Ferromagnetic resonance in periodic particle arrays

We report on the measurements of the ferromagnetic resonance spectra of arrays of submicron size periodic particle arrays of permalloy produced by electron-beam lithography. In contrast to plane ferromagnetic films, the spectra of the arrays show a number of additional resonance peaks, whose position depends strongly on the orientation of the external magnetic field and the interparticle interaction. Time-dependent micromagnetic simulations of the ac response show that these peaks are associated with coupled exchange and dipolar spin-wave modes.