2000 Fiscal Year Annual Research Report

スピン・電荷・軌道系の基礎理論

Research Project

Project/Area Number	12046218
Research Category	Grant-in-Aid for Scientific Research on Priority Areas (A)
Research Institution	The University of Tokyo
Principal Investigator	永長直人東京大学, 大学院・工学系研究科, 教授 (60164406)
Co-Investigator(Kenkyū-buntansha)	宮下精二東京大学, 大学院・工学系研究科, 教授 (10143372) 小形正男東京大学, 大学院・総合文化研究科, 助教授 (60185501) 福山秀敏東京大学, 物性研究所, 所長 (10004441)
Keywords	スピン / 電荷 / 軌道 / 遷移金属酸化物 / 高温超伝導 / 磁性体 / 量子臨界現象 / トポロジー
Research Abstract	スピン・電荷・軌道の自由度間の結合がもたらす多彩な現象を理論的に調べるために、場の理論や、グッツウィラー近似の改良など方法論を開発するとともに、それを高温超伝導体や有機導体、ナノ磁性体などの系に適用しその量子ダイナミックスを明らかにした。具体的には 1.高温超伝導体を記述する1次元および2次元t-Jモデルおよび関連するモデルについて、基底状態などの性質を調べた。その結果、ハーフフィリング近傍の、d波超伝導と反強磁性の共存、フェルミ面が自発的な変形、磁束近傍での振動するs波成分とゼロエネルギーピークの消滅などの新しい知見を得た。 2.有機導体における超伝導と反強磁性の競合における多重臨界現象の理論を構築し、新しい対称性(SO(5))の存在を提唱した。また局在スピンを持つ有機導体(π-d系)の多様な基底状態の系統性を究明した。 3.スピンのテクスチャーやスピン・軌道相互作用が電気伝導特に横伝導度に及ぼす影響を調べ、異常ホール効果の新しいメカニズムを提唱するとともにパイロクロア酸化物でそれが実現していることを実験の詳細な解析で基礎ずけた。 4.磁場下の限られた系での永久電流の空間分布をもとに、ランダウ反磁性の揺らぎとその起源を究明した。 5.不純物による量子核生成のミクロな理論の構築し、電荷密度波状態への応用を考察した。 6.スピンパイエルス転移の微視的機構やダイマー化したハイゼンベルグ反強磁性体での不純物誘起磁気構造を温度変化に着目して調べた。また、分子磁性体の量子ダイナミックスに関する散逸効果やESRのダイナミカルシフトが相互作用のタイプにどのように依存するかなど動的性質も研究した。

Research Products

(26 results)

All Other

All Publications (26 results)

[Publications] V.Ponomarenko et al: "Impurity pinning in transport through 1D Mott-Hubbard and spin gap insulators"Solid State Commun.. 114-1. 9-13 (2000)
[Publications] M.Nishimoto et al.: "Local magnetic structures induced by inhomogeneities of the lattice in S=1/2 bond-althernating chains and their response to a time-dependent magnetic field with noise."Physical Review.B.. 61-6. 9463-9471 (2000)
[Publications] K.Ohgushi et al.: "Spin anisotropy and quantum Hall effect in the Kagome lattice : Chiral spin state based on a ferromagnet"Physical Review.B.. 62-10. R6065-R6068 (2000)
[Publications] R.Maezono et al.: "Complex orbital states in manganese oxides"Physical Review.B.. 62-17. 11576-11580 (2000)
[Publications] A.Hams et al.: "Feedback effect on Landau-Zener-St[u-umlaut]ckelberg transitions in magnetic systems"Physical Review.B.. 62-21. 13880-13883 (2000)
[Publications] H.Fukuyama et al.: "Spin-Gap and Disorder"J.Phys.Soc.Jpn.. 69-Suppl.B. 122-126 (2000)
[Publications] H.Fukuyama et al.: "Interplay between Lattice Structure and Electronic Properties in Organic Conductors"J.Phys.Soc.Jpn.. 69-Suppl.B. 144-148 (2000)
[Publications] N.Nagaosa: "Aspects of strong coupling in gauge theory of high-Tc cuprates"J.Phys.Soc.Jpn.. 69-Suppl.B. 26-31 (2000)
[Publications] T.Arimori et al.: "Phase Diagram of Ising-Like Heisenberg Model on the Triangular Lattice with Degenerate Orbital Effect"J.Phys.Soc.Jpn.. 69-7. 2250-2260 (2000)
[Publications] S.Murakami et al.: "Multicritical Phenomena of Superconductivity and Antiferromagnetism in Organic Conductor κ-(BEDT-TTF)_<2X>"J.Phys.Soc.Jpn.. 69-8. 2395-2398 (2000)
[Publications] C.Hotta et al.: "Effects of Localized Spins in Quasi-Two Dimensional Organic Conductors"J.Phys.Soc.Jpn.. 69-8. 2577-2596 (2000)
[Publications] H.Onishi et al.: "Temperature Dependence of Spin and Bond Ordering in a Spin-Peierls System."J.Phys.Soc.Jpn.. 69-8. 2634-2641 (2000)
[Publications] M.Yumoto et al.: "Impurity Effects on Quantum Depinning of Commensurate Charge Density Waves"J.Phys.Soc.Jpn.. 69-9. 2953-2961 (2000)
[Publications] A.Ogasahara et al.: "ESR of Antiferromagnetic Cluster"J.Phys.Soc.Jpn.. 69-12. 4043-4048 (2000)
[Publications] Y.Tokura et al.: "Orbital Physics in Transition-Metal Oxides"Science. 288-5465. 462-467 (2000)
[Publications] H.Fukuyama et al.: "Interplay between Structure and Electronic Properties in Organic Conductors"Physica B. 280. 462-466 (2000)
[Publications] H.Yamase et al.: "Possible Quasi-One-Dimensional Fermi Surface in LSCO : Phenomenological Study"Physica B. 284-288. 1375-1376 (2000)
[Publications] H.Seo et al.: "Charge Ordering in Charge Transfer Organic Compounds"Physica B. 284-288. 1539-1540 (2000)
[Publications] H.Yamase et al.: "Quasi-One-Dimensional Band in the t-J Model"Physica C. 341-348. 321-322 (2000)
[Publications] H.Tsuchiura et al.: "Local density of states around a magnetic impurity in high-Tc superconductors based on the t-J model"Phys.Rev.Lett.. 84-14. 3165-3168 (2000)
[Publications] K.Kato et al.: "Quantum Phase Transition of the Randomly Diluted Heisenberg Antiferromagnet on a Square Lattice."Phys.Rev.Lett.. 84-18. 4204-4207 (2000)
[Publications] A.Himeda et al.: "Spontaneous Deformation of the Fermi Surface due to Strong Correlation in the Two-Dimensional t-J Model"Phys.Rev.Lett.. 85-20. 4345-4348 (2000)
[Publications] S.Watarai et al.: "Entropy effect on the magnetization process of Hexagonal XY-like Heisenberg antiferromagnets"J.Phys.Soc.Jpn.. 70. (2001)
[Publications] C.Yasuda et al.: "Classical Correlation-Length Exponent in Non-Universal Quantum Phase Transition of Diluted Heisenberg Antiferromagnet"J.Phys.Soc.Jpn.. 70. (2001)
[Publications] Y.Taguchi et al.: "Spin Chirality, Berry Phase, and Anomalous Hall Effect in a Frustrated Ferromagnet"to appear in Science. (2001)
[Publications] 永長直人: "第3の自由度-軌道-の物理学"クバプロ. 11 (2000)

2000 Fiscal Year Annual Research Report

スピン・電荷・軌道系の基礎理論

Principal Investigator

永長 直人 東京大学, 大学院・工学系研究科, 教授 (60164406)

Research Products

[Publications] V.Ponomarenko et al: "Impurity pinning in transport through 1D Mott-Hubbard and spin gap insulators"Solid State Commun.. 114-1. 9-13 (2000)

[Publications] M.Nishimoto et al.: "Local magnetic structures induced by inhomogeneities of the lattice in S=1/2 bond-althernating chains and their response to a time-dependent magnetic field with noise."Physical Review.B.. 61-6. 9463-9471 (2000)

[Publications] K.Ohgushi et al.: "Spin anisotropy and quantum Hall effect in the Kagome lattice : Chiral spin state based on a ferromagnet"Physical Review.B.. 62-10. R6065-R6068 (2000)

[Publications] R.Maezono et al.: "Complex orbital states in manganese oxides"Physical Review.B.. 62-17. 11576-11580 (2000)

[Publications] A.Hams et al.: "Feedback effect on Landau-Zener-St[u-umlaut]ckelberg transitions in magnetic systems"Physical Review.B.. 62-21. 13880-13883 (2000)

[Publications] H.Fukuyama et al.: "Spin-Gap and Disorder"J.Phys.Soc.Jpn.. 69-Suppl.B. 122-126 (2000)

[Publications] H.Fukuyama et al.: "Interplay between Lattice Structure and Electronic Properties in Organic Conductors"J.Phys.Soc.Jpn.. 69-Suppl.B. 144-148 (2000)

[Publications] N.Nagaosa: "Aspects of strong coupling in gauge theory of high-Tc cuprates"J.Phys.Soc.Jpn.. 69-Suppl.B. 26-31 (2000)

[Publications] T.Arimori et al.: "Phase Diagram of Ising-Like Heisenberg Model on the Triangular Lattice with Degenerate Orbital Effect"J.Phys.Soc.Jpn.. 69-7. 2250-2260 (2000)

[Publications] S.Murakami et al.: "Multicritical Phenomena of Superconductivity and Antiferromagnetism in Organic Conductor κ-(BEDT-TTF)_<2X>"J.Phys.Soc.Jpn.. 69-8. 2395-2398 (2000)

[Publications] C.Hotta et al.: "Effects of Localized Spins in Quasi-Two Dimensional Organic Conductors"J.Phys.Soc.Jpn.. 69-8. 2577-2596 (2000)

[Publications] H.Onishi et al.: "Temperature Dependence of Spin and Bond Ordering in a Spin-Peierls System."J.Phys.Soc.Jpn.. 69-8. 2634-2641 (2000)

[Publications] M.Yumoto et al.: "Impurity Effects on Quantum Depinning of Commensurate Charge Density Waves"J.Phys.Soc.Jpn.. 69-9. 2953-2961 (2000)

[Publications] A.Ogasahara et al.: "ESR of Antiferromagnetic Cluster"J.Phys.Soc.Jpn.. 69-12. 4043-4048 (2000)

[Publications] Y.Tokura et al.: "Orbital Physics in Transition-Metal Oxides"Science. 288-5465. 462-467 (2000)

[Publications] H.Fukuyama et al.: "Interplay between Structure and Electronic Properties in Organic Conductors"Physica B. 280. 462-466 (2000)

[Publications] H.Yamase et al.: "Possible Quasi-One-Dimensional Fermi Surface in LSCO : Phenomenological Study"Physica B. 284-288. 1375-1376 (2000)

[Publications] H.Seo et al.: "Charge Ordering in Charge Transfer Organic Compounds"Physica B. 284-288. 1539-1540 (2000)

[Publications] H.Yamase et al.: "Quasi-One-Dimensional Band in the t-J Model"Physica C. 341-348. 321-322 (2000)

[Publications] H.Tsuchiura et al.: "Local density of states around a magnetic impurity in high-Tc superconductors based on the t-J model"Phys.Rev.Lett.. 84-14. 3165-3168 (2000)

[Publications] K.Kato et al.: "Quantum Phase Transition of the Randomly Diluted Heisenberg Antiferromagnet on a Square Lattice."Phys.Rev.Lett.. 84-18. 4204-4207 (2000)

[Publications] A.Himeda et al.: "Spontaneous Deformation of the Fermi Surface due to Strong Correlation in the Two-Dimensional t-J Model"Phys.Rev.Lett.. 85-20. 4345-4348 (2000)

[Publications] S.Watarai et al.: "Entropy effect on the magnetization process of Hexagonal XY-like Heisenberg antiferromagnets"J.Phys.Soc.Jpn.. 70. (2001)

[Publications] C.Yasuda et al.: "Classical Correlation-Length Exponent in Non-Universal Quantum Phase Transition of Diluted Heisenberg Antiferromagnet"J.Phys.Soc.Jpn.. 70. (2001)

[Publications] Y.Taguchi et al.: "Spin Chirality, Berry Phase, and Anomalous Hall Effect in a Frustrated Ferromagnet"to appear in Science. (2001)

[Publications] 永長直人: "第3の自由度-軌道-の物理学"クバプロ. 11 (2000)

永長直人東京大学, 大学院・工学系研究科, 教授 (60164406)