PARAMAGNETIC AND FERROMAGNETIC-RESONANCE IMAGING WITH A TIP-ON-CANTILEVER MAGNETIC-RESONANCE FORCE MICROSCOPE

A magnetic resonance force microscope with a ''tip-on-cantilever'' con figuration was used to compare imaging characteristics of paramagnetic and ferromagnetic samples. Three-dimensional electron paramagnetic re sonance (EPR) imaging of diphenylpicrylhydrazil (DPPH) particles was a ccomplished by scanning the sample in two dimensions while stepping an external field. The EPR force map showed broad response reflecting th e size and shape of the sample, allowing a three-dimensional real-spac e magnetization image to be successfully reconstructed. In contrast to the EPR case, ferromagnetic resonance imaging of a micron-scale yttri um iron garnet sample showed no significant line broadening despite th e strong field gradient (similar to 10 G/mu m). Two-dimensional force maps revealed spatial dependence of magnetostatic and magnetoelastic m odes. (C) 1998 American Institute of Physics.