Magnetic and Mössbauer Study of Sputtered Amorphous Alloys Hf1-xTaxFe2

We have measured the magnetization and Mossbauer effect on vapor-quenched amorphous Hf 1- x Ta x Fe 2 alloys prepared by sputtering for x =0, 0.3, 0.5, 0.7, 0.9 and 1 from 4.2 to 300 K. We observed the spontaneous magnetization for all the present samples except for x =1, where the ferromagnetic moment and Curie temperature monotonically decrease with increasing Ta concentration. A comparison between the ferromagnetic and paramagnetic moments suggests that the alloys are an itinerant-electron ferromagnet. The reduced low-temperature magnetization falls characteristically below that of crystalline HfFe 2 and follows a T 3/2 law. From the broad Mossbauer spectrum below the Curie temperature we estimate the average hyperfine field. Ta-concentration and temperature dependence of the average hyperfine field agrees with that of the magnetization.