Tunnel barrier to spin filter: Electronic-transport characteristics of transition metal atom encapsulated in a small Cadmium Telluride cage

First-principles theory-based comparative electronic-transport studies were performed for an atomic chain of Au, a bare Cd₉Te₉ cage-like cluster, and a single transition metal (TM) (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd) atom encapsulated within the Cd₉Te₉ using Au(111) as the electrodes. The bare cluster was semiconducting and acted as a tunnel barrier up to a particular applied bias and then beyond that the device displayed a linear current-voltage relationship. Several TMs (Ti, V, Cr, Mn, Fe) encapsulated in the cage showed a half-metallic behavior and spin-filtering effect in the I-V characteristics of the device. Detailed qualitative and quantitative analyses of the I-V characteristics for metallic, semiconducting, and half-metallic nanostructures were carried out for quantifying the use of these TMs in spintronic device applications.