Spatial characterization of the magnetic field profile of a probe tip   used in magnetic resonance force microscopy
  We have developed the experimental approach to characterize spatial distribution of the magnetic field produced by cantilever tips used in magnetic resonance force microscopy (MRFM). We performed MRFM measurements on a well characterized diphenyl-picrylhydrazyl (DPPH) film and mapped the 3D field profile produced by a Nd2Fe14B probe tip. Using our technique field profiles of arbitrarily shaped probe magnets can be imaged. 
E. Nazaretski, E. A. Akhadov, I. Martin, D. V. Pelekhov, P. C. Hammel,   and R. Movshovich