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 Nd/sub 2/Fe/sub 14/B (NdFeB) mounted on atomic force microscopy (AFM) cantilevers generate much smaller nonresonance (NR) signals in the magnetic resonance force microscopy (MRFM) spectra than most soft magnetic thin films. However, the interactions of the NdFeB particle with the bias field cause an undesirable variation of the cantilever resonance frequency with changing bias field. Our model indicates the importance of minimizing the polarized moment of the magnetic tip and ensuring that the applied fields employed in the MRFM experiment be highly uniform.