SPIN FLUCTUATION IN AMORPHOUS Y-NI ALLOYS

The effects of thermal spin fluctuation on the magnetic properties and its concentration dependence are investigated for ferromagnetic amorp hous Y-Ni alloys. The T4/3 dependence of the square of the magnetizati on M2 is observed in amorphous Y12Ni88 and Y14Ni86 alloys. The validit y of this relation becomes poor as the Ni concentration increases. Spo ntaneous volume magnetostriction omega(s) is observed in these alloys. The value of omega(s) becomes larger with increasing Ni concentration , indicating an increase in the spin fluctuation. The amplitude of the local spin-density fluctuation for amorphous Y10Ni90 alloy saturates after a linear increase above the Curie temperature T(C). The inverse magnetic susceptibility for amorphous Y10Ni90 alloy follows the Curie- Weiss law above T(C) and shows a change in the slope at the temperatur e corresponding to the saturation of the amplitude.