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

摘要

The electronic structure of Sr0.35CoO2, structurally analogous to the layeredNaxCoO2, has been evaluated using the local spin density approximation (LSDA).We find that evident c-dispersions appear in both the e'g and a1g Co-derivedbands, demonstrating the existence of a notable interplanar interaction inSr0.35CoO2. The LSDA+U calculation reveals that the electronic structure, inparticular the band splitting between the spin-up and spin-down electrons,changes evidently along with the increase of the effective on-site Coulombinteraction U. Analysis of theoretical and experimental electron energy-lossspectra (EELS) for the oxygen K-edge and the Co L23-edge suggests that theon-site interaction (U) in Sr0.35CoO2 is less than 3eV which is noticeablyweaker than the estimated value (from 5eV to 8eV) in the NaxCoO2 materials.