Modelling of MFM images of 180 degrees and 90 degrees domain walls in iron films

We report symmetric and antisymmetric 180 degrees and 90 degrees domain walt structures in (100) iron films obtained by micromagnetic computer simulation and the force gradients experienced by a pyramidal tip coated with thin CoCr film scanning them at 50 nm altitude. The magnetic force gradient was obtained numerically as the second difference of the interaction energy of the magnetic tip and the sample for small vertical displacements. The results showed that by using a magnetic force microscope (MFM), it is very difficult to distinguish (i)S and C type 180 degrees domain walls in a thick iron film; and (ii) symmetric and asymmetric 90 degrees NBel domain walls. However, S and C 180 degrees domain walls can more readily be distinguished in thin magnetic films.