Contrast mechanisms for the detection of ferroelectric domains with scanning force microscopy

We present a full analysis of the contrast mechanisms for the detection of ferroelectric domains on all (x, y and z) faces of bulk single crystals using scanning force microscopy. The experiments were carried out with hexagonally poled lithium niobate to ensure access to a well-defined domain structure on every crystal face. The domain contrast can be attributed to three different mechanisms: (i) the thickness change of the sample due to an out-of-plane piezoelectric response (standard piezoresponse force microscopy), (ii) the lateral displacement of the sample surface due to an in-plane piezoresponse and (iii) the electrostatic tip-sample interaction at the domain boundaries caused by surface charges on the crystallographic y- and z-faces. A careful analysis of the movement of the cantilever with respect to its orientation relative to the crystallographic axes of the sample allows clear attribution of the observed domain contrast to the driving forces.