Evaluation of endohedral doping of hydrogenated Si fullerenes as a route to magnetic Si building blocks

Density-functional theory based global geometry optimization is used to scrutinize the possibility of endohedral doping of hydrogenated Si fullerenes as a route to Si nanostructures with high magnetic moments. In contrast to previous suggestions, our unbiased sampling finds the smallest Si16H16 endohedral cage generally too small to encapsulate 3d metal dopant atoms. For the next larger fullerene-like cage though, we identify perfectly symmetric MSi20H20 (M = Co, Ti, V, Cr) cage structures as ground states. These structures conserve the high spin moment of the dopant atom and therewith underscore the potential of this Si nanoform for novel cluster-based materials with unique magnetic properties.