Experimental study of internal fields and movement of single ferroelectric domain walls Original Research Article

We have made a direct and submicron scale measurement of the strain, internal electric field of single 180° domain walls in ferroelectric LiTaO3 using a collection mode Near-Field Scanning Optical Microscope. We unambiguously identify single domain walls by simultaneously recording nanometer scale topographic and optical images. The birefringence at the domain wall is used in the optical imaging. From the internal field structure we estimate the interface energy. We have also studied the pinning and movement of a single 180° domain wall under an uniform applied electric field. The domain wall was observed to curve between the pinning defects with a radius of curvature uniquely given by the material parameters and the applied electric field. The change in birefringence with applied field is related to the second order electro-optic and piezo-optic coefficients and is used to infer the orientation of the internal field.