A comparison of the magnetic properties of Ni and Co nanowires deposited in different templates and on different substrates

Nickel (Ni) and cobalt (Co) nanowire arrays (NWs) grown by electrode position in porous nano-templates are studied by the ferromagnetic resonance (FMR) technique at room temperature (RT) by comparing the effects of template type (alumina and polycarbonate) and the deposition substrate (i.e., metallic back contact). The line-width and resonance field of the FMR spectra strongly depends on the orientation of the applied field direction. A model is developed to analyze the spectra in order to extract the magnetic parameters such as g-values, spin-spin relaxation times (T-2) and uniaxial an isotropy parameters. The experimental FMR spectra and their resonance field values were fitted using the imaginary part of magnetic susceptibility and a dispersion relation of magnetization, including the Bloch-Bloembergen type damping term. The easy axes of magnetization for all Ni and Co NWs were found to be perpendicular to the wire-axis. Surface spin modes have been observed only when pure Au was used as substrate. A discussion will be provided to explain the observed differences in terms of the anisotropic behavior and magnetic parameters of the NWs for different substrates and growth templates. (C) 2014 Elsevier B.V. All rights reserved.