Force-microscopy contrast mechanisms in ferroelectric domain imaging

Contrast mechanisms for the detection of antiparallel domains in ferroelect ric materials such as triglycine sulfate are investigated in the dynamic co ntact electrostatic force microscope. The domain contrast exhibits strong d ependence on voltage modulation frequency, which is explained with the exci tation of resonant modes of the cantilever in contact conditions. Phenomena such as contrast enhancement, inversion, and nulling are detected and acco unted for with a simple model for the tip-sample interaction. The model inc ludes the effects of the viscoelastic sample response and confirms that the observed contrast features have to be attributed to the spectral response of the tip-sample junction.