Affiliation: | Departamento de Fisica de la Materia Condensada C-XII, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain Departamento de Fisica, Comision Nacional de Energia Atomica, Av. del Libertador 8250, 1429, Buenos Aires, Argentina |
Abstract: | An alloy model is proposed for the electronic structure of high-temperature superconductors. It is based on the assumption that holes and extra electrons are localized in small copper-oxygen clusters, that would be the components of such an alloy. This model, when used together with quantum chemical calculations on small clusters, can explain the structure observed in the experimental densities of states of both hole and electron superconductors close to the Fermi energy. The main point is the strong dependence of the energy level distribution and composition on the number of electrons in a cluster. The alloy model also suggests a way to correlate Tc with the number of holes, or extra electrons, and the number of adequate clusters to locate them. |