Direct observation of domain dynamics in lead zirconate titanate thin films

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Abstract
We report observations of the ferroelectric domain structure in epitaxial lead zirconate titanate (PZT) ferroelectric thin films using piezoresponse microscopy. EpitaxialPZT films with a nominal composition of PbZr0.2Ti0.8O3were deposited onto single crystal SrTiO3 substrates by pulsed laser deposition, with an epitaxial layer of La-Sr-Co-O as the bottom electrode. By manipulating thefilm thickness, a uniform 2-dimensional grid of 90° domains (a-domains, i.e., c-axis in the plane of the film) has been induced. Our studies show that the polarization direction in the film is substantially preferentially oriented and that nucleation of reverse 180° domains occurs preferentially at 90° domain interfaces. Polarization reversal occurs through the nucleation and subsequent growth of “semicircular/elliptical” reverse domains, which subsequently consume the entire region as a function of reversal time. The reversal is seen to fit a stretched exponential.