ELECTRONIC-STRUCTURE OF LABA2CU2NBO8 AND RELATED CANDIDATES FOR HIGH-TC SUPERCONDUCTIVITY

The nominally tetragonal, triple-perovskite compound LaBa2Cu2NbO8 contains a pair of CuO2 layers that are separated by an oxygen-free La layer as well as a BaO-NbO2-BaO triple layer. The results of linear augmented-plane-wave band calculations for this (and a proposed isoelectronic Ti) compound exhibit electronic features near E(F) (i.e., a pair of nearly degenerate, half-filled Cudx2-y2-Opx,y sigma-antibonding subbands) that are characteristic of known cuprate superconductor parent compounds. This suggests that high-T(c) superconductivity may be possible in appropriately doped LaBa2Cu2NbO8-, LaBa2Cu2TaO8-, or BaLa2Cu2TiO8-type samples (or their chemical equivalents), although initial efforts have been unsuccessful thus far in the case of the group-V-type materials.