1997 Fiscal Year Annual Research Report

異常金属相およびモット転移の理論

Research Project

Project/Area Number	07237102
Research Institution	University of Tokyo
Principal Investigator	今田正俊東京大学, 物性研究所, 教授 (70143542)
Co-Investigator(Kenkyū-buntansha)	寺倉清之産業技術融合領域研究所, 教授小谷章雄東京大学, 物性研究所, 教授 (90029504) 黒田義浩名古屋大学, 大学院・理学研究科, 教授 (60013504) 倉本義夫東北大学, 大学院・理学研究科, 教授 (70111250) 小形正男東京大学, 総合文化研究科, 助教授 (60185501)
Keywords	モット転移 / 軌道縮重効果 / 遷移金属酸化物 / 強相関電子系 / 酸化物高温超伝導体 / 量子臨界現象 / 非フェルミ液体 / インコヒーレント金属
Research Abstract	d電子系のモット絶縁体近傍の金属相、絶縁相、超伝導相についての理論的理解が大きく進んだ。本研究の中心課題である、金属絶縁体転移ないしモット転移について、動的臨界指数の大きな新たなユニヴァーサリティが見出され、強相関効果が電子励起の運動量に依存した特異的な繰り込みを生みだすことが重要であることがわかった。スピンないし軌道の揺らぎと運動量空間での縮退との相乗効果によって転移の異常さが理解されたことは大きな成果である。低次元性による特異的な運動量依存性がウムクラップ散乱やネスティング効果などを通じて現れることが明らかにされ、モット転移の量子臨界現象の理解は新たな段階へと入った。また一次元モット絶縁体の光電子スペクトルに現れる臨界現象、モット絶縁体の絶縁破壊についても理解は進んでいる。一方、マンガン酸化物などのd電子系の強相関効果とスピン、軌道縮重効果、ヤーンテラー効果などの電子格子相互作用をできる限り現実的な形で取り入れながら、金属相、絶縁相、スピン秩序、軌道秩序、格子変形などを計算し、実験結果を再現する研究が第一原理的な手法、強相関模型での研究などを通じて大きく進んだ。例えば、結晶の歪みによって引き起こされる、かなりの強さの磁気光効果が予言された。銅酸化物高温超伝導体の物性研究も成果が得られた。モット転移に伴う、二粒子過程の顕在化をモデル化したt-U-W模型を用いた研究で、モット絶縁体近傍でのd波超伝導体の顕著な性質が解明される一方、高温超伝導体の絶縁体状態からオーバー・ドープ領域までを統一的に記述できるモデルも提案された。ハバ-ド模型や梯子模型での超-伝導相関や輸送現象の研究も大きく進んだ。また銅酸化物高温超伝導体に於いて、反強磁性的絶縁体とd波一重項超伝導の境界を分ける、乱れによって支配される量子臨界点の存在の可能性が提唱された。またd波超伝導状態での磁束や境界の効果についての研究、トンネルスペクトルの研究によって、従来のs波超伝導と異なる性格が次々と明らかにされている。

Research Products

(44 results)

All Other

All Publications (44 results)

[Publications] T.Kato: "Vortices and Quantum Tunneling in Current-Biased O-π-O Josephson Junctions of α-Wave Superconductors" J.Phys.Soc.Jpn.66・5. 1445-1449 (1997)
[Publications] Y.Motome: "A Quantum Monte Carlo Method and Its Applications to Multi-Orbital Hubbard Models" J.Phys.Soc.Jpn.66・7. 1872-1875 (1997)
[Publications] M.Imada: "Suppressed Coherence due to Orbital Correlations in the Ferromagneticaply Ordeied Metallic Phase of Mn Compounds" J.Phys.Soc.Jpn.67・1. 45-48 (1998)
[Publications] K.Kuroki: "Enhancement of the dn^2-y^2 pairing correlation in the two-dimensional Hubberd maxel:a quantum Monte Carlo study" Phys.Rev.B. 56. R14287-14290 (1997)
[Publications] T.Kimura: "Pairing correlation in the three-Leg Hubbard ladder:renormalization group and quantum Monte Carlo studies" J.Phys.Soc.Jpn.to appear. 67. (1998)
[Publications] R.Arita: "DMRG study of the spin gap in a one dimensional Hubbard model:effect of the distant transfer and exchange caupling" Phys.Rev.B to appear. 57. (1998)
[Publications] S.Akazawa: "Dynamics of a Carrier in the Spin-Fermon Model with Hund Caupling" J.Phys.Soc.Jpn.66・9. 2758-2763 (1997)
[Publications] W.Koshibae: "Effects of Orbitals on the Magnetization Process in Monganites" J.Phys.Soc.Jpn.66・10. 2985-2988 (1997)
[Publications] H.Tsunetsugu: "The ground-state phase diagram of the one-dimensional Kondo lattice model" Rev.Mod.Phys.69. 809-863 (1997)
[Publications] N.Shibata: "Thermodynamics of the Anisotropic Heisenberg Chain Calculated by the Density Matrix Renormalization Group Method" J.Phys.Soc.Jpn.66. 2221-2223 (1997)
[Publications] M.Troyer: "Critical Exponents of the Quantum Phase Transition of a Planar Antiferromagnet" J.Phys.Soc.Jpn.66. 2957-2960 (1997)
[Publications] A.Himeda: "Theory of the Quasiparticle Spectra Around a Vortex in the Two-Dimensional t-J Model" J.Phys.Soc.Jpn.66. 3367-3370 (1997)
[Publications] M.Ogata: "A New Mean-Field Superconducting Phase in Two-Dimensional t-J Model near Half-Filling" J.Phys.Soc.Jpn.66. 3375-3378 (1997)
[Publications] Y.Tanuma: "Theory of Local Density of States of dx^2-y^2 Wave Superconducting State Noar the Surfaces of t-J Model" J.Phys.Soc.Jpn.to appear.
[Publications] T.Fujii: "Critical Properties of Spectral Functions for the ID Anisotropic t-J Models with an Energy Gap" J.Phys.Soc.Jpn.66. 806-809 (1997)
[Publications] S.Fujimoto: "Effects of Disorder on Two-Caupled Hubbard Chains at Half-Filling" Phys.Rev.B. 56. 9360-9369 (1997)
[Publications] A.Koga: "Mixed-Spin Ladders and Plaquette Spin Chains" J.Phys.Soc.Jpn.67. 199-205 (1998)
[Publications] 倉本義夫: "強磁場中量子ドットの電子状態と魔法数" 固体物理. 32. 42-48 (1997)
[Publications] Y.Kuramoto: "Dynamical Effective Medium Theory for Quantum Spins and Multipoles" J.Phys.Soc.Jpn.67. 583-593 (1997)
[Publications] S.Watanabe: "Competition between Crystalline Electric Field singlet and Itinerant States of f Electrons" Z.Phys.B. 104. 535-540 (1997)
[Publications] J.Okada: "Transport Coefficients for Many Electron System-Comparatire study of Moriformula and Kubo formula-" J.Phys.Soc.Jpn.66・9. 2790-2797 (1997)
[Publications] M.Azami: "Pairing Interaction and Superconducting Transition Temperature in the d-P Model" J.Phys.Soc.Jpn.66・9. 2811-2819 (1997)
[Publications] Y.Ono: "d-site Substitution Effects in the d-P Model" J.Phys.Soc.Jpn.67・1. 29-32 (1998)
[Publications] A.Kotani: "Theory of X-Ray Absorption and Resonant X-Ray Emission Spectra" J.Phys.IV France. 17・C2. 1-8 (1997)
[Publications] A.Kotani: "Interplay between Intra-Atomic Multiplet Coupling and Interatomic Hybridization in Core-Level Spectroscopy" Journal of Electron Spectroscopy and Related Phenomena. 86. 65-72 (1997)
[Publications] K.Okada: "Core-Level Photoemission Spectra of Low-Dimensional Copper-Oxide Systems" Journal of Electron Spectroscopy and Related Phenomena. 86. 119-126 (1997)
[Publications] Y.Tanaka: "Theory of Josephson Effects in Anisotropic Superconductors" Phys.Rev.B. 56・2. 892-912 (1997)
[Publications] H.Tsunetsugu: "Transport Propeities of Doped t-J Ladders" J.Phys.Soc.Jpn.66. 1876-1879 (1997)
[Publications] M.Arai: "Electronic Structures of Sr_<14-x>Ca_xCu_<24>O_<41>" Phys.Rev.B. 56. 4305-4308 (1997)
[Publications] I.V.Solovyev: "Magneto-Optical Effect in the Weak Ferromagnets LaMO_3(M=Cr,Mn and Fe)" Phys.Rev.B. 55・13. 8060-8063 (1997)
[Publications] 寺倉清之: "ペロフスカイト遷移金属酸化物の構造,電子状態,磁性" 固体物理. 32・4. 71-81 (1997)
[Publications] H.Sawada: "Jahn-Teller Distation and Mognetic Structures in LaMnO_3" Phys.Rev.B. 56・19. 12154-12160 (1997)
[Publications] N.Nagaasa: "Kondo Effect in High-Tc Cuprates" Phys.Rev.Lett.79. 3755-3758 (1997)
[Publications] S.Ishihara: "Optical Spectra in Charge Ordered Perovskite" J.Phys.Soc.Jpn.66・11. 3678-3682 (1997)
[Publications] K.Imura: "Quantum Transport in U=2/3Spin-Singlet Quantum Hall Edges Franctional Quantum Hall Effect" Phys.Rev.B to appear. 57・12. (1998)
[Publications] N.Hamada: "Efectronic Band Structure and Lattice Distortion in Perovskite Transition-Metal Oxides" Physica B. 237-238. 11 (1997)
[Publications] C.Kim: "Separation of Spinand Charge Excitations in one-Dimensional SrCuO_2" Phys.Rev.B. 56・24. 15589-15595 (1997)
[Publications] S.Ishihara: "Effective Hamiltonian in manganites:Study of the Orbital and spin structures" Phys.Rev.B. 55・13. 8280-8286 (1997)
[Publications] H.Maebashi: "Electrical Conductivity of Interacting Fermionsl.General Formulation" J.Phys.Soc.Jpn.66. 3577-3590 (1997)
[Publications] M.Saito: "Magnetic Excitations in Disorlered Spin-Peierls Systems" J.Phys.Soc.Jpn.66. 3259-3271 (1997)
[Publications] O.Narikiyo: "Nested Spin-Fluctuation Theory for Magnetotransport in the Normal State of High-Tc Cuprates-Violation of Kohlers's Rule" J.Phys.Soc.Jpn.66・5. 1561-1562 (1997)
[Publications] Y.Okuno: "Renormalized Perturbation Approach for Examination of Itinerant-Localized Duality Model for Strongly Correlatead Election Systems" J.Phys.Soc.Jpn.66・8. 2389-2398 (1997)
[Publications] S.Koikegami: "Strong Caupling Approach of the d-P Madelon the Basis of Fermi Liquid Theory" J.Phys.Soc.Jpn.to appear. 67・4. (1998)
[Publications] T.Ichinomiya: "NMR Relaxation Rate and Resistirity in Organic Superconductors" J.Phys.Soc.Jpn.66・10. 3202-3210 (1997)

1997 Fiscal Year Annual Research Report

異常金属相およびモット転移の理論

Principal Investigator

今田 正俊 東京大学, 物性研究所, 教授 (70143542)

Research Products

[Publications] T.Kato: "Vortices and Quantum Tunneling in Current-Biased O-π-O Josephson Junctions of α-Wave Superconductors" J.Phys.Soc.Jpn.66・5. 1445-1449 (1997)

[Publications] Y.Motome: "A Quantum Monte Carlo Method and Its Applications to Multi-Orbital Hubbard Models" J.Phys.Soc.Jpn.66・7. 1872-1875 (1997)

[Publications] M.Imada: "Suppressed Coherence due to Orbital Correlations in the Ferromagneticaply Ordeied Metallic Phase of Mn Compounds" J.Phys.Soc.Jpn.67・1. 45-48 (1998)

[Publications] K.Kuroki: "Enhancement of the dn^2-y^2 pairing correlation in the two-dimensional Hubberd maxel:a quantum Monte Carlo study" Phys.Rev.B. 56. R14287-14290 (1997)

[Publications] T.Kimura: "Pairing correlation in the three-Leg Hubbard ladder:renormalization group and quantum Monte Carlo studies" J.Phys.Soc.Jpn.to appear. 67. (1998)

[Publications] R.Arita: "DMRG study of the spin gap in a one dimensional Hubbard model:effect of the distant transfer and exchange caupling" Phys.Rev.B to appear. 57. (1998)

[Publications] S.Akazawa: "Dynamics of a Carrier in the Spin-Fermon Model with Hund Caupling" J.Phys.Soc.Jpn.66・9. 2758-2763 (1997)

[Publications] W.Koshibae: "Effects of Orbitals on the Magnetization Process in Monganites" J.Phys.Soc.Jpn.66・10. 2985-2988 (1997)

[Publications] H.Tsunetsugu: "The ground-state phase diagram of the one-dimensional Kondo lattice model" Rev.Mod.Phys.69. 809-863 (1997)

[Publications] N.Shibata: "Thermodynamics of the Anisotropic Heisenberg Chain Calculated by the Density Matrix Renormalization Group Method" J.Phys.Soc.Jpn.66. 2221-2223 (1997)

[Publications] M.Troyer: "Critical Exponents of the Quantum Phase Transition of a Planar Antiferromagnet" J.Phys.Soc.Jpn.66. 2957-2960 (1997)

[Publications] A.Himeda: "Theory of the Quasiparticle Spectra Around a Vortex in the Two-Dimensional t-J Model" J.Phys.Soc.Jpn.66. 3367-3370 (1997)

[Publications] M.Ogata: "A New Mean-Field Superconducting Phase in Two-Dimensional t-J Model near Half-Filling" J.Phys.Soc.Jpn.66. 3375-3378 (1997)

[Publications] Y.Tanuma: "Theory of Local Density of States of dx^2-y^2 Wave Superconducting State Noar the Surfaces of t-J Model" J.Phys.Soc.Jpn.to appear.

[Publications] T.Fujii: "Critical Properties of Spectral Functions for the ID Anisotropic t-J Models with an Energy Gap" J.Phys.Soc.Jpn.66. 806-809 (1997)

[Publications] S.Fujimoto: "Effects of Disorder on Two-Caupled Hubbard Chains at Half-Filling" Phys.Rev.B. 56. 9360-9369 (1997)

[Publications] A.Koga: "Mixed-Spin Ladders and Plaquette Spin Chains" J.Phys.Soc.Jpn.67. 199-205 (1998)

[Publications] 倉本 義夫: "強磁場中量子ドットの電子状態と魔法数" 固体物理. 32. 42-48 (1997)

[Publications] Y.Kuramoto: "Dynamical Effective Medium Theory for Quantum Spins and Multipoles" J.Phys.Soc.Jpn.67. 583-593 (1997)

[Publications] S.Watanabe: "Competition between Crystalline Electric Field singlet and Itinerant States of f Electrons" Z.Phys.B. 104. 535-540 (1997)

[Publications] J.Okada: "Transport Coefficients for Many Electron System-Comparatire study of Moriformula and Kubo formula-" J.Phys.Soc.Jpn.66・9. 2790-2797 (1997)

[Publications] M.Azami: "Pairing Interaction and Superconducting Transition Temperature in the d-P Model" J.Phys.Soc.Jpn.66・9. 2811-2819 (1997)

[Publications] Y.Ono: "d-site Substitution Effects in the d-P Model" J.Phys.Soc.Jpn.67・1. 29-32 (1998)

[Publications] A.Kotani: "Theory of X-Ray Absorption and Resonant X-Ray Emission Spectra" J.Phys.IV France. 17・C2. 1-8 (1997)

[Publications] A.Kotani: "Interplay between Intra-Atomic Multiplet Coupling and Interatomic Hybridization in Core-Level Spectroscopy" Journal of Electron Spectroscopy and Related Phenomena. 86. 65-72 (1997)

[Publications] K.Okada: "Core-Level Photoemission Spectra of Low-Dimensional Copper-Oxide Systems" Journal of Electron Spectroscopy and Related Phenomena. 86. 119-126 (1997)

[Publications] Y.Tanaka: "Theory of Josephson Effects in Anisotropic Superconductors" Phys.Rev.B. 56・2. 892-912 (1997)

[Publications] H.Tsunetsugu: "Transport Propeities of Doped t-J Ladders" J.Phys.Soc.Jpn.66. 1876-1879 (1997)

[Publications] M.Arai: "Electronic Structures of Sr_<14-x>Ca_xCu_<24>O_<41>" Phys.Rev.B. 56. 4305-4308 (1997)

[Publications] I.V.Solovyev: "Magneto-Optical Effect in the Weak Ferromagnets LaMO_3(M=Cr,Mn and Fe)" Phys.Rev.B. 55・13. 8060-8063 (1997)

[Publications] 寺倉 清之: "ペロフスカイト遷移金属酸化物の構造,電子状態,磁性" 固体物理. 32・4. 71-81 (1997)

[Publications] H.Sawada: "Jahn-Teller Distation and Mognetic Structures in LaMnO_3" Phys.Rev.B. 56・19. 12154-12160 (1997)

[Publications] N.Nagaasa: "Kondo Effect in High-Tc Cuprates" Phys.Rev.Lett.79. 3755-3758 (1997)

[Publications] S.Ishihara: "Optical Spectra in Charge Ordered Perovskite" J.Phys.Soc.Jpn.66・11. 3678-3682 (1997)

[Publications] K.Imura: "Quantum Transport in U=2/3Spin-Singlet Quantum Hall Edges Franctional Quantum Hall Effect" Phys.Rev.B to appear. 57・12. (1998)

[Publications] N.Hamada: "Efectronic Band Structure and Lattice Distortion in Perovskite Transition-Metal Oxides" Physica B. 237-238. 11 (1997)

[Publications] C.Kim: "Separation of Spinand Charge Excitations in one-Dimensional SrCuO_2" Phys.Rev.B. 56・24. 15589-15595 (1997)

[Publications] S.Ishihara: "Effective Hamiltonian in manganites:Study of the Orbital and spin structures" Phys.Rev.B. 55・13. 8280-8286 (1997)

[Publications] H.Maebashi: "Electrical Conductivity of Interacting Fermionsl.General Formulation" J.Phys.Soc.Jpn.66. 3577-3590 (1997)

[Publications] M.Saito: "Magnetic Excitations in Disorlered Spin-Peierls Systems" J.Phys.Soc.Jpn.66. 3259-3271 (1997)

[Publications] O.Narikiyo: "Nested Spin-Fluctuation Theory for Magnetotransport in the Normal State of High-Tc Cuprates-Violation of Kohlers's Rule" J.Phys.Soc.Jpn.66・5. 1561-1562 (1997)

[Publications] Y.Okuno: "Renormalized Perturbation Approach for Examination of Itinerant-Localized Duality Model for Strongly Correlatead Election Systems" J.Phys.Soc.Jpn.66・8. 2389-2398 (1997)

[Publications] S.Koikegami: "Strong Caupling Approach of the d-P Madelon the Basis of Fermi Liquid Theory" J.Phys.Soc.Jpn.to appear. 67・4. (1998)

[Publications] T.Ichinomiya: "NMR Relaxation Rate and Resistirity in Organic Superconductors" J.Phys.Soc.Jpn.66・10. 3202-3210 (1997)

今田正俊東京大学, 物性研究所, 教授 (70143542)

[Publications] 倉本義夫: "強磁場中量子ドットの電子状態と魔法数" 固体物理. 32. 42-48 (1997)

[Publications] 寺倉清之: "ペロフスカイト遷移金属酸化物の構造,電子状態,磁性" 固体物理. 32・4. 71-81 (1997)