Very Low Field ac-Response at the Loss of Long Range Magnetic Order in Amorphous Fe<inf>90</inf>Zr<inf>10</inf>

Low temperature ac-susceptbility measurements over 5 decades of ac-field (0.08 - 8000 A/m) have been carried out on amorphous ribbons of Fe90Zr10 and Fe91Zr9. We find that at very low fields (0.8 to 24 A/m) ac-response measurements eliminate the influence of domain and domain wall motion, the well known Hopkinson peak effects, to reveal clearly the reentrant characteristics. With such studies a reentrant freezing temperature Tsfis unambiguously revealed with an evident knee in χ″(T) and a corresponding well defined peak in χ″(T). The latter is found to be independent of the applied field (0.8 to 8 A/m) while being weakly dependent on the frequency (10-1000 Hz). We thus find Tsfto be 25 K and 40 K respectively for Fe90Zr10 and Fe91Zr9, amorphous ribbons. © 1993 IEEE