IMAGING MAGNETIC-CHARGES WITH MAGNETIC FORCE MICROSCOPY

An alternative interpretation of the contrast in magnetic force micros copy images is proposed. The new approach is based on rewriting the in teraction energy between tip and sample as a convolution of the scaler potential of the tip field with the magnetic ''charges'' of the sampl e. The second derivative of the scalar potential with respect to the t ip-sample distance has to be inserted to obtain the MFM image in the f orce gradient mode. By demonstrating the potential of conventional tip geometries to be sharply localized in particular for the mentioned de rivative we show that magnetic force microscopy is in the weak interac tion limit effectively a method for the high resolution observation of magnetic charges. The virtual identity of a simulated MFM image deriv ed from the numerically calculated stray field, and the corresponding charge image demonstrates the validity of the new approach.