MFM imaging of patterned permalloy elements under an external applied field

The magnetization process of micron-sized permalloy elements submitted to in-plane magnetic fields is analyzed by means of magnetic force microscopy (MFM). Depending on the magnetic history of the sample and on the value of the applied field, high remanence domain structures (the so-called S- and C-states) as well as flux closure configurations (Landau and diamond patterns) are observed. Perturbations induced by the MFM tip are found, and the results are discussed with the help of micromagnetic simulations.