Measurements and Modelling of Amorphous and Nanocrystalline Materials up to 1 GHz

We highlight the challenges posed by the experimental and theoretical assessment of the magnetic losses in magnetic materials for high-frequency applications, with specific reference to amorphous and nano-crystalline magnetic materials. After pointing out the role of magnetic materials in high-frequency applications and problems raised by broadband magnetic characterization, we discuss the physical modeling of magnetic permeability and losses over the whole extended range of frequencies where the magnetic response of the material can be appreciated. The experiments have been performed on field annealed Co-based and nanocrystalline Finemet type ribbons, having thickness ranging between ~13 µm and ~25 µm. The samples under test are endowed with defined transverse magnetic anisotropy. Magnetic losses and complex permeability have been measured from DC to 1 GHz by combined application of fluxmetric and transmission line methods. The remarkable wideband soft magnetic properties of these materials are theoretically assessed by combined solution of Maxwell’s and Landau-Lifshitz-Gilbert equations and its consistent incorporation with the concept of loss decomposition