Half-metallicity in smallest cage-like cluster of CdTe with doping of transition metal atoms

We report first principles theory based electronic structure studies of a semiconducting stoichiometric cage-like Cd9Te9 cluster. Substantial changes are observed in the electronic structure of the cluster on passivation with fictitious hydrogen atoms, in particular, widening of the energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital and enhancement in stability of cluster is seen. The cluster, when substitutionally mono-doped for a Cd by a set of 3d and 4d transition metal atoms (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh and Pd), is found to acquire polarization as seen from spin resolved density of states near Fermi level. Further, such mono-doping in passivated cluster shows half-metallic behavior. Mapping of partial density of states of each system on that of undoped cluster reveals additional levels caused by doping each TM atom separately. In the 3d elemental doping, Ti and Mn doping result into electron type doping whereas all other cases result into hole doped systems. For all the 4d elements studied, it is akin to the doping with holes for Cd substitution in the outer ring, whereas for Ru and Rh, there is electron type doping in case of substitution for Cd in central ring upon passivation. A comparison of partial density of states plots for bare and passivated clusters, on doping with transition metal atoms, suggests suitability of the cage-like cluster for spintronics applications.

Automated summary

This study presents electronic structure studies of a semiconducting stoichiometric cage-like Cd9Te9 cluster based on first principles theory. Passivation of the cluster with fictitious hydrogen atoms leads to substantial changes in its electronic structure, including widening of the energy gap and increased stability. Mono-doping of the cluster with transition metal atoms shows polarization near the Fermi level, and the passivated cluster exhibits half-metallic behavior. Comparisons between the partial density of states of bare and passivated clusters upon doping suggest potential suitability of the cage-like cluster for spintronics applications.