Orientador: Gaston Eduardo Barberis

Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin

Resumo: Não informado

Abstract: Room-temperature X- and Q- band ESR spectra of the high-Tc superconductor Yba2Cu3O7-x and the semiconductors Y2baCuO5 and BaCuO2+x are studied experimentally and theoretically by measuring, calculating, and fitting the powder spectra corresponding to an anisotropic Zeeman Hamiltonian for...

Abstract: Room-temperature X- and Q- band ESR spectra of the high-Tc superconductor Yba2Cu3O7-x and the semiconductors Y2baCuO5 and BaCuO2+x are studied experimentally and theoretically by measuring, calculating, and fitting the powder spectra corresponding to an anisotropic Zeeman Hamiltonian for CU2+ in orthorhombic and tetragonal local symmetries ESR and x-ray studies in their corresponding oxygen-deficient stoichiometries, obtained by heat treatment under vacuum, were also done. Our results support those of Bowdeen et al. and Vier et al. in Rba2Cu3O7-x (R = Y, Eu), indicating that the Cu(1) and Cu(2) atoms in the pure Yba2Cu3O7-x phase are not ESR active and the small resonance observed in these compounds comes from other residual phases. The purest Yba2Cu3O7-x samples that we were able to prepare still have 0.1-0.5% mass fraction of other residual copper compounds which are responsible for the observed resonance