Angular Dependence of Magnetization Behavior in Ni81Fe19 Nanowires by Micromagnetic Simulations

Abstract

Nickel (Ni)-iron (Fe) alloy in the form of Ni81Fe19 (permalloy) is a widely used material in technological soft magnetic applications. Understanding the magnetization behavior in detail in such materials is substantial from both a scientific point of view and industrial demands. Therefore, the main purpose of the present article is to discuss the angular dependence of magnetization in Ni81Fe19 nanowires by micromagnetic simulation using the object-oriented micromagnetic framework (OOMMF) platform. These investigations have been implemented on different widths/thicknesses (T) up to 150 nm with an identical stretch of 1 µm. There was a reduction in the remanent magnetization by increasing the wire angle with respect to the magnetic field applied, which displayed excellent agreement with calculations performed theoretically. This was designated for the effect of shape anisotropy on behavior. The angular dependence of the switching behavior was analyzed and compared theoretically with the classical domain wall reversal models. The magnetic reversal for wires ≤30 nm was well defined by the uniform rotation of the Stoner–Wohlfarth model, whereas for nanostructures ≥50 nm was analyzed by the nonuniform rotation of the curling model. The critical thickness for the transition between these models was theoretically calculated and found to be around 30 ± 5 nm, which is in good agreement with the other findings presented in the literature using other materials of ferromagnetic wires. The micromagnetic spin structure was obtained instantaneously before and after switching events for relatively thick (150 nm) nanostructures at different angles, suggesting that the reversal is not as simple as predicted by the domain wall reversal of nonuniform rotation of the curling model.