2002 Fiscal Year Annual Research Report

低次元分子性導体の電荷秩序と絶縁機構、光誘起非線型ダイナミクス

Research Project

Project/Area Number	12640361
Research Institution	Okazaki National Research Institutes
Principal Investigator	米満賢治岡崎国立共同研究機構, 分子科学研究所, 助教授 (60270823)
Co-Investigator(Kenkyū-buntansha)	岸根順一郎岡崎国立共同研究機構, 分子科学研究所, 助手 (80290906)
Keywords	交互積層型電荷移動錯体 / ハロゲン架橋白金錯体 / スピンクロスオーバー錯体 / 中性イオン性相転移 / 光誘起相転移 / 電荷密度波電荷分極相転移 / 時間依存量子発展方程式 / モンテカルロ計算
Research Abstract	電荷移動錯体TTF-CAは低温または高圧下で常誘電中性相から二量化を伴う強誘電イオン性相へ転移することが知られている。さらに光照射によっても両方向へ相転移し、その時間発展が実験で明らかになりつつある。1次元拡張パイエルス・ハバードモデルを平均場近似し、時間依存シュレディンガー方程式を解き、イオン性相からの電荷密度と格子変位のダイナミクスを追った。光励起を強くすると中性ドメインがより多く生成され、閾値強度以上で中性相へ転移した。電荷移動量の時間変化をフーリエ解析した。電子のバンド間遷移に由来する速い振動、格子振動に由来する遅い振動・中性イオン性相境界の集団運動に由来するさらに遅い振動に分類された。光励起を強くすると励起子効果が強くなることがわかった。光照射により初期のイオン性相とは反対方向に分極するイオン性ドメインが生まれる。これにより格子秩序が電荷移動量に比べてずっと速く減衰する。これは反射率変化よりも第二次高調波変化が速く起こる実験結果と矛盾しない。イオン性ドメイン間のソリトンが多いと、中性イオン性相境界と干渉することにより相転移に長い時間を要することがわかった。ヨウ素架橋複核白金錯体で配位子がPOPの物質群はCDW相と電荷分極(CP)相が複核間距離で整理され、電子間と電子格子間の相互作用の競合で理論的に説明される。高圧下不連続転移するものをヒステリシスループ内で光照射すると、CDW相からCP相へは光誘起相転移するが逆は起こりにくい。この機構も1次元拡張パイエルス・ハバードモデルで理論的に説明される。CDW相では複核間で電荷不均化するので、複核間電荷移動が低エネルギーで起こる。CP相では複核内で電荷不均化するので、複核内電荷移動がより低エネルギーで起こる。後者を低エネルギーで光照射しても複核間の電荷移動を伴わず、高エネルギーで複核間の電荷移動を強制してもそれが核となって自己増殖することができない。

Research Products

(17 results)

All Other

All Publications (17 results)

[Publications] K.Yonemitsu: "Quantum and Thermal Charge-Transfer Fluctuations for Neutral-Ionic Phase Transitions in the One-Dimensional Extended Hubbard Model with Alternating Potentials"Physical Review B. 65. 085105 (2002)
[Publications] K.Yonemitsu: "Lattice and Magnetic Instabilities near the Neutral-Ionic Phase Transition of the One-Dimensional Extended Hubbard Model with Alternating Potentials in the Thermodynamic Limit"Physical Review B. 65. 205105 (2002)
[Publications] K.Yonemitsu: "Collective Excitations and Confinement in the Excitation Spectra of the Spinless Fermion Model on a Ladder"Physical Review B. 66. 035121 (2002)
[Publications] J.Kishine, K.Yonemitsu: "Dimensional Crossovers and Phase Transitions in Strongly Correlated Low-Dimensional Electron Systems : Renormalization-Group Study"International Journal of Modern Physics B. 16. 711-771 (2002)
[Publications] K.Yonemitsu: "Variation of Excitation Spectra in Mixed-Stack Charge-Transfer Complexes"Phase Transitions. 75. 759-767 (2002)
[Publications] N.Miyashita, M.Kuwabara, K.Ybnemitsu: "Domain-Wall Dynamics after Photoexcitations near Neutral-Ionic Phase Transitions"Phase Transitions. 75. 887-893 (2002)
[Publications] J.Kishine, P.A.Lee, X-G Wen: "Signature of the Staggered Flux State around a Superconducting Vortex in Underdoped Cuprates"Physical Review B. 65. 064526 (2002)
[Publications] K.Yonemitsu: "Intra-and Inter-Chain Excitations near a Quantum Phase Transition in Quasi-One-Dimensional Conductors"Molecular Crystals and Liquid Crystals. 376. 53-58 (2002)
[Publications] M.Mori, K.Yonemitsu: "Optical Conductivity for Possible Ground States of Dimerized Two-Band Pd(dmit)_2 Salts"Molecular Crystals and Liquid Crystals. 376. 141-146 (2002)
[Publications] M.Kuwabara, K.Yonemitsu: "Optical Excitations in XMMX Monomers and MMX Chains"Molecular Crystals and Liquid Crystals. 376. 251-256 (2002)
[Publications] K.Yonemitsu, M.Kuwabara, N.Miyashita: "Variation Mechanisms of Ground-State and Optical Excitation Properties in Quasi-One-Dimensional Two-Band Electron Systems"Molecular Crystals and Liquid Crystals. 379. 467-471 (2002)
[Publications] M.Mori, K.Yonemitsu: "Charge Ordering Patterns and Their Excitation Spectra in Two-Dimensional Charge-Transfer Compounds"Molecular Crystals and Liquid Crystals. 380. 209-213 (2002)
[Publications] M.Kuwabara, K.Yonemitsu: "Strong Commensurability Effect on Metal insulator Transition in (DCNQI)_2Cu"Molecular Crystals and Liquid Crystals. 380. 257-261 (2002)
[Publications] K.Yonemitsu: "Finite-Temperature Phase Diagram of Mixed-Stack Charge-Transfer Complexes"Journal of Physics and Chemistry of Solids. 63. 1495-1499 (2002)
[Publications] J.Kishine: "Underlying SU(2) Gauge Structure and Hidden Staggered Flux State in the Lightly Doped Spin Liquid"Journal of Physics and Chemistry of Solids. 63. 1559-1562 (2002)
[Publications] M.Kuwabara, K.Yonemitsu, H.Ohta: "Spin Solitons in the Alternate Charge Polarization Background of MMX Chains"EPR in the 21st Century. 59-62 (2002)
[Publications] 岸根順一郎: "低次元強相関電子系における次元クロスオーバーと相転移-電子系繰り込み群ミニマム-"物性研究. 79. 502-530 (2002)

2002 Fiscal Year Annual Research Report

低次元分子性導体の電荷秩序と絶縁機構、光誘起非線型ダイナミクス

Principal Investigator

米満 賢治 岡崎国立共同研究機構, 分子科学研究所, 助教授 (60270823)

Research Products

[Publications] K.Yonemitsu: "Quantum and Thermal Charge-Transfer Fluctuations for Neutral-Ionic Phase Transitions in the One-Dimensional Extended Hubbard Model with Alternating Potentials"Physical Review B. 65. 085105 (2002)

[Publications] K.Yonemitsu: "Lattice and Magnetic Instabilities near the Neutral-Ionic Phase Transition of the One-Dimensional Extended Hubbard Model with Alternating Potentials in the Thermodynamic Limit"Physical Review B. 65. 205105 (2002)

[Publications] K.Yonemitsu: "Collective Excitations and Confinement in the Excitation Spectra of the Spinless Fermion Model on a Ladder"Physical Review B. 66. 035121 (2002)

[Publications] J.Kishine, K.Yonemitsu: "Dimensional Crossovers and Phase Transitions in Strongly Correlated Low-Dimensional Electron Systems : Renormalization-Group Study"International Journal of Modern Physics B. 16. 711-771 (2002)

[Publications] K.Yonemitsu: "Variation of Excitation Spectra in Mixed-Stack Charge-Transfer Complexes"Phase Transitions. 75. 759-767 (2002)

[Publications] N.Miyashita, M.Kuwabara, K.Ybnemitsu: "Domain-Wall Dynamics after Photoexcitations near Neutral-Ionic Phase Transitions"Phase Transitions. 75. 887-893 (2002)

[Publications] J.Kishine, P.A.Lee, X-G Wen: "Signature of the Staggered Flux State around a Superconducting Vortex in Underdoped Cuprates"Physical Review B. 65. 064526 (2002)

[Publications] K.Yonemitsu: "Intra-and Inter-Chain Excitations near a Quantum Phase Transition in Quasi-One-Dimensional Conductors"Molecular Crystals and Liquid Crystals. 376. 53-58 (2002)

[Publications] M.Mori, K.Yonemitsu: "Optical Conductivity for Possible Ground States of Dimerized Two-Band Pd(dmit)_2 Salts"Molecular Crystals and Liquid Crystals. 376. 141-146 (2002)

[Publications] M.Kuwabara, K.Yonemitsu: "Optical Excitations in XMMX Monomers and MMX Chains"Molecular Crystals and Liquid Crystals. 376. 251-256 (2002)

[Publications] K.Yonemitsu, M.Kuwabara, N.Miyashita: "Variation Mechanisms of Ground-State and Optical Excitation Properties in Quasi-One-Dimensional Two-Band Electron Systems"Molecular Crystals and Liquid Crystals. 379. 467-471 (2002)

[Publications] M.Mori, K.Yonemitsu: "Charge Ordering Patterns and Their Excitation Spectra in Two-Dimensional Charge-Transfer Compounds"Molecular Crystals and Liquid Crystals. 380. 209-213 (2002)

[Publications] M.Kuwabara, K.Yonemitsu: "Strong Commensurability Effect on Metal insulator Transition in (DCNQI)_2Cu"Molecular Crystals and Liquid Crystals. 380. 257-261 (2002)

[Publications] K.Yonemitsu: "Finite-Temperature Phase Diagram of Mixed-Stack Charge-Transfer Complexes"Journal of Physics and Chemistry of Solids. 63. 1495-1499 (2002)

[Publications] J.Kishine: "Underlying SU(2) Gauge Structure and Hidden Staggered Flux State in the Lightly Doped Spin Liquid"Journal of Physics and Chemistry of Solids. 63. 1559-1562 (2002)

[Publications] M.Kuwabara, K.Yonemitsu, H.Ohta: "Spin Solitons in the Alternate Charge Polarization Background of MMX Chains"EPR in the 21st Century. 59-62 (2002)

[Publications] 岸根順一郎: "低次元強相関電子系における次元クロスオーバーと相転移-電子系繰り込み群ミニマム-"物性研究. 79. 502-530 (2002)

米満賢治岡崎国立共同研究機構, 分子科学研究所, 助教授 (60270823)