Ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies
Groupe d'Étude de la Matière Condensée, Université de Versailles St. Quentin, CNRS UMR8635, 45 Av. des États-Unis, 78035 Versailles, France
2 Depto. de Fisica and IFIMUP, Universidade do Porto, Rua Campo Alegre 687, 4169 007 Porto, Portugal
Revised: 2 March 2007
Published online: 4 April 2007
We develop a model for ferromagnetic resonance in systems with competing uniaxial and cubic anisotropies. This model applies to (i) magnetic materials with both uniaxial and cubic anisotropies, and (ii) magnetic nanoparticles with effective core and surface anisotropies; We numerically compute the resonance frequency as a function of the field and the resonance field as a function of the direction of the applied field for an arbitrary ratio of cubic-to-uniaxial anisotropy. We also provide some approximate analytical expressions in the case of weak cubic anisotropy. We propose a method that uses these expressions for estimating the uniaxial and cubic anisotropy constants, and for determining the relative orientation of the cubic anisotropy axes with respect to the crystal principle axes. This method is applicable to the analysis of experimental data of resonance type measurements for which we give a worked example of an iron thin film with mixed anisotropy.
PACS: 76.50.+g – Ferromagnetic, antiferromagnetic, and ferrimagnetic resonances / 75.75.+a – Magnetic properties of nanostructures / 75.10.Hk – Classical spin models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007