Stable T2Si(n) (T = Fe, Co, Ni, 1 < or = n < or = 8) cluster motifs

First principles studies on the geometry, electronic structure, and magnetic properties of neutral and anionic Fe(2)Si(n), Co(2)Si(n), and Ni(2)Si(n) (1 < or = n < or = 8) clusters have been carried out within a gradient corrected density functional framework. It is shown that these clusters display a variety of magnetic species with varying magnetic moment and different magnetic coupling between the two transition metal atoms. While Fe(2)Si(n) clusters are mostly ferromagnetic with large moments, Ni(2)Si(n) clusters are mostly nonmagnetic. Our studies of the variation of 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 that many of the motifs are quite stable and could be suitable as building blocks for generating magnetic cluster assembled materials. The studies also reveal motifs that could be used in molecular electronic devices to generate spin polarized currents or large magnetoresistance.