A novel spin wave from low-dimensional superlattice of microstructured ferromagnetic thin films

We examined the dynamical magnetic properties of microstructured ferromagne tic thin films with low-dimensional superlattice structure by ferromagnetic resonance (FMR) spectroscopy. The superlattice is composed of one- or two- dimensional arrays of "islands" of permalloy on micron scale. The conventio nal standing spin wave (SSW) model couldn't reproduce the angular variation of the observed FMR spectra. We analyzed the observed FMR spectra by the d ipolar spin wave (dipolar SW) model describing collective motion of giganti c magnetic moments, which are defined by a whole magnetization of the semim acroscopic-scale "island". From the analysis of the observed angular variat ion, the dispersion relation for the dipolar SW was found to be the general formulation for the dynamical magnetic properties of the semimacroscopic s ystems. It was found from the analysis of the distance dependence of the in ter-island magnetic interactions that the size and the shape of the ferroma gnetic islands are not negligible in the dipolar SW.