MAGNETIC-RESONANCE FORCE MICROSCOPY WITH A PERMANENT-MAGNET ON THE CANTILEVER

When the variation of the bias field is on the order of a few hundred gauss, permanent magnetic microparticles of Nd2Fe14B (NdFeB) mounted o n atomic force microscopy (AFM) cantilevers generate much smaller nonr esonance (NR) signals in the magnetic resonance force microscopy (MRFM ) spectra than most soft magnetic thin films. However, the interaction s of the NdFeB particle with the bias field cause an undesirable varia tion of the cantilever resonance frequency with changing bias field, O ur model indicates the importance of minimizing the polarized moment o f the magnetic tip and ensuring that the applied fields employed in th e MRFM experiment be highly uniform.