Micromagnetic simulations of spinel ferrite particles

摘要

This paper presents the results of simulations of the magnetization field{\it ac} response (at $2$ to $12$ GHz) of various submicron ferrite particles(cylindrical dots). The ferrites in the present simulations have the spinelstructure, expressed here by M$_{1-n}$Zn$_{n}$Fe$_2$O$_4$ (where M stands for adivalent 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 \} (mixedferrites). These runs represent full 3D micromagnetic (one-particle) ferritesimulations. We find evidences of confined spin waves in all simulations, aswell 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 fixedM reveals a significant change in the spectra in M = Mg ferrites, but only aminor 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 Fe$_3$O$_4$(magnetite; $n=0$, M = Fe) one-particle simulation. We find that the mainresonance peak of the Fe$_3$O$_4$ one-particle simulation is disfigured in thecorresponding 3 by 3 particle simulation, indicating the extent to whichdipolar interactions are able to affect the main resonance peak in thatmagnetic compound.