Forward Growth Of Ferroelectric Domains With Charged Domain Walls. Local Switching On Non-Polar Cuts

Forward domain growth representing one of the main stages of domain switching is studied for isolated domains and domain arrays appearing as a result of tip-induced switching on the non-polar cuts of lithium niobate crystals. Formation of the wedge-like domains with a high aspect ratio and charged domain walls is observed. The domain growth in the area with a negligible external field is considered in terms of the kinetic approach based on analogy with crystal growth. The domain wall motion by step generation and propagation of the charged kinks is discussed. It is proposed that the switching field contains the inputs of the external field produced by a biased scanning probe microscope tip, the depolarization field produced by charged kinks, and the screening fields. According to the simulation results of the field distribution, the forward growth is caused by the step generation near the tip and the kink propagation induced by the depolarization field produced by the kinks. Scanning with the biased tip creates self-assembled domain arrays with several modes of domain length alteration: doubling, quadrupling, and chaotic. The statistical characterization of the arrays proves their high ordering. The array is formed under the influence of the depolarization field produced by three neighboring domains. The proposed mechanism can be applied for forward domain growth during switching on the polar cuts as well. In this case, the steps on the domain wall are generated on the polar surface, whereas the domain elongates by kink motion in the field produced by the charged kinks.