Transport properties of transition-metal-encapsulated Si cages

We performed density functional pseudopotential calculations of the spin-dependent transport through transition-metal-atom-encapsulated Si cages Si12X (X=Mn, Fe, and Co). The effect of the metal atom on conductance is studied. Mn- and Fe-doped systems show highly spin-polarized transmission whereas the magnetization in Co-doped system is quenched. It is found that electrons are transferred from Si atoms into the minority d orbitals of the metal atoms. The conductance decreases as these electrons become localized around the encapsulated atoms.