Formation of 90° elastic domains during local 180° switching in epitaxial ferroelectric thin films

90degrees elastic domains were observed after local polings in epitaxial ferroelectric Pb(Zr0.2Ti0.8)O3 thin films via piezoresponse force microscopy. An area of internal stress arises under a conductive atomic force microscope tip due to the opposite signs of the converse piezoelectric effects in the switched domain and the unswitched films surrounding. The formation of 90degrees domains leads to the relaxation of the internal stress and stabilization of 180degrees domain after turning off the electric field applied by the tip. The criterion that formulates the necessary condition for realization of the relaxation mechanism is presented as well. (C) 2004 American Institute of Physics.