Self-organized nanowires: Evidence of dipolar interactions from ferromagnetic resonance measurements

We present ferromagnetic resonance (FMR) results on dense hexagonal arrays of Ni nanowires (NW) performed at 34GHz. The measurements show that the angular variation of the resonance field follows an uniaxial anisotropy law, as expected from the shape of the individual wires. However, the magnitude of the effective anisotropy clearly indicates that the effect of dipolar interaction between the wires amounts to a decrease of nearly 20% of the single-wire anisotropy, 2πMs. Also, the angular variation of the FMR linewidth indicates that the NW are very well aligned and reflects anisotropy variations which correlate with the array long-range order. © 2004 Elsevier B.V. All rights reserved.