Field and temperature dependence of magnetization in FeCu-based amorphous alloys

In this paper, the production of FeCu-based FeCuZr amorphous alloys by bah milling is reported. The thermal dependence of magnetization for the (Fe0.5 Cu0.5)(85)Zr-15 (at. %) amorphous alloy has been found to show a dramatic f ield dependence of the kink point of the magnetization. This kink correspon ds to a temperature different from the Curie temperature, above 400 K, of t he ferromagnetic phase, which, according to spin waves fitting, can be indu ced by applying external fields. Just above 235 K, the thermoremanence incr eases sharply, and this feature strongly suggests an increase of the ferrom agnetic ordering under zero field heating. Neutron diffraction experiments seem to confirm the enhancement of spin alignment. The thermal expansion ab ove the compensation temperature is proposed to be the origin of the thermo remanence enhancement through the anti-Invar effect as might be explained w ithin the framework of recent ab initio calculations [M. van Schilfgaarde e t al., Nature (London) 400, 46 (1999)].