Magnetic imaging based on tunneling-stabilized, scanned-probe microscopies

We have modified the scanning tunneling microscopy (STM) method to do magnetic force microscopy (MFM) using a compliant, magnetic tunneling tip in place of the usual rigid STM tip. This method, referred to as tunneling-stabilized, magnetic force microscopy or TSMFM, is different from conventional MFM based on atomic-force-microscopy (AFM). Conventional MFM employs a displacement detector to measure the motion of the magnetic cantilever (see Fig. 1). TSMFM, on the other hand, operates in the usual STM sense with a flexible tunneling tip. This means that the TSMFM images show magnetic forces on the tip as well as topography. TSMFM images compare favorably with conventional MFM images as well as other types of magnetic imaging techniques including Bitter patterns, Lorentz microscopy, electron holography, or scanning electron microscopy with polarization analysis (SEMPA). Depending on the instrumentation, these methods can resolve magnetic features with sub-micrometer resolution, whereas methods based on STM or AFM have resolutions as good as 20 nm with the prospect of breaking the nanometer barrier.