Participation of carbon in the electronic structure of YBa2Cu3O7- delta.

Abstract

Electron-energy-loss measurements in 2-nm-sized regions of single-crystal YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} show about 0.5 wt. % carbon dissolved in the matrix. The energy-loss near-edge fine structure (ELNES) at the carbon 1{ital s} absorption edge favors an environment similar to BaCO{sub 3}. The carbon ELNES is correlated with the oxygen 1{ital s} ELNES in a way that suggests that carbon-derived orbitals participate in the electronic structure within 1 eV of the Fermi level.