Determination of susceptibility and specific heat critical exponents for weak itinerant-electron ferromagnets from vibrating reed experiments

We report the observation of a linear relationship between the magnetic contribution to Young's modulus, DeltaE/E-0, and inverse magnetic susceptibility chi(-1) for amorphous weak itinerant-electron ferromagnets Fe90Zr10 and Fe91Zr9 in the asymptotic critical region near the ferromagnetic-paramagnetic phase transition. The proportionality DeltaE(T)/E(0)proportional tochi(-1)(T) is shown to provide as accurate a means of determining the asymptotic critical exponent gamma and the leading "correction-to-scaling" amplitudes for susceptibilty from the DeltaE/E-0 data as a direct measurement of magnetic susceptibilty does. Similarly, the well-known relation between the magnetic contributions to sound velocity and specific heat is fully exploited to extract accurate estimates for the universal critical amplitude ratio A(+)/A(-) and the asymptotic critical exponents alpha(+/-) for the specific heat from the sound velocity data. The presently determined values of alpha(+/-) and gamma, together with the reported value for spontaneous magnetization critical exponent beta, not only obey the scaling equalities alpha(+)=alpha(-) and alpha+2beta+gamma=2 but also assert that the atomic magnetic moments in the alloys in question interact with one another through an attractive interaction which decays faster than 1/r(5) with the interatomic spacing, r.