Dependence on the temperature of magnetic anisotropies in Fe-based alloys of Finemet

This paper deals with magnetic anisotropies in Fe-based nanostructured materials. Alloys of Finemet are studied which were obtained from amorphous ribbons by zero-field annealing and by annealing in longitudinal or transverse magnetic fields. A comparison is made between the anisotropies induced during the production processes and those induced by applying external stresses. The analysis is carried out, at temperatures in the range 20-300 K, through the behavior of the initial magnetic permeability and the saturation magnetization intensity. The anisotropy constant values show an increase with decreasing temperature that can be well described by an exponential dependence and are always one or two orders of magnitude lower than the local magnetocrystalline anisotropy. The results are considered on the basis of the random anisotropy model generalized to two magnetic phase systems.