Vortex Domain Wall Pinning Probability in Nanowires of Various Widths

We report the results of a micromagnetic simulation of a vortex domain wall (VDW) dynamic pinning probability in 20 nm thick planar permalloy wires with triangular notches and widths of 100, 200, and 300 nm. The notches have a fixed depth ratio of 30%, which is depth divided by wire width. Both the wire width and the applied field influenced the dynamic VDW pinning probability and the pinning probability decreased as the wire width increased. We observed a pinned domain wall (DW) structure around the notches and defined two types of pinning states, transverse DW (TDW) pinning and VDW pinning. The 100 nm wide wire had more TDW pinning-type events than did the 200 and 300 nm wide wires. The 300 nm wide wire had the lowest number of TDW pinning-type events. These results were caused by different wire widths having different DW energy densities and different pinning potential energy landscapes. When the applied field was larger than the Walker field, the wide wires easily led to a complex VDW motion.