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 Si ₁₆H ₁₆ endohedral cage generally too small to encapsulate 3d metal dopant atoms. For the next larger fullerene-like cage, however, we identify perfectly symmetric M@Si ₂₀H ₂₀ (M=Co, Ti, V, and 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.