Ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies

摘要

We develop a model for ferromagnetic resonance in systems with competinguniaxial and cubic anisotropies. This model applies to (i) magnetic materialswith both uniaxial and cubic anisotropies, and (ii) magnetic nanoparticles witheffective core and surface anisotropies; We numerically compute the resonancefrequency as a function of the field and the resonance field as a function ofthe direction of the applied field for an arbitrary ratio of cubic-to-uniaxialanisotropy. We also provide some approximate analytical expressions in the caseof weak cubic anisotropy. We propose a method that uses these expressions forestimating the uniaxial and cubic anisotropy constants, and for determining therelative orientation of the cubic anisotropy axes with respect to the crystalprinciple axes. This method is applicable to the analysis of experimental dataof resonance type measurements for which we give a worked example of an ironthin film with mixed anisotropy.