2001 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 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・理学系研究科, 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 / 起動 / 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新奇な量子現象を理論的に調べるために場の理論や計算物理の手法を発展させるとともにそれを高温超伝導体を始めとする遷移金属酸化物、有機導体、ナノ磁性体などに適用してその相図と量子ダイナミックスを明らかにした。具体的には 1.Sr2RuO4におけるスピン3重項超伝導の微視的な機構としてスピン揺らぎの理論を提唱した。 2.高温超伝導体中の磁性不純物のまわりの電子状態を変分波動関数で調べ、STMの実験と比較検討した。 3.フラストレートしている面心立方格子上の反強磁性体においてスピンカイラリィーが発生することを見出し、その輸送現象と軌道磁性を調べた。 4.ナノ磁性体における量子トンネル現象に関してランダムノイズの影響やクラマースの定理との関係を調べた。 5.ボロン化合物における高温強磁性の可能性を微視的な模型で検討し、複数のk-点の存在が不可欠であることを明らかにした。

Research Products

(21 results)

All Other

All Publications (21 results)

[Publications] Y.Taguchi et al.: "Spin chirality, Berry phase, and anomalous Hall effect in a frustrated ferromagnet"Science. 291. 2573 (2001)
[Publications] A.S.Mishchenko et al.: "Quasidegenerate self-trapping in one-dimensional charge transfer exciton"Phys. Rev. Lett.. 86・20. 4624-4627 (2001)
[Publications] C.-M.Ho et al.: "Nature of Spin Excitations in Two-Dimensional Mott Insulators : Undoped Cuprates and Other Materials"Phys. Rev. Lett.. 86. 1626-1629 (2001)
[Publications] R.Shindou et al.: "Orbital ferromagnetism and anomalous Hall effect in antiferromagnets on the distorted fcc lattice"Phys. Rev. Lett.. 87・11. 6801-6804 (2001)
[Publications] Chisa Hotta et al.: "Classification of the Ground States of Two-Dimensional Quarter-Filled Organic Conductors with Strong Dimerization"J. Phys. Soc. Jpn.. 70・2. 321-324 (2001)
[Publications] S.Watarai et al.: "Entropy Effect on the Magnetization Process of Hexagonal XY-like Heisenberg Antiferromagnets"J. Phys. Soc. Jpn.. 70. 532-537 (2001)
[Publications] Kimitaka Itoh et al.: "Transition of Radial Electric Field in Helical Systems"J. Phys. Soc. Jpn.. 70・6. 1575-1584 (2001)
[Publications] Hiroki Nakano et al.: "Magnetization Process of Nanoscale Iron Cluster"J. Phys. Soc. Jpn.. 70. 2151-2157 (2001)
[Publications] Tomokazu Matsuo et al.: "Application of Berezinskii's Diagram Method to Bond Disordered System with the Dimerization and the Staggered Field"J. Phys. Soc. Jpn.. 70・9. 2633-2644 (2001)
[Publications] S.Miyashita et al.: "A Microscopic Mechanism For Rejuvenation And Memory effects In Spin Glasses"Euro. Phys. B. 22. 203-211 (2001)
[Publications] K.Kuroki et al.: "Crib-shaped triplet-pairing gap function for an orthogonal pair of quasi-one-dimensional Fermi surfaces in Sr$ 2$RuO$ 4$"Phys. Rev. B. 63. 060506(R) (2001)
[Publications] Hiroaki Onishi et al.: "Spin-Peierls transition of the first order in S=1 antiferromagnetic Heisenberg chains"Phys. Rev. B. 64. 14405(1-7) (2001)
[Publications] H.Seo et al.: "Metallic State Driven by Frustrated Electronic Correlation in Cu-O Double Chain of PrBa$ 2$Cu$ 4$O$ 8$"Phys. Rev. B. 64. 2001-113103 (2001)
[Publications] S.Miyashita et al.: "Quantum Tunneling in Halh-Interger Spin Systems"Prog. Thore. Phys.. 106・3. 533-549 (2001)
[Publications] N.Nagaosa: "Competing orders and multicritical phenomena in strongly electronic systems"Physica C. 357. 53-60 (2001)
[Publications] M.Onoda et al.: "Topological nature of anomalous Hall effect in ferromagnets"J. Phys. Soc. Jpn.. 71・1. 19-22 (2002)
[Publications] S.Murakami et al.: "Theory of ferromagnetism in Ca$ {1-x}$La$ x$B$ 6$"Phys. Rev. Lett.. (Accepted). (2002)
[Publications] A.Himeda et al.: "Stripe States with Spatially Oscillaing d-wave superconductivity in the two dimensional $t$-$t'$-$J$ model"Phys. Rev. Lett.. (to appear). (2002)
[Publications] C.Hotta et al.: "Possible ferromagnetism in divalent borides"Phys. Rev. B. (to appear). (2002)
[Publications] H.Seo et al.: "Aspects of the Verwey transition in magnetite"Phys. Rev. B. (to appear). (2002)
[Publications] M.Saito et al.: "Impurity Induced Midgap State and Magnetism in Spin-Peierls Systems"J. Phys. Soc. Jpn.. (to appear). (2002)

2001 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] Y.Taguchi et al.: "Spin chirality, Berry phase, and anomalous Hall effect in a frustrated ferromagnet"Science. 291. 2573 (2001)

[Publications] A.S.Mishchenko et al.: "Quasidegenerate self-trapping in one-dimensional charge transfer exciton"Phys. Rev. Lett.. 86・20. 4624-4627 (2001)

[Publications] C.-M.Ho et al.: "Nature of Spin Excitations in Two-Dimensional Mott Insulators : Undoped Cuprates and Other Materials"Phys. Rev. Lett.. 86. 1626-1629 (2001)

[Publications] R.Shindou et al.: "Orbital ferromagnetism and anomalous Hall effect in antiferromagnets on the distorted fcc lattice"Phys. Rev. Lett.. 87・11. 6801-6804 (2001)

[Publications] Chisa Hotta et al.: "Classification of the Ground States of Two-Dimensional Quarter-Filled Organic Conductors with Strong Dimerization"J. Phys. Soc. Jpn.. 70・2. 321-324 (2001)

[Publications] S.Watarai et al.: "Entropy Effect on the Magnetization Process of Hexagonal XY-like Heisenberg Antiferromagnets"J. Phys. Soc. Jpn.. 70. 532-537 (2001)

[Publications] Kimitaka Itoh et al.: "Transition of Radial Electric Field in Helical Systems"J. Phys. Soc. Jpn.. 70・6. 1575-1584 (2001)

[Publications] Hiroki Nakano et al.: "Magnetization Process of Nanoscale Iron Cluster"J. Phys. Soc. Jpn.. 70. 2151-2157 (2001)

[Publications] Tomokazu Matsuo et al.: "Application of Berezinskii's Diagram Method to Bond Disordered System with the Dimerization and the Staggered Field"J. Phys. Soc. Jpn.. 70・9. 2633-2644 (2001)

[Publications] S.Miyashita et al.: "A Microscopic Mechanism For Rejuvenation And Memory effects In Spin Glasses"Euro. Phys. B. 22. 203-211 (2001)

[Publications] K.Kuroki et al.: "Crib-shaped triplet-pairing gap function for an orthogonal pair of quasi-one-dimensional Fermi surfaces in Sr$ 2$RuO$ 4$"Phys. Rev. B. 63. 060506(R) (2001)

[Publications] Hiroaki Onishi et al.: "Spin-Peierls transition of the first order in S=1 antiferromagnetic Heisenberg chains"Phys. Rev. B. 64. 14405(1-7) (2001)

[Publications] H.Seo et al.: "Metallic State Driven by Frustrated Electronic Correlation in Cu-O Double Chain of PrBa$ 2$Cu$ 4$O$ 8$"Phys. Rev. B. 64. 2001-113103 (2001)

[Publications] S.Miyashita et al.: "Quantum Tunneling in Halh-Interger Spin Systems"Prog. Thore. Phys.. 106・3. 533-549 (2001)

[Publications] N.Nagaosa: "Competing orders and multicritical phenomena in strongly electronic systems"Physica C. 357. 53-60 (2001)

[Publications] M.Onoda et al.: "Topological nature of anomalous Hall effect in ferromagnets"J. Phys. Soc. Jpn.. 71・1. 19-22 (2002)

[Publications] S.Murakami et al.: "Theory of ferromagnetism in Ca$ {1-x}$La$ x$B$ 6$"Phys. Rev. Lett.. (Accepted). (2002)

[Publications] A.Himeda et al.: "Stripe States with Spatially Oscillaing d-wave superconductivity in the two dimensional $t$-$t'$-$J$ model"Phys. Rev. Lett.. (to appear). (2002)

[Publications] C.Hotta et al.: "Possible ferromagnetism in divalent borides"Phys. Rev. B. (to appear). (2002)

[Publications] H.Seo et al.: "Aspects of the Verwey transition in magnetite"Phys. Rev. B. (to appear). (2002)

[Publications] M.Saito et al.: "Impurity Induced Midgap State and Magnetism in Spin-Peierls Systems"J. Phys. Soc. Jpn.. (to appear). (2002)

永長直人東京大学, 大学院・工学系研究科, 教授 (60164406)