Force-microscopy contrast mechanisms in ferroelectric domain imaging

Contrast mechanisms for the detection of antiparallel domains in ferroelectric materials such as triglycine sulfate are investigated in the dynamic contact electrostatic force microscope. The domain contrast exhibits strong dependence on voltage modulation frequency, which is explained with the excitation of resonant modes of the cantilever in contact conditions. Phenomena such as contrast enhancement, inversion, and nulling are detected and accounted for with a simple model for the tip-sample interaction. The model includes 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.