Landau-Khalatnikov Switching Kinetics in the Ferroelectric Copolymer Nanostructures

Abstract

In 1994 the first ultrathin Langmuir-Blodgett (LB) ferroelectric films were prepared from ferroelectric vinylidene fluoride and trifluoroethylene copolymer P(VDF-TrFE) [1]. It was shown that ferroelectricity exists even in two monolayers [2]. Later was shown, that these LB ferroelectric films do not reveal the critical size and ferroelectricity and polarization switching exist even in one monolayer with thickness 5 Å [3]. These films show typical phase transition of the first order with Curie temperature and phase transition temperature, which do not depend on the film thickness in the interval 1–30 ML [2, 3, 4, 5]. In contrast with usual well-known thick ferroelectric copolymer films, prepared by the spinning method, the Langmuir-Blodgett films do not contain amorphous phase and show perfect crystal structure of orthorhombic (or monoclinic) symmetry. Recently were obtained the experimental evidence of the existence of ferroelectricity in the perovskite films with thickness 1.2–5 nm [6, 7]. In this paper we show interesting peculiarities in switching kinetics of the ultrathin ferroelectric copolymer films.