MAGNETIC AND TRANSPORT-PROPERTIES OF FE-ZR-B-(CU) AMORPHOUS-ALLOYS

FeZrB metallic glasses present magnetic properties that are enhanced c ompared to the pure FeZr ones. In particular, a large increase of the Curie temperature has been found. Magnetic and Mossbauer measurements show a decrease of the spin-glass character and a parallel homogenizat ion of the hyperfine-field distribution as the boron concentration inc reases. Resistivity versus temperature measurements show a change in b ehaviour with B content: in the samples with small amounts of boron, a minimum in the resistivity versus temperature curves appears near the Curie temperature, while samples with high boron content show a low-t emperature minimum, characteristic of most metallic glasses. The analy sis of the results suggests that the evolution of the magnetic behavio ur is related to changes in the density of states at the Fermi level, rather than to changes in the Fe-Fe distances. This is in agreement wi th published data on the specific heat of FeZr and FeB glasses. The in fluence of boron is shown to greatly enhance the weak itinerant ferrom agnetism of FeZr glasses, leading to stronger ferromagnetic behaviour. The characteristic features of the resistivity are analysed in terms of localization effects on the conduction electrons, which extend to h igher temperatures in the low-boron-content alloys.