Polarization reversal anti-parallel to the applied electric field observed using a scanning nonlinear dielectric microscopy

Ultrahigh-density storage devices consisting of poling reversed nanodots are examined using a scanning nonlinear dielectric microscope (SNDM). By using the SNDM, real-time observation of the poling direction was attempted and an unexpected phenomenon was discovered. For lithium tantalite films thicker than 350 nm, poling directions were aligned anti-parallel to the poling electric field. The critical thickness is thought to be dependent on the material properties, the probe radius, the applied voltage and the pulse duration. This anti-parallel poling phenomenon disagrees with previous poling reversal mechanisms from the conventional plate capacitor model. At present, the reason for and details of anti-parallel poling reversal are unclear, but may be related to the concentrated electric field near the cantilever. (C) 2004 American Institute of Physics.