Single layer and multilayer tip coatings in magnetic force microscopy

Interactions between the imaging tip and the sample in magnetic force micro scopy (MFM) have been investigated by studying the magnetic microstructure of a range of epitaxial garnet films. Etched silicon cantilever probes, coa ted with CoPt alloy films and Co/Pt multilayers, provided a range of MFM pr obes for this study. Resonant torque magnetometry was used to characterize their magnetic properties. Phase change images were found to vary considera bly in terms of relative "domain volumes'' at the surface depending on whic h probe was used. Decreasing the moment of the alloy coated tips by using t hinner layers reduces the "magnetizing'' interaction of the tip field but a lso reduced the signal to noise ratio. By coating the tip with a multilayer a good signal to noise ratio could be obtained with very little interactio n. Force-distance curves were used to study the response of the tips at var ious lift heights. The tips coated with alloy films gave a significant decr ease in signal to noise ratio as the lift height increased whereas the mult ilayer tips maintained a signal which varied little with lift height. (C) 1 999 American Institute of Physics. [S0021-8979(99)79008-0].