Dynamics of surface-coupled microcantilevers in force modulation atomic force microscopy - magnetic vs. dither piezo excitation.

Force modulation atomic force microscopy is widely used for mapping the nanoscale mechanical properties of heterogeneous or composite materials using low frequency excitation of a microcantilever scanning the surface. Here we show that the excitation mode - magnetic or dither piezo, has a major influence on the surface-coupled microcantilever dynamics. Not only is the observed material property contrast inverted between these excitation modes but also the frequency response of the surface-coupled cantilever in the magnetic mode is near-ideal with a clear resonance peak and little phase distortion thus enabling quantitative mapping of the local mechanical properties. [ABSTRACT FROM AUTHOR]