Magnetoelastic coupling constant of amorphous ferromagnetic alloys-A critical study

The determination of the magnetoelastic properties in Fe-rich amorphous alloys by using resonance methods is strongly affected by the kind of measurement done. In this work, we compare results obtained when using the vibrating reed method and the magnetically excited resonance one. Measurements have been performed on Fe₆₆Co₁₈Si₁B₁₅ amorphous ribbons with the induced anisotropy easy axis at 60 degrees with respect to the ribbon axis. The observed differences are large in all the measured range, and especially striking in the E(H=O)/E_s initial to saturation Young´s modulus ratio. After a detailed analysis of the expressions used to derive magnetoelastic quantities from the resonant frequencies values, these discrepancies are explained by the fact that the two methods measure different quantities: dependence of the Young´s modulus on the applied field (or ΔE effect) and magnetoelastic coupling coefficient, respectively