Edge defects inducing asymmetric transverse domain walls created in Ni₈₀Fe₂₀ nanowires

Abstract

Polycrystalline permalloy nanowires with different widths were studied by means of a Lorentz microscope associated with micro-magnetic simulations. Each nanowire was designed to create a single head-to-head transverse domain wall. Edge defects at the long edges of those nanowires were incrementally controlled. Therein, a single pixel at different positions along the nanowire edges was removed. The horizontal nanowires were rotated with different angles, i.e. +/-5o, +/-10o, +/-30o and +/-45o, to produce a certain level of the edge roughness. Some curved nanowires with different widths were also designed, simulated and patterned. Lorentz images of those curved nanowires were recorded. The asymmetric levels of such created walls were measured and correlated to our wall phase diagram. The obtained results showed that the edge defects created along either side of a nanowire strongly induces the asymmetric level of a transverse domain wall.

Surface Roughness Effects on Magnetic Properties and Switching Mechanism in Iron Nanowires

“…Magnetic behavior studies of elongated permalloy and Co nanostructures show that when the ends of particle are asymmetrical the nucleation starts at only one of the ends and DW propagates then along the long axis of the structure [37], which is similar to the structures observed in simulations of rough surfaces (see Figure 4b). Experimental study of permalloy nanowires show that edge roughness may also affect the TDW degree of asymmetry, which may alter along the nanowire, as the result of different local spin configurations at the rough edges [39,42].…”