Mechanism of Magnetization Reversal in Arrays of Multilayered Nanowires

The effect of the shape anisotropy and dipolar interactions between NiFe magnetic layers on the magnetization reversal of NiFe/Cu multilayered nanowire arrays electrodeposited into the nanopores of anodic aluminum oxide (AAO) templates with diameters of 35 nm has been studied. The magnetization reversal mechanism has been investigated from the magnetic hysteresis loops of NiFe/Cu nanowires, for various angles θ between the applied field and the nanowires axis. The magnetization reversal strongly depends on the variation of the aspect ratio (thickness/diameter) between NiFe and Cu layers. Based on the Aharoni´s model and the Stoner-Wohlfarth model, we calculated the coercive field (H_c) of multilayered nanowires, considering also the intra-nanowires interaction. The calculated results are in good agreement with the experimental ones even for thin NiFe layers, when the calculated results without considering the magnetostatic coupling between the adjacent ferromagnetic layers are unable to follow the experimental results. Additionally, the angular variation of the normalized remanence (M_r(θ)/M_s) for NiFe/Cu nanowires with various NiFe layers thickness was studied. The experimental H_c and M_r(θ)/M_s values were derived from the hysteresis loops.