Finite size effects in the static and dynamic magnetic properties of FeNi wire array structures

We report on systematic studies of both the static and dynamic properties of FeNi wire arrays on GaAs(001) substrates. The wires were between 0.4 and 10 μm wide and were separated by twice their width. The static magnetic properties were investigated using magneto optical Kerr effect magnetometry. The dynamical magnetic properties (spin-waves) were investigated by Brillouin light scattering in the Voigt geometry. With an external field applied along the hard shape axis, the saturation field was observed to increase and the spin-wave energies decreased with decreasing wire size. For fields applied along the (easy) axis of the wire, we observed an increase in the coercive field as the width of the wire is decreased. The frequency of the surface mode was found to increase with decreasing wire size while the first volume mode frequency was found to be wire size independent.