The effect of edge-roughness of magnetic nanowires on the degree of asymmetry in transverse domain walls

Abstract

We present a quantitative measurement of asymmetry in transverse domain walls created in magnetic nanowires using micro-magnetic simulation and experimental microscopy approaches. This aims to explore how to define the asymmetry of these walls. Transverse domain walls were simulated in straight permalloy nanowires. The measurement of asymmetry is described by means of the correlation between surface magnetization components and areas within each transverse domain wall. The simulation results show a clear trend of transformation between symmetry and asymmetry wall phases with an increase of nanowire-width. Curved nanowires with different widths were experimentally patterned by focused ion irradiation method. Measurements from Lorentz microscopy images indicate that the degree of asymmetry of the walls created in the curved nanowires is strongly affected by edge roughness of these nanowires. Results of the experiments and simulations in curved nanowires scatter around the trend of the simulation data for straight nanowires due to the effect of edge roughness. These findings would make a significant contribution to a new route-map of quantitative measurements for the transition from symmetric transverse domain walls to asymmetric ones and vice versa.