Velocity of domain-wall motion during polarization reversal in ferroelectric thin films: Beyond Merz's Law

Abstract

The motion of domain walls (DWs) is critical to switching kinetics in ferroelectric (FE) materials. Merz's law, dependent only on the applied electric field, cannot explain recent experimental observations in FE thin films because these experiments showed that the DW velocity depends not only on the strength of the applied electric field but also on size of the reversal domain. In this paper, we derive a model to understand the dominant factors controlling the velocity of FE DWs. Our calculations reveal that the DW velocities are not only a function of the strength of the electric field but also decay exponentially with the increasing characteristic time of the measurement or the size of the growing domain. Our observations can naturally explain the gigantic variation reported in the literature, over 15 orders of magnitude, in the experimentally measured DW velocities and the formation of the stripe shape of FE domains.