Structure Dependent Magnetic Coupling in Cobalt-Doped Silicon Clusters

The structure of cobalt-doped silicon clusters, SinCo+ (n = 5-8) and SinCo2+ (n = 8-12), is investigated in a combined infrared multiple photon dissociation spectroscopy and density functional theory study. The singly doped clusters have exohedral structures in which the Co atom substitutes an atom of bare Si-n+1(+) dusters. In the doubly doped SinCo2+ clusters, the second Co atom is adsorbed to the singly doped counterparts and, for n >= 9, one of the Co atoms is encapsulated by a silicon cage. Computational analysis of the electronic and magnetic properties of the identified isomers indicates a distance dependent magnetic coupling between the Co atoms in the SinCo2+ dusters.