1997 年度実績報告書

異常金属相およびモット転移の理論

研究課題

研究課題/領域番号	07237102
研究機関	東京大学
研究代表者	今田正俊東京大学, 物性研究所, 教授 (70143542)
研究分担者	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)
キーワード	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
研究概要	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。

研究成果
(44件)

すべてその他

すべて文献書誌 (44件)

[文献書誌] 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)
[文献書誌] Y.Motome: "A Quantum Monte Carlo Method and Its Applications to Multi-Orbital Hubbard Models" J.Phys.Soc.Jpn.66・7. 1872-1875 (1997)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] S.Akazawa: "Dynamics of a Carrier in the Spin-Fermon Model with Hund Caupling" J.Phys.Soc.Jpn.66・9. 2758-2763 (1997)
[文献書誌] W.Koshibae: "Effects of Orbitals on the Magnetization Process in Monganites" J.Phys.Soc.Jpn.66・10. 2985-2988 (1997)
[文献書誌] H.Tsunetsugu: "The ground-state phase diagram of the one-dimensional Kondo lattice model" Rev.Mod.Phys.69. 809-863 (1997)
[文献書誌] N.Shibata: "Thermodynamics of the Anisotropic Heisenberg Chain Calculated by the Density Matrix Renormalization Group Method" J.Phys.Soc.Jpn.66. 2221-2223 (1997)
[文献書誌] M.Troyer: "Critical Exponents of the Quantum Phase Transition of a Planar Antiferromagnet" J.Phys.Soc.Jpn.66. 2957-2960 (1997)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] 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.
[文献書誌] 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)
[文献書誌] S.Fujimoto: "Effects of Disorder on Two-Caupled Hubbard Chains at Half-Filling" Phys.Rev.B. 56. 9360-9369 (1997)
[文献書誌] A.Koga: "Mixed-Spin Ladders and Plaquette Spin Chains" J.Phys.Soc.Jpn.67. 199-205 (1998)
[文献書誌] 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)
[文献書誌] Y.Kuramoto: "Dynamical Effective Medium Theory for Quantum Spins and Multipoles" J.Phys.Soc.Jpn.67. 583-593 (1997)
[文献書誌] S.Watanabe: "Competition between Crystalline Electric Field singlet and Itinerant States of f Electrons" Z.Phys.B. 104. 535-540 (1997)
[文献書誌] J.Okada: "Transport Coefficients for Many Electron System-Comparatire study of Moriformula and Kubo formula-" J.Phys.Soc.Jpn.66・9. 2790-2797 (1997)
[文献書誌] M.Azami: "Pairing Interaction and Superconducting Transition Temperature in the d-P Model" J.Phys.Soc.Jpn.66・9. 2811-2819 (1997)
[文献書誌] Y.Ono: "d-site Substitution Effects in the d-P Model" J.Phys.Soc.Jpn.67・1. 29-32 (1998)
[文献書誌] A.Kotani: "Theory of X-Ray Absorption and Resonant X-Ray Emission Spectra" J.Phys.IV France. 17・C2. 1-8 (1997)
[文献書誌] 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)
[文献書誌] K.Okada: "Core-Level Photoemission Spectra of Low-Dimensional Copper-Oxide Systems" Journal of Electron Spectroscopy and Related Phenomena. 86. 119-126 (1997)
[文献書誌] Y.Tanaka: "Theory of Josephson Effects in Anisotropic Superconductors" Phys.Rev.B. 56・2. 892-912 (1997)
[文献書誌] H.Tsunetsugu: "Transport Propeities of Doped t-J Ladders" J.Phys.Soc.Jpn.66. 1876-1879 (1997)
[文献書誌] M.Arai: "Electronic Structures of Sr_<14-x>Ca_xCu_<24>O_<41>" Phys.Rev.B. 56. 4305-4308 (1997)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] H.Sawada: "Jahn-Teller Distation and Mognetic Structures in LaMnO_3" Phys.Rev.B. 56・19. 12154-12160 (1997)
[文献書誌] N.Nagaasa: "Kondo Effect in High-Tc Cuprates" Phys.Rev.Lett.79. 3755-3758 (1997)
[文献書誌] S.Ishihara: "Optical Spectra in Charge Ordered Perovskite" J.Phys.Soc.Jpn.66・11. 3678-3682 (1997)
[文献書誌] K.Imura: "Quantum Transport in U=2/3Spin-Singlet Quantum Hall Edges Franctional Quantum Hall Effect" Phys.Rev.B to appear. 57・12. (1998)
[文献書誌] N.Hamada: "Efectronic Band Structure and Lattice Distortion in Perovskite Transition-Metal Oxides" Physica B. 237-238. 11 (1997)
[文献書誌] C.Kim: "Separation of Spinand Charge Excitations in one-Dimensional SrCuO_2" Phys.Rev.B. 56・24. 15589-15595 (1997)
[文献書誌] S.Ishihara: "Effective Hamiltonian in manganites:Study of the Orbital and spin structures" Phys.Rev.B. 55・13. 8280-8286 (1997)
[文献書誌] H.Maebashi: "Electrical Conductivity of Interacting Fermionsl.General Formulation" J.Phys.Soc.Jpn.66. 3577-3590 (1997)
[文献書誌] M.Saito: "Magnetic Excitations in Disorlered Spin-Peierls Systems" J.Phys.Soc.Jpn.66. 3259-3271 (1997)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] 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)
[文献書誌] T.Ichinomiya: "NMR Relaxation Rate and Resistirity in Organic Superconductors" J.Phys.Soc.Jpn.66・10. 3202-3210 (1997)

1997 年度 実績報告書

異常金属相およびモット転移の理論

研究代表者

今田 正俊 東京大学, 物性研究所, 教授 (70143542)

研究成果

[文献書誌] 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)

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

[文献書誌] 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)

[文献書誌] 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)

[文献書誌] 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)

[文献書誌] 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)

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

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

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

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

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

[文献書誌] 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)

[文献書誌] 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)

[文献書誌] 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.

[文献書誌] 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)

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

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

[文献書誌] 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)

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

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

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

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

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

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

[文献書誌] 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)

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

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

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

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

[文献書誌] 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)

[文献書誌] 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)

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

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

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

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

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

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

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

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

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

[文献書誌] 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)

[文献書誌] 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)

[文献書誌] 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)

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

1997 年度実績報告書

今田正俊東京大学, 物性研究所, 教授 (70143542)

[文献書誌] 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)

[文献書誌] 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)