Priority of domain wall pinning during the fatigue period in bismuth titanate ferroelectric thin films

Abstract

The switching current densities of pure Bi4Ti3O12 thin films were measured during a fatigue process. The peak switching current density and switching time decrease with the increase of switching cycles, which indicates a domain wall pinning effect by defects inside thin films. Through the fitting of the switching current density using the modified Kolmogorov-Avrami theory, it is found that the percentage of two-dimensional (2D) domain growth decreases during the fatigue period, which reveals that 2D domain growth has an absolute priority to be pinned compared with one-dimensional domain growth. The mechanism of the increased activation field during the fatigue process is briefly discussed based on the domain wall pinning effect. These results are of great importance in the switching kinetics and fatigue mechanisms in ferroelectric films.