Polarization-switching mechanisms for epitaxial ferroelectric Pb(Zr,Ti)O3 films

Epitaxial films have well-ordered lattice structures similar to single crystals but contain many defects such as dislocations, low-angle grain boundaries and strain. These kinds of defects can affect the switching properties of epitaxial films and are of interest for the application of the films to switching devices. We measured the polarization switching of epitaxial Pb(Zr0.4Ti0.6)O-3 (PZT) films with SrRuO3 electrodes, and tested the domain-wall motion with a piezoelectric force microscope. The switching behaviors of the epitaxial films followed the Kolmogorov-Avrami-Ishibashi model at various field regions. The piezoelectric measurement; showed that the domain-wall motion in the epitaxial PZT films seems to follow creep motion behavior, different from the limited domain-wall motion in polycrystalline PZT films, The frequency dependence of the coercive field (E-c) of the epitaxial PZT films was induced from the polarization switching data, and it showed f(1/12) dependence of E-c.