Magnetization Process in Thin Laminations up to 1 GHz

Modeling High-Frequency Magnetic Losses in Transverse Anisotropy Amorphous Ribbons

“…The numerical analysis of (5) shows that the magnetostatic field H ms , calculated for the range of experimental domain widths 100 μm ≤ w d ≤ 500 μm [4] tends to asymptotically saturate with the increase of the number N of domains. Fig.…”

“…Kerr measurements show that some dw activity actually takes place. It has, for magnetostatic reasons, a rearrangement character, providing no net contribution to the magnetization, and becomes fully damped in the megahertz range [4]. It is then concluded that on entering the radiofrequency regime, where only rotations survive, the material emulates the ideal classical limit of a structureless material with fully homogeneous magnetization process [5].…”

“…T RANSVERSE field-annealed amorphous and nanocrystalline tapes display excellent broadband magnetic properties, showing, in particular, higher permeability and lower energy losses than soft ferrites at all frequencies, up to the gigahertz range [1]- [4]. This occurs in spite of their metallic character and the ensuing energy dissipation by eddy-current losses.…”

Recent Developments in Magnetic Measurements: from Technical Method to Physical Knowledge

“…By creating, in particular, an anisotropy axis perpendicular to the ribbon length (i.e. to the applied field), we can obtain, especially in Co-based alloys, a combination of high permeability and low losses far superior to the one exhibited by the conventional Mn-Zn and Ni-Zn ferrites in a range of frequencies spanning from DC to 1 GHz [5,34]. The key to this remarkable behavior is assumed to lie, besides the low value of the macroscopic magnetic anisotropy, in the progressive relaxation of the domain wall displacements with increasing frequency, their role being taken up by rotational processes.…”

“…Recently introduced ultrafast magneto-optical techniques [3] permit one to directly observe the time dependent magnetization process down to picosecond resolution [4]. Early damping of domain wall relaxation with increasing frequency is observed in thin metallic plates if rotations can simultaneously occur [5]. For magnetic compounds with Curie temperature close to room temperature, appreciable entropy variation can be obtained under a changing magnetic field.…”