First-principles study of structural, magnetic and electronic properties of small FeRh alloy clusters

The structural, electronic and magnetic properties of small ${\rm Fe}_m {\rm Rh}_n$ clusters having $N = m+n \leq 8$ atoms are studied in the framework of a generalized-gradient approximation to density-functional theory. For $N = m+n \leq 6$ a thorough sampling of all cluster topologies has been performed, while for $N = 7$ and 8 only a few representative topologies are considered. In all cases the entire concentration range is systematically investigated. All the clusters show ferromagnetic-like order in the optimized structures. As a result, the average magnetic moment per atom $\bar\mu_N$ increases monotonously, which is almost linear over a wide range of concentration with Fe content. A remarkable enhancement of the local Fe moments beyond 3 $\mu_B$ is observed as result of Rh doping. The composition dependence of the binding energy, average magnetic moment and electronic structure are discussed.