Asymmetric nanoscale switching in ferroelectric thin films by scanning force microscopy

Scanning force microscopy (SFM) has been used to perform nanoscale studies of the switching behavior of Pb(Zr, Ti)O-3 thin films via the direct observ ation of their domain structures. The study revealed a significant asymmetr y of a switching pattern which is a function of the voltage polarity and or iginal domain structure of individual grains. The phenomenon of asymmetric switching is attributed (1) to the presence of an internal built-in electri c field at the bottom interface and (2) to the mechanical stress exerted by the SFM tip. The former effect results in incomplete 180 degrees switching , while the latter effect leads to a 90 degrees rotation of the polarizatio n vector. The resulting shear stress deformation of the grain underneath th e tip combined with the applied field effect propels polarization reversal in the adjacent grains. (C) 2001 American Institute of Physics.