| Project/Area Number |
15540354
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics II
|
|---|
| Research Institution | Institute for Molecular Science (2004-2006)
Okazaki National Research Institutes (2003) |
|---|
Principal Investigator |
YONEMITSU Kenji Institute for Molecular Science, Department of Theoretical Studies, Associate Professor, 理論分子科学研究系, 助教授 (60270823)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YAMASHITA Yasufumi Institute for Molecular Science, Department of Theoretical Studies, Research Associate, 理論分子科学研究系, 助手 (50390646)
岸根 順一郎 九州工業大学, 工学部, 助教授 (80290906)
|
|---|
| Project Period (FY) |
2003 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
|
|---|
| Keywords | Organic Charge-Transfer Salt / Ionic-Neutral Phase Transition / Quantum Paraelectric Phase / Quantum Phase Transition / Photoinduced Phase Transition / Charge Order Melting Transition / Insulator-Metal Transition / Coherent Phonon / 量子常誘電体 / バレット公式 / 量子BEGモデル / 逆スピンパイエルス転移 / 巨大誘電応答 / チタン酸化物 / 量子イジングモデル / ハロゲン架橋金属錯体 / 非線型光学応答 / 超高速緩和現象 / 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 / 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 |
In mixed-stack charge-transfer DMTTF-QBr_nCl_<4-n> complexes, the neutral-ionic phase transition takes place at zero temperature if the composition n and pressure are tuned. From the pressure dependence of the transition temperature and the paraelectric behavior following the Barrett formula, it is regarded as a quantum phase transition. Quantum paraelectricity generally appears when quantum fluctuations destroy the ordering of local polarizations. In the above materials, local polarizations appear in the ionic phase, but the quantum paraelectricity appears in the neutral phase only. To consider its origin, we represent polarizations in the ionic phase by Sz=+1/-1, a neutral site by Sz=0, and obtain mean-field solutions in the quantum Blume-Emery-Griffiths model. The quantum tunneling term leads to charge-transfer fluctuations, which cause partial ionicity in the neutral phase. As a consequence, the dielectric permittivity follows the Barrett formula in the neutral phase near the quant
… More
um critical point.
In order to study consequences of the differences between the ionic-to-neutral and neutral-to-ionic transitions in the one-dimensional extended Peierls-Hubbard model with alternating potentials for the TTF-CA complex, we introduce a double pulse of oscillating electric field in the time-dependent Schrodinger equation and vary the interval between the two pulses as well as their strengths. When the dimerized ionic phase is photoexcited, the interference effect is clearly observed owing to the coherence of charge density and lattice displacements. The two pulses constructively interfere with each other if the interval is a multiple of the period of the optical lattice vibration, while they destructively interfere if the interval is a half-odd integer times the period, in the processes toward the neutral phase. Meanwhile, when the neutral phase is photoexcited, the interference effect is weakly observed, where the photoinduced lattice oscillations are considerably incoherent due to random phases. Less
|
