Influence of Geometry on Domain Wall Dynamics in Permalloy Nanodevices

Abstract

We perform magnetoresistance (MR) and magneto-optical Kerr effect (MOKE) measurements to experimentally track magnetic domain wall (DW) pinning/depinning process in L-shaped Permalloy nanostructures of different geometries (i.e., square/round corner and absence/presence of circular disks) with widths in the range 75-400 nm. With MR and MOKE measurements being in a good quantitative agreement, we demonstrate that the field interval between pinning and depinning events increases with reduction of the nanowire width. In addition, the DW pinning/depinning behavior is geometry dependent, where round corners break the symmetry in the device orientation with respect to the field. The interpretation of experimental results is supported by micromagnetic simulations.