Nanoscale phenomena in ferroelectric thin films

This paper reviews recent progress in our group in the area of thin film ferroelectrics. Specific focus is on nanoscale phenomena and relaxation dynamics in model thin films using voltage modulated scanning force microscopy. Using this technique we show the 3 dimensional reconstruction of the polarization vector in lead zirconate titanate(PZT) thin films. Secondly the time dependent relaxation of remanant polarization in epitaxial PZT ferroelectric thin films, containing a uniform 2-dimensional grid of 90° domains (c-axis in the plane of the film), has been investigated extensively. The 90° domain walls preferentially nucleate the 180° reverse domains during relaxation. Relaxation occurs through the nucleation and growth of reverse 180° domains, which subsequently coalesce and consume the entire region as a function of relaxation time. The kinetics of relaxation is modeled through the Johnson-Mehl-Avrami-Kolmogorov approach with a decreasing driving force. In addition we also present results on investigation of the relaxation phenomenon on a very local scale, where pinning and bowing of domain walls has been observed. © 2002 Taylor & Francis.