Anomalous AC Magnetization in Liquid Quenched Amorphous Alloys (lqa's) of Iron-Zirconium and Cobalt-Zirconium

AC susceptibility measurements have been carried out on transition metal based liquid quenched amorphous alloys (LQA's) of FeZr and CoZr in the temperature range 77 - 300 K. A saturation in the susceptibility is observed at a temperature T₁, which is found to be dependent upon the Fe (or Co) content of the sample. The samples with low concentrations of the magnetic impurity show a further increase in the ac susceptibility at a lower temperature T₂ beyond the saturation region. This feature is absent in the Fe rich sample. Our results have been explained in terms of a ferromagnetic to spin-glass transition.