-x>Sr_xCuO_4"Physica C. 388-389. 303-304 (2003)
[Publications] W.B.Wu: "Orbital Polarization of LaSrMnO_4 Studied by Soft X-Ray Linear Dichroism"J.Electron Spectrosc.Relat.Phenom.. (印刷中). (2004)
[Publications] J.Okamoto: "Magnetic Circular X-ray Dichroism Study of Paramagnetic and Anti-Ferromagnetic States in SrFeO_3 Using a 10-T Superconducting Magnet"AIP Proceedings. (印刷中). (2004)
[Publications] T.Yoshida: "Thermodynamic and Transport Properties of Underdoped Cuprates from ARPES Data"Physica B. (印刷中). (2004)
[Publications] K.Tanaka: "Effects of Next-Nearest-Neighbor Hopping t' on the Electronic Structure of Cuprates"Physica B. (印刷中). (2004)
[Publications] A.Ino: "ARPES Study of T^* Superconductor SmLa_<0.85>Sr_<0.15>CuO_4"Physica B. (印刷中). (2004)
[Publications] K.Izawa: "Multiple Superconducting Phases in New Heavy Fermion Superconductor PrOs_4Sb_<12>"Physical Review Letters. 90. 117001 (2003)
[Publications] K.Kakuyanagi: "Antiferromagnetic vortex core in Tl_2Ba_2CuO_<6+δ> studied by nuclear magnetic resonance"Physical Review Letters. 90. 197003 (2003)
[Publications] A.Shibata: "Anomalous Flux Flow Resistivity in Two Gap Superconductor MgB_2"Physical Review B. 68. 060501 (2003)
[Publications] S.Colson: "Vortex fluctuations in underdopedBi_2Sr_2CaCu_2O_<8+δ> crystals"Physical Review Letters. 90. 137002 (2003)
[Publications] Y.Nakajima: "Normal-state Hall Angle and Magnetoresistance in quasi-2D Heavy Fermion CeCoIn_5 near a Quantum Critical Point"Journal of Physical Society of Japan. 73. 5 (2004)
[Publications] R.Bel: "Giant Nernst Effect in CeCoIn5"Physical Review Letters. (in press). (2004)

2003 Fiscal Year Annual Research Report

遷移金属酸化物における電荷・軌道ダイナミックスのスペクトロスコピー

Principal Investigator

内田 慎一 東京大学, 大学院・理学系研究科, 教授 (10114399)

Research Products

[Publications] Y.Wang: "Dependence of Upper Critical Field and Pairing Strength on Doping in Cuprates"Science. 299. 86-89 (2003)

[Publications] K.McElroy: "Relating atomic-scale electronic phenomena to wave-like quasiparticle states in superconducting Bi_2Sr_2CaCu_2O_<8+δ>"Nature. 422. 592-596 (2003)

[Publications] N.Fujiwara: "Sperconductivity of the Sr_2Ca_<12>Cu_<24>O_<41> Spin-Ladder System"Phys.Rev.Lett.. 90. 137001 (2003)

[Publications] S.Uchida: "Critical Points in the Cuprate Phase Diagram"Solid State Commun.. 126. 57-61 (2003)

[Publications] B.Kuzmenko: "c-axis Optical Sum Rule and a Possible New Collective Mode in La_<2-x>Sr_xCuO_3"Phys.Rev.Lett.. 91. 037004 (2003)

[Publications] A.S.Moskvin: "Evidence for Two Types of Low-Energy Charge Transfer Excitation in Sr_2CuO_3"Phys.Rev.Lett.. 91. 037001 (2003)

[Publications] D.D.Sarma: "Metal-Insulator Cross-Over at the Surface of NiS_2"Phys.Rev.B. 67. 155112,1-155112,5 (2003)

[Publications] N.Harima: "Chemical Potential Shift in Bi_2Sr_2Ca_<1-x>it RxCu_2O_<8+y>(R= Pr, Er)"Phys.Rev.B. 67. 172501,1-172501-4 (2003)

[Publications] J.Zhou: "Univeral Nodal Fermi Velocity"Nature. 423. 397-398 (2003)

[Publications] T.Yoshida: "Nodal Metallic Behavior of Lightly-Doped La_<2-x>Sr_xCuO_4 with a Fermi Surface Forming an Arc"Phys.Rev.Lett.. 91. 027001,1-027001,4 (2003)

[Publications] J.Okamoto: "Photoemission Study of the Electronic Structure and the Metal-Semiconductor Transition in the Pyrochlore-Type Tl_<12>Ru_2O_7"Phys.Rev.B. 69. 035115,1-035115,6 (2004)

[Publications] S.Nawai: "Electronic Structure of the Kagome-Lattice Compound Rb_2Ni_3S_4"Phys.Rev.B. 69. 045103,1-045103,6 (2004)

[Publications] D.J.Huang: "Nature of Orbital Ordering in La_<0.5>Sr_<1.5>MnO_4 Studied by Soft X-Ray Linear Dichroism"Phys.Rev.Lett.. 92. 087202,1-087202,4 (2004)

[Publications] K.M.Shen: "Fully Gapped Single-Particle Excitations in the Lightly Doped Cuprates"Phys.Rev.B. (印刷中). (2003)

[Publications] K.Okazaki: "Electronic Structure of Quasi-One-Dimensional Superconductor Na_<0.33>V_2O_5"Phys.Rev.B. (印刷中). (2003)

[Publications] K.Okazaki: "Photoemission Study of the Metal-Insulator Transition in VO_2/TiO_2(001):Evidence for Strong Electron-Electron and Electron-Phonon Interaction"Phys.Rev.B. (印刷中). (2003)

[Publications] T.Yoshida: "ARPES study of lightly-doped La_<2-x>Sr_xCuO_4"Physica C. 388-389. 303-304 (2003)

[Publications] W.B.Wu: "Orbital Polarization of LaSrMnO_4 Studied by Soft X-Ray Linear Dichroism"J.Electron Spectrosc.Relat.Phenom.. (印刷中). (2004)

[Publications] J.Okamoto: "Magnetic Circular X-ray Dichroism Study of Paramagnetic and Anti-Ferromagnetic States in SrFeO_3 Using a 10-T Superconducting Magnet"AIP Proceedings. (印刷中). (2004)

[Publications] T.Yoshida: "Thermodynamic and Transport Properties of Underdoped Cuprates from ARPES Data"Physica B. (印刷中). (2004)

[Publications] K.Tanaka: "Effects of Next-Nearest-Neighbor Hopping t' on the Electronic Structure of Cuprates"Physica B. (印刷中). (2004)

[Publications] A.Ino: "ARPES Study of T^* Superconductor SmLa_<0.85>Sr_<0.15>CuO_4"Physica B. (印刷中). (2004)

[Publications] K.Izawa: "Multiple Superconducting Phases in New Heavy Fermion Superconductor PrOs_4Sb_<12>"Physical Review Letters. 90. 117001 (2003)

[Publications] K.Kakuyanagi: "Antiferromagnetic vortex core in Tl_2Ba_2CuO_<6+δ> studied by nuclear magnetic resonance"Physical Review Letters. 90. 197003 (2003)

[Publications] A.Shibata: "Anomalous Flux Flow Resistivity in Two Gap Superconductor MgB_2"Physical Review B. 68. 060501 (2003)

[Publications] S.Colson: "Vortex fluctuations in underdopedBi_2Sr_2CaCu_2O_<8+δ> crystals"Physical Review Letters. 90. 137002 (2003)

[Publications] Y.Nakajima: "Normal-state Hall Angle and Magnetoresistance in quasi-2D Heavy Fermion CeCoIn_5 near a Quantum Critical Point"Journal of Physical Society of Japan. 73. 5 (2004)

[Publications] R.Bel: "Giant Nernst Effect in CeCoIn5"Physical Review Letters. (in press). (2004)

内田慎一東京大学, 大学院・理学系研究科, 教授 (10114399)