Theory of magnetic force microscope images

A model is presented for magnetic force microscope (MFM) images obtained with a ferromagnetic tip and a ferromagnetic sample. Results of calculations are compared to recent MFM experiments and show good agreement using known values for magnetic parameters characterizing tip and sample. The model describes a limit in resolution determined by the demagnetizing effect of tip and sample, predicts the appearance of a novel image artifact which is particularly observable in images of narrow domains of reversed magnetization, and suggests an explanation for the observed contrast between regions of opposite magnetization.