Nanoscale polarization relaxation kinetics in polycrystalline ferroelectric thin films

Abstract

We report on the nanoscale kinetics of ferroelectric domain wall motion in polycrystalline ferroelectric thin films. High-resolution piezoresponse force microscopy is employed to investigate the changes that occur at the domain wall surface during the polarization relaxation process. 50×50nm2 domain images reveal that domain wall motion is a very jerky process. The domain wall motion shows two distinct cycles—one where it breaks into several segments to advance, following which it recombines to form a continuous surface. This “pinning-depinning” cycle continues throughout the relaxation process. A kinetic model based on the concept of domain wall mobility and a thermodynamic driving force is developed to explain this jagged motion.