Differentiating 180° and 90° switching of ferroelectric domains with three-dimensional piezoresponse force microscopy

Three-dimensional (3D) piezoresponse force microscopy is applied in order to differentiate 90° and 180° domain switching in ${\mathrm{PbTiO}}_3$ (PTO) thin films. The 3D domain configuration is recorded both statically, revealing the surface crystallographic orientation of PTO films on the nanometer scale, and dynamically by simultaneously mapping the in-plane and out-of-plane hysteresis loops. We show that exclusively 180° switching occurs, also switching only half of the grain volume.