Depolarizing a ferroelectric film by ac fields of diminishing amplitude

In this paper, we demonstrate that a sol-gel-derived lead zirconate titanate film can be depolarized by the application of ac fields of diminishing amplitude, and we explain the phenomenon based on the concept of the Preisach model. The amplitude of the ac fields is decreased from 19.5 MV/m to 0.2 MV/m in eight steps. The observed piezoelectric coefficient of the film decreases after each step and finishes with almost the same value as that of an as-deposited film. Our results also reveal the existence of a distribution of coercive fields in the microdomains (Preisach dipolar units), and that the P–E loop of each microdomain is shifted by interaction fields so that the magnitudes of its switch-up and switch-down fields are not necessarily the same.