Stability and magnetic properties of T2Sin (T = Cr, Mn, 1 ≤ n ≤ 8) clusters

First-principles studies on the geometry, electronic structure, and magnetic properties of neutral and anionic Cr2Sin and Mn2Sin (1 <= n <= 8) have been carried out within a gradient corrected density-functional framework. We find that Cr2Sin clusters containing up to five Si atoms and Mn2Sin clusters containing up to eight Si atoms are all marked by finite local spin moments at the transition-metal site that order ferromagnetically or antiferromagnetically depending on the size and the charged state. Our studies of the variation in the binding energy upon addition of successive Si atoms and the gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital indicate Mn2Si4 to be a potential motif for generating magnetic cluster-assembled material. While the individual Mn2Si4 motif has a ground state with antiferromagnetically coupled local moments, the studies on the assembly of two basic motifs show that it favors a ferromagnetic state. It is hoped that the present work will motivate examination of such assemblies in the recently developed cluster beam deposition experiments.