In this study, we have developed secondary resonance magnetic force microscopy (SR-MFM) for imaging alternating magnetic fields from a sample surface at the secondary resonant frequency of the magnetic cantilever at the same time as the topographic image. SR-MFM images of alternating magnetic fields diverging from the main pole in a driving perpendicular magnetic recording head are presented, and the divergence and convergence of the fields are discussed. The spatial resolution of SR-MFM is estimated to be 18 nm; this is 2.5 times smaller than that of conventional MFM. V

The surface topography and the distribution of stray magnetic flux density of Fe70Co30 are observed simultaneously by using scanning Lorentz force microscopy (SLFM). The SLFM images of the magnetic domain of Fe70Co30 have been observed repeatedly, and they were found to be unaffected by the surface roughness and friction force. As compared to the magnetic force microscopy image, it can be inferred that small stray magnetic flux loops were detected near the sample surface in the SLFM image.