Electronic Ferroelectricity in a Molecular Crystal with Large Polarization Directing Antiparallel to Ionic Displacement
Electronic Ferroelectricity in a Molecular Crystal with Large Polarization Directing Antiparallel to Ionic Displacement
复制标题
DOI：
10.1103/physrevlett.108.237601
复制
发表时间：
2012-06-04
影响因子：
8.6
通讯作者：
Tokura, Yoshinori
中科院分区：
文献类型：
--
作者：
Kobayashi, Kensuke;Horiuchi, Sachio;Tokura, Yoshinori
6.3 μ C cm(-2)的铁电极化是由中性到离子转变引起的，电子供体四硫富瓦烯(TTF)和受体对四氯苯醌(CA)的非极性分子不完全电离至+/-0.60e并沿着分子堆积链二聚化。我们发现铁电特性是由分子间电荷转移决定的，而不是分子上静点电荷的简单位移。观察到的绝对结构构型的极化和极化效应可以用电子铁电性来解释，它不仅表现出与离子位移相反的极性，而且将极化增强到点电荷模型的20倍以上。
Ferroelectric polarization of 6.3 mu C cm(-2) is induced by the neutral-to-ionic transition, upon which nonpolar molecules of electron donor tetrathiafulvalene (TTF) and acceptor p-chloranil (CA) are incompletely ionized to +/-0.60e and dimerized along the molecular stacking chain. We find that the ferroelectric properties are governed by intermolecular charge transfer rather than simple displacement of static point charge on molecules. The observed polarization and poling effect on the absolute structural configuration can be interpreted in terms of electronic ferroelectricity, which not only exhibits antiparallel polarity to the ionic displacement but also enhances the polarization more than 20 times that of the point-charge model.