Micromagnetic simulations of spinel ferrite particles

This paper presents the results of simulations of the magnetization field ac response (at 2–12 GHz) of various submicron ferrite particles (cylindrical dots). The ferrites in the present simulations have the spinel structure, expressed here by M1−nZnnFe2O4 (where M stands for a divalent metal), and the parameters chosen were the following: (a) for n=0: M={Fe, Mn, Co, Ni, Mg, Cu }; (b) for n=0.1: M = {Fe, Mg} (mixed ferrites). These runs represent full 3D micromagnetic (one-particle) ferrite simulations. We find evidences of confined spin waves in all simulations, as well as a complex behavior nearby the main resonance peak in the case of the M = {Mg, Cu} ferrites. A comparison of the n=0 and n=0.1 cases for fixed M reveals a significant change in the spectra in M = Mg ferrites, but only a minor change in the M=Fe case. An additional larger scale simulation of a 3 by 3 particle array was performed using similar conditions of the Fe3O4 (magnetite; n=0, M = Fe) one-particle simulation. We find that the main resonance peak of the Fe3O4 one-particle simulation is disfigured in the corresponding 3 by 3 particle simulation, indicating the extent to which dipolar interactions are able to affect the main resonance peak in that magnetic compound.