Low-power nonlinear effects in the ferromagnetic resonance of spheres of Ba3Zn2Fe24O41

Abstract

Foldover effects in the ferromagnetic resonance spectra of Ba₃Zn₂Fe₂₄O₄₁ (Zn₂Z) were observed at 35 GHz. The critical microwave field for the effect was about two orders of magnitude smaller than that calculated for models of foldover due to magnetocrystalline anisotropy. Since these particles were spherical within optical microscope resolution, it is not anticipated that shape anisotropy contributes to this nonlinear effect. Because of the large anisotropy field (481 mT) it is likely that higher‐order effects can also contribute to nonlinear behavior. This is the first reported example of foldover in a hexagonal ferrite.