The band electronic structure of the high-temperature superconducting ceramics La2-xMxCuO4and YBa2Cu3O7-y

Abstract

Atomic-orbital-based calculations have been carried out for the one-electron band structures and densities of states in the tetragonal and orthorhombic phases of stoichiometric La₂CuO₄, in orthorhombic YBa₂Cu₃O₇, and in tetragonal YBa₂Cu₃O₆. Close similarities in the copper environments lead to very similar one-electron energy-band shapes near the Fermi level. In all four phases the density of states at the Fermi level is low, between 1.1 and 1.6 states/eV/Cu atom, and the bands crossing E_F are quasi-two-dimensional or quasi-one-dimensional.