2003 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) 福山秀敏東北大学, 金属材料研究所, 教授 (10004441) 今田正俊東京大学, 物性研究所, 教授 (70143542)
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	強相関電子系におけるスピン・軌道・電荷の自由度が織り成す多彩な現象を、量子モンテカルロ法、大規模行列厳密対角化等の数値的手法と、場の理論等の解析的手法の双方から調べた。具体的な成果は以下のとおりである。 (1)スピン液体に関して、(i)3角格子上のハバード模型において磁気秩序が存在しない新奇なスピン液体状態を理論的に見出した。(ii)3角格子上のハバード模型やt-J模型に関して、その超伝導状態の対称性に関する研究を行い、時間反転対称性の破れたペアー形成やスピン3重項状態の可能性を見出し、コバルト酸化物超伝導体の物性を議論した。 (2)軌道とスピンに関連した現象として、(i)ルテニウム酸化物、バナジウム酸化物を対象に、ヤーンテラー効果の大きさを定量的に評価し、軌道自由度の量子揺らぎの大きさを検討した。その結果、t2g電子でも軌道はほとんど古典的に振舞うことが見出された。(ii)異常量子ホール効果の第一原理計算を実行し、運動量空間におけるモノポールを見出すとともに、実験をほぼ完全に再現することに成功した。(iii)ESRの量子ダイナミックスを取り扱う理論を発展させた。(iv)チタン酸化物の軌道状態を理論的に調べ、最近の実験とよく符合する結果を得た。 (3)高温超伝導体と関連物質に関して、t-Jモデルにおける、電子格子相互作用を1/N展開で電子相関の効果を含めて調べ、光電子分光スペクトルの実験を検討した。

Research Products

(37 results)

All Other

All Publications (37 results)

[Publications] Mishchenko AS, NagaosaN, et al.: "Optical conductivity of the Frohlich polaron"Phys.Rev.Lett.. 91・23. art.no.236401 (2003)
[Publications] M.Mochizuki: "Orbital-Spin Structure and Lattice Coupling in RTiO_3 where R=La, Pr, Nd, and Sm"Phys.Rev.Lett.. 91. 167203 (2003)
[Publications] Motome Y, Furukawa N, Nagaosa N: "Competing orders and disorder-induced insulator to metal transition in manganites"Phys.Rev.Lett.. 91・16. art.no.167204 (2003)
[Publications] S.Onoda: "Mott Transitions in the Two-Dimensional Half-Filled Hubbard Model : Correlator Projection Method with Projective Dynamical Mean-Field Approximation"Physical Review B. 67. 161102(1)-161102(4) (2003)
[Publications] H.Tsuchiura, M.Ogata, Y.Tanaka, S.Kashiwaya: "Electronic states around a vortex core in high-T_c superconductors based on the t-J model"Physical Review B. 68. 012509 (2003)
[Publications] Matsuura M, Endoh Y, Hiraka H, et al.: "Classical and quantum spin dynamics in the fcc antiferromagnet NiS2 with frustration"Physical Review B. 68・9. art.no.094409 (2003)
[Publications] H.Onishi, S.Miyashita: "Effects of quantum lattice vibration on the spin-Peierls transition"Physica B. 329. 84-875 (2003)
[Publications] K.Saito, S.Miyashita: "Enhancement of the thermal conductivity in the spin-Peierls system"Physica B. 329. 876-877 (2003)
[Publications] S.Miyashita, N.Kojima: "Generalized Wajnflasz model for charge transfer spin-crossover phenomena"Progress of Theoretical Physics. 109・5. 729-739 (2003)
[Publications] S.Miyashita, K.Saito, H.Kobayashi: "Parity effect in the resonant tunneling"Progress of Theoretical Physics. 109・5. 741-749 (2003)
[Publications] S.Miyashita, K.Saito: "Real time scale simulation for quantum processes in dissipative environments"Physica B. 329. 1142-1143 (2003)
[Publications] M.Nishino, K.Saito, S.Miyashita: "Noise effect on resonant tunneling in the nanoscale molecular magnet(Fe-8)"Physics B. 329. 1170-1171 (2003)
[Publications] Y.Yanase, M.Ogata: "Microscopic Identification of the D-vector in Triplet Superconductor Sr_2RuO_4"Journal of Physical Society of Japan. 72. 673-687 (2003)
[Publications] S.Miyashita, A.Ogasahara: "Efffects of Dzyaloshinsky-Moriya interaction on ESR of Shastry-Sutherland model"Journal of the Physical Society of Japan. 72・9. 2350-2356 (2003)
[Publications] T.Koretsune, M.Ogata: "Ferromagnetism on the Frustrating Lattices"Journal of Physical Society of Japan. 72. 2437-2440 (2003)
[Publications] Z.Hiroi, K.Matsuhira, M.Ogata: "Ferromagnetic Ising Spin Chains Emerging from the Spin-Ice under Magnetic Field"Journal of Physical Society of Japan. 72. 3045-3048 (2003)
[Publications] M.Saito, T.Sasaki, H.Fukuyama: "Orbital magnetism in two-dimensional mesoscopic ring systems"Journal of the Physical Society of Japan. 72・10. 2556-2567 (2003)
[Publications] S.Miyashita, H.De Raedt, K.Mishielsen: "Directionally independent energy gap formation due to the hyperfine interaction"Progress of theoretical physics. 110・5. 889-899 (2003)
[Publications] Murakami S, Nagaosa N, Zhang SC: "Dissipationless quantum spin current at room temperature"SCIENCE. 301・5638. 1348-1351 (2003)
[Publications] Fang Z, Nagaosa N, Takahashi KS, et al.: "The anomalous Hall effect and magnetic monopoles in momentum space"SCIENCE. 302・5642. 92-95 (2003)
[Publications] Lee PA, Nagaosa N: "Collective modes in the superconducting ground states in the gauge theory description of the cuprates"Physical Review B. 68・2. art.no.024516 (2003)
[Publications] T.Mizusaki: "Precise Estimation of Shell Model Energy by Second-Order Extrapolation Method"Physical Review C. 67. 041301 (2003)
[Publications] Nagaosa N, Lee TK, Ho CM, et al.: "Theory of slightly doped Mott insulator"PHYSICA C. 388. 15-18 (2003)
[Publications] Murakami S, Nagaosa N: "Superconductivity with nonzero Chern numbers"PHYSICA C. 388. 53-54 (2003)
[Publications] Onoda M, Nagaosa N: "Quantized anomalous Hall effect in two-dimensional ferromagnets : Quantum Hall effect in metals"Phys.Rev.Lett.. 90・20. art.no.206601 (2003)
[Publications] Onoda S, Nagaosa N: "Spin chirality fluctuations and anomalous Hall effect in itinerant ferromagnets"Phys.Rev.Lett.. 90・19. art.no.196602 (2003)
[Publications] Murakami S, Nagaosa N: "Colossal magnetoresistance in manganites as a multicritical phenomenon"Phys.Rev.Lett.. 90・19. art.no.197201 (2003)
[Publications] Motome Y, Seo H, Fang Z, et al.: "One-dimensional confinement and enhanced Jahn-Teller instability in LaVO3"Phys.Rev.Lett.. 90・14. art.no.146602 (2003)
[Publications] Lee TK, Ho CM, Nagaosa N, et al.: "Theory for slightly doped antiferromagnetic Mott insulators"J LOW TEMP PHYS. 131・3-4. 169-179 (2003)
[Publications] M.Imada: "Path-Integral Renormalization Group Method"AIP Conference Proceedings : The Monte Carlo Method in the Physical Sciences Celebrating the 50^<th> Anniversary of the Metropolis Algorithm. 690. 207-217 (2003)
[Publications] M.Imada: "Tools for Studying quantum Emergence near Phase Transitions"AIP Conference Proceedings : The International Conference in Highlights in Condensed Matter Physics. 695. 75-91 (2003)
[Publications] M.Nishino, K.Boukheddaden, S.Miyashita, et al.: "Arrhenius Monte Carlo study of two-step spin crossover : Equilibrium and relaxation paths"Physical review B. 68・22. 224402-1-224402-10 (2003)
[Publications] 妹尾仁嗣, 鹿野田一司, 福山秀敏: "分子性結晶における電荷秩序"日本物理学会誌. 58・11. 801-808 (2003)
[Publications] N.Todoroki, S.Miyashita: "Ordered phase and phase transitions in the stacked triangular antiferromagnetic CsCoCl_3 and CsCoBr_3"Journal of the Physical Society of Japan. 73・2. 412-416 (2004)
[Publications] Y.Yamada, N.Todoroki, S.Miyashita: "Theory of ferromagnetic phase transition in SrTiO_3 isotope replacement"Physical review B. 69. 024103-024111 (2004)
[Publications] T.Mizusaki: "Quantum-Number Projection in the Path-Integral Renormalization Group Method"Phys.Rev.B. (to appear).
[Publications] S.Watanabe: "Precise Determination of Phase Diagram for Two-Dimensional Hubbard Model with Filling- and Bandwidth-Control Mott Transitions : Grand-Canonical Path-Integral Renormalization Group Approach"J.Phys.Soc.Jpn.. (to appear).

2003 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] Mishchenko AS, NagaosaN, et al.: "Optical conductivity of the Frohlich polaron"Phys.Rev.Lett.. 91・23. art.no.236401 (2003)

[Publications] M.Mochizuki: "Orbital-Spin Structure and Lattice Coupling in RTiO_3 where R=La, Pr, Nd, and Sm"Phys.Rev.Lett.. 91. 167203 (2003)

[Publications] Motome Y, Furukawa N, Nagaosa N: "Competing orders and disorder-induced insulator to metal transition in manganites"Phys.Rev.Lett.. 91・16. art.no.167204 (2003)

[Publications] S.Onoda: "Mott Transitions in the Two-Dimensional Half-Filled Hubbard Model : Correlator Projection Method with Projective Dynamical Mean-Field Approximation"Physical Review B. 67. 161102(1)-161102(4) (2003)

[Publications] H.Tsuchiura, M.Ogata, Y.Tanaka, S.Kashiwaya: "Electronic states around a vortex core in high-T_c superconductors based on the t-J model"Physical Review B. 68. 012509 (2003)

[Publications] Matsuura M, Endoh Y, Hiraka H, et al.: "Classical and quantum spin dynamics in the fcc antiferromagnet NiS2 with frustration"Physical Review B. 68・9. art.no.094409 (2003)

[Publications] H.Onishi, S.Miyashita: "Effects of quantum lattice vibration on the spin-Peierls transition"Physica B. 329. 84-875 (2003)

[Publications] K.Saito, S.Miyashita: "Enhancement of the thermal conductivity in the spin-Peierls system"Physica B. 329. 876-877 (2003)

[Publications] S.Miyashita, N.Kojima: "Generalized Wajnflasz model for charge transfer spin-crossover phenomena"Progress of Theoretical Physics. 109・5. 729-739 (2003)

[Publications] S.Miyashita, K.Saito, H.Kobayashi: "Parity effect in the resonant tunneling"Progress of Theoretical Physics. 109・5. 741-749 (2003)

[Publications] S.Miyashita, K.Saito: "Real time scale simulation for quantum processes in dissipative environments"Physica B. 329. 1142-1143 (2003)

[Publications] M.Nishino, K.Saito, S.Miyashita: "Noise effect on resonant tunneling in the nanoscale molecular magnet(Fe-8)"Physics B. 329. 1170-1171 (2003)

[Publications] Y.Yanase, M.Ogata: "Microscopic Identification of the D-vector in Triplet Superconductor Sr_2RuO_4"Journal of Physical Society of Japan. 72. 673-687 (2003)

[Publications] S.Miyashita, A.Ogasahara: "Efffects of Dzyaloshinsky-Moriya interaction on ESR of Shastry-Sutherland model"Journal of the Physical Society of Japan. 72・9. 2350-2356 (2003)

[Publications] T.Koretsune, M.Ogata: "Ferromagnetism on the Frustrating Lattices"Journal of Physical Society of Japan. 72. 2437-2440 (2003)

[Publications] Z.Hiroi, K.Matsuhira, M.Ogata: "Ferromagnetic Ising Spin Chains Emerging from the Spin-Ice under Magnetic Field"Journal of Physical Society of Japan. 72. 3045-3048 (2003)

[Publications] M.Saito, T.Sasaki, H.Fukuyama: "Orbital magnetism in two-dimensional mesoscopic ring systems"Journal of the Physical Society of Japan. 72・10. 2556-2567 (2003)

[Publications] S.Miyashita, H.De Raedt, K.Mishielsen: "Directionally independent energy gap formation due to the hyperfine interaction"Progress of theoretical physics. 110・5. 889-899 (2003)

[Publications] Murakami S, Nagaosa N, Zhang SC: "Dissipationless quantum spin current at room temperature"SCIENCE. 301・5638. 1348-1351 (2003)

[Publications] Fang Z, Nagaosa N, Takahashi KS, et al.: "The anomalous Hall effect and magnetic monopoles in momentum space"SCIENCE. 302・5642. 92-95 (2003)

[Publications] Lee PA, Nagaosa N: "Collective modes in the superconducting ground states in the gauge theory description of the cuprates"Physical Review B. 68・2. art.no.024516 (2003)

[Publications] T.Mizusaki: "Precise Estimation of Shell Model Energy by Second-Order Extrapolation Method"Physical Review C. 67. 041301 (2003)

[Publications] Nagaosa N, Lee TK, Ho CM, et al.: "Theory of slightly doped Mott insulator"PHYSICA C. 388. 15-18 (2003)

[Publications] Murakami S, Nagaosa N: "Superconductivity with nonzero Chern numbers"PHYSICA C. 388. 53-54 (2003)

[Publications] Onoda M, Nagaosa N: "Quantized anomalous Hall effect in two-dimensional ferromagnets : Quantum Hall effect in metals"Phys.Rev.Lett.. 90・20. art.no.206601 (2003)

[Publications] Onoda S, Nagaosa N: "Spin chirality fluctuations and anomalous Hall effect in itinerant ferromagnets"Phys.Rev.Lett.. 90・19. art.no.196602 (2003)

[Publications] Murakami S, Nagaosa N: "Colossal magnetoresistance in manganites as a multicritical phenomenon"Phys.Rev.Lett.. 90・19. art.no.197201 (2003)

[Publications] Motome Y, Seo H, Fang Z, et al.: "One-dimensional confinement and enhanced Jahn-Teller instability in LaVO3"Phys.Rev.Lett.. 90・14. art.no.146602 (2003)

[Publications] Lee TK, Ho CM, Nagaosa N, et al.: "Theory for slightly doped antiferromagnetic Mott insulators"J LOW TEMP PHYS. 131・3-4. 169-179 (2003)

[Publications] M.Imada: "Path-Integral Renormalization Group Method"AIP Conference Proceedings : The Monte Carlo Method in the Physical Sciences Celebrating the 50^<th> Anniversary of the Metropolis Algorithm. 690. 207-217 (2003)

[Publications] M.Imada: "Tools for Studying quantum Emergence near Phase Transitions"AIP Conference Proceedings : The International Conference in Highlights in Condensed Matter Physics. 695. 75-91 (2003)

[Publications] M.Nishino, K.Boukheddaden, S.Miyashita, et al.: "Arrhenius Monte Carlo study of two-step spin crossover : Equilibrium and relaxation paths"Physical review B. 68・22. 224402-1-224402-10 (2003)

[Publications] 妹尾仁嗣, 鹿野田一司, 福山秀敏: "分子性結晶における電荷秩序"日本物理学会誌. 58・11. 801-808 (2003)

[Publications] N.Todoroki, S.Miyashita: "Ordered phase and phase transitions in the stacked triangular antiferromagnetic CsCoCl_3 and CsCoBr_3"Journal of the Physical Society of Japan. 73・2. 412-416 (2004)

[Publications] Y.Yamada, N.Todoroki, S.Miyashita: "Theory of ferromagnetic phase transition in SrTiO_3 isotope replacement"Physical review B. 69. 024103-024111 (2004)

[Publications] T.Mizusaki: "Quantum-Number Projection in the Path-Integral Renormalization Group Method"Phys.Rev.B. (to appear).

[Publications] S.Watanabe: "Precise Determination of Phase Diagram for Two-Dimensional Hubbard Model with Filling- and Bandwidth-Control Mott Transitions : Grand-Canonical Path-Integral Renormalization Group Approach"J.Phys.Soc.Jpn.. (to appear).

永長直人東京大学, 大学院・工学系研究科, 教授 (60164406)