Distribution of the magnetic anisotropy in amorphous alloys ribbons

The magnetization curve of an amorphous ribbon along its axis has been calculated in the case of a variation in the intensity of the magnetic anisotropy, which is assumed to have an easy axis perpendicular to the ribbon axis. An expression is given for deriving the anisotropy distribution from the magnetization curve. The influence of small departures of the anisotropy axis from the perpendicular direction is studied. Measurements in as-cast ribbons of Co-rich alloys show that the anisotropy distribution is close to a Gaussian centered near the origin, i.e. almost no macroscopic anisotropy is present. These results are in agreement with the hypothesis made in previous studies to explain the evolution of the magnetization curve of some amorphous alloys with applied stress. The effect of preannealing on the anisotropy distribution induced by a transverse field and by stress annealing is shown to be a smoothing of the internal stresses.>