Magnetic properties of amorphous YFe2 obtained by milling

Fe-57 Mossbauer spectroscopy in zero and non-zero applied magnetic fields, a.c. magnetic susceptibility and d.c. magnetization measurements have been performed on amorphous YFe2 (a-YFe2) milled powders obtained from the intermetallic compound in the temperature range from 4.2 to 300 K. The Mossbauer spectra recorded under an external magnetic field indicate that a-YFe2 powder does not display a pure ferromagnetic interaction and shows remanence effects at low temperatures. The peak of the a.c. magnetic susceptibility, which occurs at T(f)approximate to 70 K, has a weak frequency dependence behavior, characteristic of a spin-glass phase transition-type. This behavior and the Mossbauer results lead us to conclude the absence of fine particle superparamagnetism effects and that the a-YFe2 obtained by milling presents a complex magnetic structure. These results are consistent with those reported for Y-Fe amorphous films of similar composition, which have been described as displaying asperomagnetic order. The 120 h milled powder shows the presence of segregated alpha-Fe clusters detected by Mossbauer spectroscopy. These clusters were no longer observed after the sample had been treated at 523 K for 6 h. (C) 1998 Elsevier Science S.A.