QUANTITATIVE MAGNETIC-FIELD MEASUREMENTS WITH THE MAGNETIC FORCE MICROSCOPE

We have developed a technique to quantitatively image the magnetic fie ld above a magnetic specimen using a modified magnetic force microscop e (MFM). The technique depends on the nonlinear response of a magnetic ally soft MFM tip to the sample field and to an externally applied fie ld, similar in principle to fluxgate magnetometry. We demonstrate the technique with high resolution, quantitative images of the magnetic fi eld above a sample of longitudinal recording media. The magnetic field resolution is on the order of 1 Oe, with sub-100 nm spatial resolutio n comparable to standard MFM techniques. (C) 1996 American Institute o f Physics.