Multi-resonances behavior of Ni nanobelt/paraffin composites at microwave frequencies

Ni nanobelts are synthesized through a facile hydrothermal method to form magnetic composites for high frequency applications. Four resonance peaks of the relative complex permeability illustrate the multi-resonance behavior in Ni nanobelt/paraffin composites in a frequency range of 2-18 GHz. The resonance absorption characteristics are analyzed by fitting the permeability spectrum with the well-known Landau-Lifshitz-Gilbert (LLG) equation and Maxwell-Garnett mixing rule. Unlike previous studies, LLG equation has been deduced on account of the random distribution of Ni nanobelts in paraffin matrix first, and then applied for data fitting and resonance identification. Correspondingly, the first band is attributed to natural resonance, while the other three bands are considered to originate from non-uniform exchange resonance. (C) 2012 Elsevier B.V. All rights reserved.