Growth behavior and magnetic properties of SinFe (n=2-14) clusters

The growth behavior and magnetic properties of SinFe (n=2-14) clusters have been investigated using the density functional theory (DFT) within the generalized gradient approximation (GGA). Extensive search of the lowest-energy structures has been conducted by considering a number of structural isomers for each cluster size. In the ground state structures of SinFe clusters, the equilibrium site of Fe atom gradually moves from convex, to a surface, and to a concave site as the number of Si atoms increases from 2 to 14. Starting from n=10, the Fe atom completely falls into the center of the Si outer frame, forming metal-encapsulated Si cages. Maximum peaks were observed for SinFe clusters at n=5, 7, 10, 12 on the size-dependence of second-order energy difference, implying that these clusters possess relatively higher stability. The electronic structures and magnetic properties of SinFe clusters were discussed. We find that the magnetic moment of the Fe atom in SinFe clusters is quenched around the size of n=9-10, due to strong hybridization between the 4s and 3d states of Fe and the 3s and 3p states of Si.