Capacitive distance control for measuring particulate magnetic media with magnetic force microscopy

It is challenging to precisely image magnetic structures in a context of pronounced topography. Tapping mode techniques have been developed to provide a practical solution to the need for magnetic characterization in these situations. By successively scanning the topography of the sample and its magnetic signal on a line-by-line basis, the sample's inherent topography and most dust contamination can be dealt with, constituting a convenient method for the study of e.g. patterned media, or other small structures. But as research and development push the relevant dimensions downward, higher sensitivity and spatial resolution are required of the measurement. It thus becomes necessary to move to vacuum, whereby the cantilever sensitivity is increased and adhered water layers can be removed. Vacuum operation also facilitates low temperature measurements, which generally present stability advantages apart from the possibility of applying large magnetic fields. The quantitative evaluation of measurement data introduces a further constraint on the measurement, that the tip must not be modified between measurements.