Observation of ring shaped domain patterns using a scanning nonlinear dielectric microscopy

Unexpected ring shaped domain patterns were occasionally observed when ferroelectric nano-domain dots are formed by a voltage pulse application to the ferroelectric thin film using an electro conductive tip. In this study, we observed a real-time polarization reversal to understand such a variety of nano-domain formation processes. As a result, the ring shaped domain patterns were found to be related to the anti-parallel polarization reversal. Furthermore, by comparing the results of the congruent lithium tantalate to that of stoichiometric lithium tantalate, the mechanism of anti-parallel polarization reversal was suggested to link to the lattice vacancy of a specimen.