In the search for new materials for desired applications, alloying offers a promising way of combining metals to obtain a new material with properties that are different from those of the constituent elements. However, not all combinations of metals are miscible. One way to coax immiscible metals to form an alloy is to deposit them as a thin layer on a substrate. We have performed combinatorial ab initio calculations to study the factors that govern this process, and identified suitable candidates that may behave in the desired way. One of the candidates identified by us, Fe-Au/Ru(0001), has been shown by our experimental collaborators, in the group of Sylvie Rousset at the Universite de Paris – Denis Diderot, to form a stable long-range-ordered surface alloy, even though Fe and Au are bulk-immiscible. Surprisingly, our investigations show that it is magnetic interactions and not stress-relief, that provide the main driving force for mixing in this system.
Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India