Nanoscale imaging of domains and domain walls in periodically poled ferroelectrics using atomic force microscopy

We use the inverse piezoelectric effect for high-resolution imaging of artificially produced ferroelectric domains in periodically poled potassium titanium phosphate, $KTiOPO4,$ and lithium niobate, $LiNbO3,$ crystals using a modified atomic force microscope (AFM). By monitoring the vertical as well as the lateral deflection of the AFM tip, details of the domains and the domain walls were obtained at 1 nm resolution. With this approach we determine the domain wall width to be 20–80 nm for $KTiOPO4$ and about 150 nm for $LiNbO3.$ The above technique is of importance in tailoring ferroelectric crystals for frequency conversion of lasers and studies of domain walls in ferroelectric and its magnetic analogs.