Dependence of magnetization process in a Ni-Fe nanowire on the width of the nanowire

We investigated the dependence of the magnetization process in 30-nm-thick Ni-Fe nanowires on the width of the nanowire using the magnetic field sweeping (MFS) - magnetic force microscopy (MFM), which measures phase changes (stray field changes) using a MFM tip as a detector. The phase changes are dependent on the width of the nanowire; hysteresis loops of the phase and plateau areas of the phase are observed at local points for the widths between 100 - 600 nm, while local points, each, display the hysteresis loops of the phase and the valleys of the phase for the width of 800 nm. These results demonstrate that the dominant factor in the magnetization process of 30-nm-thick Ni-Fe nanowires changes from domain wall motion and domain wall pinning to domain wall motion with increasing the width of the nanowires.