COMPOSITIONAL DEPENDENCE OF THE STRESS PLUS FIELD-INDUCED ANISOTROPY IN CO-NI-SI-B AND CO-FE-NI-SI-B AMORPHOUS ALLOY RIBBONS

Compositional dependence of the stress plus field induced magnetic anisotropy and the compositional dependence of the index, n, of proportionality between the induced magnetic anisotropy and the saturation magnetization in (Co(1-x)Ni(x))75Si15B10 (x = 0, 0.08, 0.15 and 0.22) and [Co1-x(Fe0.5Ni0.5)x]75Si15B10 (x = 0.20, 0.50 and 0.80) have been measured. To explain the microscopic origin of this anisotropy several contributions have been proposed, namely: (1) atomic pair ordering and, (2) tetrahedral holes surrounded by 3Co-1Fe and 1Co-3Fe, while the contributions of tetrahedral holes such as 3Co-1Ni and 1Co-3Ni seem to be negligible. The compositional variation of the index, n, for Co-Ni-Si-B system is similar to that obtained for the induced anisotropy and could be satisfactorily interpreted if it is assumed the non-magnetic character of Ni atoms which dilutes the interactions of Co atoms as the Ni content increases. Moreover, the variation of index, n, for Co-Fe-Ni-Si-B system is found to be similar in overall compositional range and it shows different behavior to that of the induced anisotropy. The influence of pre-annealing on this anisotropy when the magnetic field is applied either longitudinally or transversely to the ribbon axis for the composition (Co0.50Fe0.25Ni0.25)75Si15B10 has been also measured.