Anisotropy Field in Ni Nanostripe Arrays

Anisotropy fields of nanostripe arrays can be investigated by various techniques. One of these techniques is the ferromagnetic resonance spectroscopy due to the fact that the resonance field depends directly on the anisotropy field strength and its angular spread. In order to understand the dynamic fenomena in these samples, nanostripe arrays of Ni have been prepared by interference lithography. The film thickness is 45 nm for a lattice period of 2.7 μm and the stripe width equals 1500 and 750 nm. Ferromagnetic resonance measurements have been carried out at a frequency of 9.75 GHz as a funcion of H. The resonance field of the absorption peak increases upon changing the angle from parallel (0^°) to perpendicular (90^° ) to the film plane. This behaviour can be explained by the relation between resonance field, frequency and anisotropy field determined by demagnetizing factors and magnetization angle with respect to the sample easy axis direction after energy minimization.