Influence of the short-range order on the magnetic properties of metallic glasses

The short-range order of metallic glasses has been investigated by x-ray absorption spectroscopy in order to explore the relation between the local structure and the magnetic properties. The structural information has been further contrasted with the results obtained from the use of other local probes such as Mössbauer spectroscopy. The existence of chemical preferences leading the metalloids, B and Si, to locate near one particular metallic species, Fe and Co respectively, is in the origin of the strong increase of the short-range order in the Co rich side, characterized by the appearance of a BCC-like structure around Fe for . Such an effect causes a decrease of the root mean square deviation of distance between Fe and its near-neighbour metallic atoms in the Co rich side , which is strongly correlated with the decrease of standard deviation of the distribution of hyperfine fields. The nearest-neighbour distances Fe-M and Co-M (M = Fe, Co) decrease for , and the Co-M one shows a minimum at y = 0.06. This behaviour has been used to explain some features of the dependence on the composition of the Curie temperature and the spin wave stiffness constant as well as the isomer shift of the alloys.