Influence of adsorbed surface layer on domain growth in the field produced by conductive tip of scanning probe microscope in lithium niobate

The results of investigation of the single domain growth in electric field applied by conductive tip of the scanning probe microscope in thin plates of lithium niobate (LiNbO3) crystals doped with MgO after various surface preparations and at various ambient conditions are presented. It has been shown that the sizes of the produced domain can exceed by several orders of magnitude the value of the tip curvature radius. The observed effect has been explained taking into account the existence of the conductive adsorbed surface layer in all experimental conditions. We have demonstrated that the domain growth decelerates with decreasing of the layer conductivity. The existence of the conductive adsorbed surface layers drastically changes the spatial distribution of electric field. In addition to strongly localized electric field, just in the vicinity of the tip there exists the field component remaining homogeneous over the distance exceeding the radius of any experimentally produced domain. The crucial role of the conductive properties of the adsorbed surface layers on the screening of the depolarization field has been revealed. Within proposed approach the domain growth is controlled by the current in the external circuit including the surface layer with low conductivity. The proposed model allows us to explain time and field dependences of the domain size for various types of surface treatment. (C) 2011 American Institute of Physics. [doi:10.1063/1.3624798]