Thickness-Dependence of the Coercive Field in Ferroelectrics
Abstract
For forty years researchers on ferroelectric switching have used the Kay-Dunn theory to model the thickness-dependence of the coercive field; it works surprisingly well, despite the fact that it is based upon homogeneous nucleation and a small-field expansion, neither of which is realized in thin films. Here we demonstrate that this result can be obtained from a more general Kolmogorov-Avrami model of (inhomogeneous) nucleation and growth. By including a correction to the switching field across the dielectric that includes Thomas-Fermi screening in the metal electrode, we show that our theory quantitatively describes the coercive fields versus thickness in several different families of ferroelectric (lead zirconate-titanate [PZT], potassium nitrate, and polyvinylidenefluoride [PVDF]) over a wide range of thickness (5 decades). This agreement is particularly satisfying in the case of PVDF, as it indicates that the switching kinetics are domain-wall limited down to 1 nanometer and thus require no new effects.
Cite
@article{arxiv.cond-mat/0206014,
title = {Thickness-Dependence of the Coercive Field in Ferroelectrics},
author = {P. Chandra and M. Dawber and P. B. Littlewood and J. F. Scott},
journal= {arXiv preprint arXiv:cond-mat/0206014},
year = {2007}
}