Аннотация

Two-dimensional (2D) ferroelectricity and 2D ferroelectric-paraelectric phase transitions are experimentally studied, for the first time, by means of optical second harmonic generation (SHG) in ultrathin Langmuir-Blodgett (LB) films of vinylidene fluoride with trifluoroethylene. The temperature dependence of the SHG intensity confirms the existence of two types of 2D ferroelectric-paraelectric phase transition: the first one in the topmost layer of LB films and the other, almost thickness independent, in the bulk of ferroelectric LB films. (C) 2000 Elsevier Science B.V. All rights reserved.