Domain Motion in Bismuth-Layer-Structured Ferroelectrics by Applying Electric Fields

Domain wall motion and polarization reversal time along the a–b plane in single crystals of various bismuth-layer-structured ferroelectrics (BLSFs) are described. Direct observation of domain wall motion by applying an electric field was performed using a polarizing microscope. By applying an electric field parallel to the domain walls, extinction of domain walls and production of new domain walls perpendicular to the former ones were observed. By applying an electric field at an angle of 45° from the domain walls, extinction of domain walls, in short, `poling', was observed. The process of domain wall motion was similar regardless of the kind of BLSF used. From the electric field dependence of the polarization reversal time, domain wall motion was found to be a forward one due to a nucleation mechanism. This motion was consistent with that observed directly using the polarizing microscope. The velocity of domain wall motion was dependent on the kind of BLSF used; the velocity was higher in BLSF with a large number of RO6 octahedra between bismuth layers.