セミナー情報

第56回 原研・兵県大合同コロキウム

日時: 平成21年3月10日(火) 14:00〜
Date and time: 10th Mar. (Tue.) 14:00〜
場所: SPring-8, 萌光館
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)
Abstract:

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.