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International audience; —The concept of loss separation based on the Statistical Theory of Losses (STL) provides complete and accurate description of the frequency dependence of the energy losses in non-oriented soft magnetic sheets under the assumption of uniform magnetization reversal through the sheet cross-section. This assumption, implying a simple standard formulation for the classical loss component, has been recently challenged in the literature, in favor of a non-uniform reversal mechanism, expected to prevail in highly non-linear materials, where saturation magnetization wavefronts are deemed to symmetrically propagate across the sheet thickness (Saturation Wave Model, SWM). Different conclusions regarding the dynamic loss analysis and its decomposition into the classical and excess loss components correspondingly emerge. In this paper we discuss detailed investigations on the broadband energy loss versus frequency behavior in different non-oriented Fe-Si and low-carbon steel sheets. The experiments can be fully and consistently described by the STL. This occurs, in particular, for high-induction values and near-squared hysteresis loops, a predictable condition for adopting the SWM, which fails instead to account for the experiments.

The magnetic energy losses and their frequency dependence in Mn-Zn ferrites have been investigated in theory and experiment. A novel theoretical approach has been developed, which is based on the concept of loss decomposition and the appraisal of the separate contributions provided by domain wall displacements and moment rotations. It is shown that the role of eddy currents in energy dissipation is a minor one and can be appreciated in the megahertz region only. The loss contribution by domain walls versus frequency is obtained from knowledge of the quasistatic energy loss, whereas the rotational real and imaginary permeabilities are derived as solutions of the Landau-Lifshitz-Gilbert equation for distributed values of the effective anisotropy field. The model successfully applies to results obtained on commercial ferrite ring samples