AFM & MFM
In atomic force microscopy an atomically sharp tip is scanned above the surface of a sample in a contact, or non contact mode. A feedback mechanism controls a piezoelectric driver that adjusts the height of the tip as it is being scanned across the surface. By monitoring the z coordinate of the tip as a function of its x and y coordinates on the surface one can reconstruct the topography of the surface. All this is of course be computer controlled. Once the z versus x and y data has been acquired software is necessary to plot the surface in 3D, or extract roughness parameters and other relevant information.
In magnetic force microscopy (MFM) a ferromagnetic tip is used. The tip is scanned in non-contact mode and the magnetic domains in the sample exert forces on the tip. By monitoring the tip's response to the surface as a function of x and y, we can reconstruct the magnetic surface features. Interestingly, the magnetic features do not necessarily correpond to the physical surface features.