Magnetic force microscopy: techniques and applications

This talk will review the techniques and applications of magnetic force microscopy (MFM). Magnetic force microscopy is a relatively new technique for observing magnetic microstructure on surfaces. Magnetic information is acquired by sensing the force acting on a sharp magnetic tip due to the magnetic field emanating from the sample. The magnetic tip is attached to a weak cantilever spring and the interaction force causes both a small deflection of the cantilever and a frequency shift of the cantilever's mechanical resonance frequency. Either of these effects can be used form MFM images. MFM images are formed by sensing one of these two effects while scanning the tip relative to the sample in a raster pattern. In our apparatus, the cantilever motion is detected using a fiber-optic interferometer. Shift in resonant frequency is detected directly using a sensitive frequency demodulation technique.