Effect of Dynamical Coulomb Correlations on the Fermi Surface of Na_0.3CoO_2

TL;DR

This paper investigates how dynamical Coulomb correlations influence the Fermi surface of Na_0.3CoO_2, revealing charge transfer effects that stabilize certain Fermi surface pockets contrary to experimental observations.

Contribution

It demonstrates the impact of dynamical mean field theory on understanding charge transfer and Fermi surface features in Na_0.3CoO_2, highlighting the role of correlations in electronic structure.

Findings

Charge transfer from e_g' to a_1g bands due to correlations

Stabilization of small e_g' Fermi surface pockets

Contradiction with angle-resolved photoemission data

Abstract

The t2g quasi-particle spectra of Na_0.3CoO_2 are calculated within the dynamical mean field theory. It is shown that as a result of dynamical Coulomb correlations charge is transfered from the nearly filled e_g' subbands to the a_1g band, thereby reducing orbital polarization among Co t2g states. Dynamical correlations therefore stabilize the small e_g' Fermi surface pockets, in contrast to angle-resolved photoemission data, which do not reveal these pockets.