Electronic structure of the superconducting layered perovskite niobate

The electronic energy-band structure for RbLaNb₂O₇, which is closely related to the layered perovskite niobate superconducting KCa₂Nb₃O₁₀ and metallic KLaNb₂O₇ with Li intercalation, has been calculated by using the scalar-relativistic full-potential linearized augmented-plane-wave method within the local-density approximation. The result of the calculation shows that this compound is a band insulator with a small gap, and its conduction band is a typical two-dimensional one and the valence band is rather three dimensional. We can conclude that the layered perovskite niobate KCa₂Nb₃O₁₀ is a band insulator that can be superconducting with electron doping, and have the highly two-dimensional electronic structure.