Magnetic Domain Wall Manipulation using MFM Probe

Magnetic force microscopy (MFM) has been applied to permalloy multistep-semicircular wires containing nearly-free magnetic domain walls (DWs). In this study, we investigated the effect of stray-magnetic fields from the probes in the MFM measurement using low-, medium-, and high-moment probes, which are coated by 12 nm-, 24 nm-, and 72 nm-thick CoPtCr films, respectively. By using the low-moment probe, the DW signal was clearly observed at the side of the wires, which is consistent with a micromagnetic simulation. By using the high and medium moment probes, in contrast, we observed complete and incomplete DW manipulations, respectively. These manipulation signals were found to be maximized immediately above the wire. These phenomena were analyzed by calculating the stray fields from the MFM probes. We also discussed the possibility of the controllable DW manipulation in terms of the stray fields and the MFM scanning sequences.