Oxygen-disorder effects on the electronic structure of YBa2Cu3O6+ delta.

Abstract

The electronic structure of ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6+\mathrm{\ensuremath{\delta}}}$ is calculated in the framework of the tight-binding Hamiltonian. The effects of the oxygen concentration \ensuremath{\delta} and its spatial ordering in the basal plane are studied by means of the Bethe-lattice method. The local density of states at the various Cu and O sites are calculated as a function of \ensuremath{\delta} and of the degree of oxygen ordering. Special attention is given to the number of holes h in both the ordered and disordered systems for various concentrations. We find that the electronic structure at the ${\mathrm{CuO}}_{2}$ planes is almost insensitive to the degree of order, in contrast to the local density of states of sites located in the basal plane.