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

TL;DR

This study investigates the electronic structure and electron energy-loss spectra of Sr0.35CoO2, revealing notable interplanar interactions and a weaker on-site Coulomb interaction compared to similar layered cobaltates.

Contribution

It provides the first detailed analysis of Sr0.35CoO2's electronic structure using LSDA and LSDA+U calculations, highlighting differences from NaxCoO2.

Findings

Presence of c-dispersions in Co-derived bands

On-site Coulomb interaction U is less than 3 eV

Electronic structure shows significant interplanar interaction

Abstract

The electronic structure of Sr0.35CoO2, structurally analogous to the layered NaxCoO2, 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-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 5eV to 8eV) in the NaxCoO2 materials.