Charge Order and Photoinduced Nonlinear Dynamics in Low-Dimensional Molecular Conductors

低维分子导体中的电荷有序和光致非线性动力学

基本信息

批准号：
12640361
负责人：
YONEMITSU Kenji
金额：
$ 2.37万
依托单位：
Okazaki National Research Institutes
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In (DCNQI)_2Cu, conductivity and magnetism are correlated through hybridization of π and d orbitals. In the insulator phase under high pressure, three-fold lattice distortion and paramagnetism coexist. Peierls and Mott mechanisms work cooperatively. Even the level difference between these orbitals is not optimal, self-doping takes place to stabilize this lattice-distorted phase. This fact is demonstrated by the exact diagonalization studies for a two-band Peierls-Hubbard model.In organic charge-transfer complex, TTF-CA, a transition takes place from the paraelectric neutral phase to the ferroelectric ionic phase at a low temperature or under high pressure. Photoexcitation also triggers the transition. The time-dependent Schrodinger equation is solved for an extended Peierls-Hubbard model with alternating potentials. Dynamics of charge density and lattice displacements from the ionic phase is studied to reproduce a threshold in phtoexcitation intensity. The Fourier analysis of the time- … More dependent ionicity clarifies the fast excitonic motion, the slow lattice vibration, and the even slower collective motion of neutral-ionic domain boundaries. Photoexcitation produces ionic domains with the opposite polarization to the initial one, by which the lattice order quickly decays. This is consistent with the faster evolution of the second harmonic generation than the photoreflectivity.In halogen-bridged binuclear metal complexes, various charge- and lattice-ordered phases appear depending on the ligand, halogen ion, and counter ion. The mechanisms of the respective electronic phases are investigated in Peierls-Hubbard models. Especially with iodine, platinum, and ligand pop, halogen ion, and counter ion. The mechanisms of the iodine, platinum, and ligand pop, there appear charge-density-wave (CDW) and chargepolarization (CP) phases. Photoexcitation within the hysteresis loop triggers a transition phase does not transfer charge among binuclear units at low energies, and does not grow CDW nuclei even at high energies. Less

在(DCNQI)_2Cu中，电导率和磁性通过π和d轨道的杂化相关联，在高压下的绝缘体相中，三重晶格畸变和顺磁性机制同时存在，甚至这些轨道之间的能级差也协同作用。不是最佳的，会发生自掺杂来稳定该晶格扭曲相，这一事实已通过两能带的精确对角化研究得到证明。 Peierls-Hubbard 模型。在有机电荷转移复合物 TTF-CA 中，在低温或高压下发生从顺电中性相到铁电离子相的转变，也会触发时间依赖性薛定谔转变。求解具有交变电势的扩展 Peierls-Hubbard 模型研究了离子相的电荷密度和晶格位移的动力学，以重现光激发的阈值。时间依赖性离子性的傅立叶分析阐明了快速激子运动、缓慢的晶格振动以及中性离子域边界的更慢的集体运动，产生了与初始极化相反的离子域，晶格顺序快速衰减，这与二次谐波产生比光反射性更快的演化是一致的。在卤素桥联的双核金属络合物中，各种电荷和晶格有序相的出现取决于配体、卤素离子和抗衡离子，在 Peierls-Hubbard 模型中研究了各个电子相的机理，尤其是碘、铂和配体 pop、卤素离子和抗衡离子机理。碘、铂和配体流行，在磁滞回线内出现电荷密度波（CDW）和电荷极化（CP）相。触发过渡相在低能量下不会在双核单元之间转移电荷，并且即使在高能量下也不会生长 CDW 核。