日本原子力研究開発機構 (JAEA) / 量子ビーム応用研究部門
放射光科学研究ユニット / 放射光量子シミュレーショングループ
|Date and time:||10th Mar. (Tue.) 14:00〜|
|Place:||SPring-8, "HOUKOUKAN" seminar room|
|Title:||Monte Carlo study of neutral-ionic transition in charge-transfer organic complexes|
|講演者:||加藤 岳生 氏 （東大物性研）|
|Speaker:||Prof. Takeo Kato (Institute for Solid State Physics, University of Tokyo)|
A charge-transfer type organic complex composed of two different molecules has attracted interest for a dew decades in the viewpoint of neutral-ionic transition, which is essentially a transition from a band insulator to a Mott insulator in a quasi-one-dimensional electron system with a half-filled band. Because the Mott phase usually involves the spin-Peierls instability, the low-temperature ionic phase shows ferroelectricity. Recently, this system has been revisited in the view of effective control of ferroelectricity through change of electronic states. In this talk, I will discuss the neutral-ionic transition starting with a microscopic model (an ionic-Hubbard model). By applying a quantum Monte Carlo technique and an inter-chain mean-field theory, the finite-temperature phase diagram of this system is determined numerically. I will compare the obtained phase diagram with experimental observation for TTF-CA, which is a typical charge-transfer complex.