Inhomogeneous nucleation and domain wall motion with Barkhausen avalanches in epitaxial PbZr0.4Ti0.6O3 thin films

Abstract

We investigated the ferroelectric (FE) domain nucleation and domain wall motion in epitaxial PbZr0.4Ti0.6O3 capacitors by using modified piezoresponse force microscopy with the domaintracing method. From time-dependent FE domain evolution images, we observed that defectmediated inhomogeneous nucleation occurred with a stochastic nature. In addition, we found that the number of nuclei N(t) was linearly proportional to log t, where t is the accumulated time of the applied pulse fields. The time-dependence of N(t) suggests a distribution of energy barriers for nucleation, which may determine the stochastic nature of domain nucleation. We also observed that the domain grew with consecutive Barkhausen avalanches and that the growth direction became anisotropic when the domain radius was larger than a critical radius of about 100 nm.