Structural anisotropy of amorphous alloys with creep-induced magnetic anisotropy

Amorphous ribbons of different composition were annealed under tensile stress. This yielded a creep-induced magnetic anisotropy with an easy magnetic plane perpendicular to, or an easy axis parallel to, the ribbon direction, depending on the alloy composition. X-ray diffraction experiments and simple thermal expansion measurements show that the stress-annealed samples reveal a structural anisotropy which is released by post-annealing as a residual strain. This strain increases with the annealing stress and is therefore correlated with the induced magnetic anisotropy. The origin of this frozen-in strain is discussed in terms of structural heterogeneity in the strength of local atomic bonds. It is suggested that the induced magnetic anisotropy is related to the local magneto-elastic coupling in regions with strong bonding forces.