Scanning force microscopy and near-field scanning optical microscopy of ferroelectric and ferroelastic domain walls

Abstract

In this contribution polarization sensitive modes of scanning force microscopy (SFM) and near-field optical microscopy (NSOM) are illustrated focussing on the aspect of domain wall resolution in ferroelectric, ferroelastic, and charged domain walls. For c-domain inspection both friction force and dynamic force microscopy (DFM) are suitable, while the 3-dimen-sional polarization distribution from mixed a-c domains is obtained with voltage modulated SFM only. From such measurements, the smallest domain wall width of 8 nm was determined for 180° domain walls separating twin domains in ferroelectric tri-glycine crystals. Domain wall mapping of ferroelectric BaTiO₃ ceramics first results in a 25 nm width for ferroelastic domain walls. Second the effective crystallographic orientation of individual ferroelectric grains was deduced with respect to the sample normal, down to a 2° angular resolution. Furthermore, non-contact DFM measurements in ultra-high vacuum are able to resolve ferroelectric surfaces down to the atomic scale.