Reversible and irreversible components of tensor magnetization and magnetostriction

Tensor magnetostriction and magnetization hysteresis loops for a 25 mm ferrite magnet cube were measured. These describe the magnetization properties and reflect the anisotropy of the system. The sample investigated allowed the magnetization to be interpreted in terms of a magnetization vector rotation process and described by the Stoner–Wohlfarth model. The reversible and irreversible components were extracted for both the magnetostriction and magnetization tensors. Up to now, very few direct measurements of these reversible changes in strain have been reported. The different magnitudes of reversible magnetization and magnetostriction are analyzed and explained qualitatively by a representation involving both magnetization and magnetostriction processes. The magnetostrictive effect is taken into account quite simply by considering a demagnetized sphere distorted into an ellipsoid of revolution when saturated. The ellipsoid will rotate as the magnetization vector according to the Stoner–Wohlfarth model. Two cases are illustrated depending on the easy axes location. These explain the experimental results obtained with the ferrite sample.