Ferromagnetic resonance studies of nickel and permalloy nanowire arrays

Arrays of nickel and permalloy nanowires have been studied by ferromagnetic resonance for frequencies ranging from 10 MHz up to 40GHz using a micro-strip transmission line. Measurements of the transmission coefficient show intense resonance peaks which exhibit a pronounced dependence on the frequency-field values. The interplay between the angular-field resonance frequency and the material parameters has been studied in detail. It is shown that by changing the wire packing density, the dispersion relation can change from strongly dependent to quasi-independent behavior as a function of the applied field direction. This effect is explained in terms of the dipolar coupling between wires and its competition with the wire shape anisotropy. (C) 2002 Published by Elsevier Science B.V.