Magnetization processes in two-dimensional arrays of iron nanowires

Abstract

Arrays of iron nanowires (NWs) obtained by template-assisted electrodeposition constitute a promising composite material characterized by a combination of high magnetization in the filler and perpendicular magnetic anisotropy. The properties of these composites arise from the interplay between the behavior of individual NWs and their magnetostatic interactions. In this study, we investigated NW arrays with identical wire diameters but varying spatial arrangements. Major hysteresis loops were studied under various field directions relative to the NW axis. Key parameters such as the slope of the magnetization curve, saturation magnetization, and coercive force were quantified. Additionally, FORC (First Order Reversal Curve) measurements were conducted with the field oriented longitudinally with respect to the NW, offering insights into the inhomogeneity of the demagnetizing field influenced by the NW array's configuration. In the sample with the highest NW density, we observed isotropic behavior of the effective demagnetizing field, and we proposed an explanation for this phenomenon using the effective media approach. Micromagnetic simulations revealed that the magnetic behavior of individual NWs with a 100 nm diameter can be described as an interchange between volumes characterized by vortex and uniform magnetization patterns. Calculations of the demagnetizing field using the effective medium model demonstrated excellent agreement with experimental data across arrays featuring different NW densities. Remarkably, the quantitative consistency of coercive field values obtained from micromagnetic simulations and experimental measurements in the range of angles from 0° to 45° for the studied samples underscores the structural homogeneity of the obtained NWs.