Effects of layering on the magnetostatic interactions in microstructures of CoxCu1-x/Cu nanowires

Arrays of electrodeposited CoCu/Cu multilayered nanowires have been characterized by ferromagnetic resonance and magnetometry measurements in order to study the effect of the dipolar interactions on the effective anisotropy field as a function of the magnetic and nonmagnetic layer thicknesses. Breaking the continuous cylinder geometry results in a reduction of the effective anisotropy field, which can be modified over a large range of values starting from 7 kOe in the case of nonlayered continuous nanowires down to nearly zero for the thinnest magnetic layers. An analytical model is presented to describe the magnetostatic interactions between magnetic layers and their effect on the total anisotropy field which shows a very good agreement with the experiments. Moreover, the model allows generalizing the description of the effective magnetostatic field as a function of the aspect ratio of both the magnetic and the nonmagnetic layers for multilayered nanowires of any combination of materials. A general anisotropy diagram is presented that describes the geometrical conditions required to obtain an easy axis parallel or perpendicular to the wire axis, thus providing a guide for the engineering and fine-tuning of the magnetic properties of these systems.