Electronic structure and electron energy-loss spectra of Sr0.35CoO2

Abstract: The electronic structure of Sr0.35CoO2, structurally analogous to the layered Na x CoO2, has been evaluated using the local spin density approximation (LSDA). We find that evident c-dispersions appear in both the and a 1g Co-derived bands, demonstrating the existence of a notable interplanar interaction in Sr0.35CoO2. The LSDA+U calculation reveals that the electronic structure, in particular the band splitting between the spin-up and spin-down electrons, changes evidently along with the increase of the effective on-site Coulomb interaction U. Analysis of theoretical and experimental electron energy-loss spectra (EELS) for the oxygen K-edge and the Co L23-edge suggests that the on-site interaction (U) in Sr0.35CoO2 is less than 3eV which is noticeably weaker than the estimated value (from 5 to 8eV) in the Na x CoO2 materials. [Copyright &y& Elsevier]