Coulomb correlations do not fill the e'_g hole pockets in Na_{0.3}CoO_2

TL;DR

This study investigates whether local Coulomb interactions can explain the missing e'_g hole pockets in Na_{0.3}CoO_2, concluding they do not vanish due to Coulomb effects.

Contribution

The paper demonstrates through advanced simulations that Coulomb correlations do not eliminate the e'_g hole pockets in Na_{0.3}CoO_2, challenging previous hypotheses.

Findings

Coulomb interactions slightly modify e'_g pockets

e'_g pockets do not disappear with realistic Coulomb parameters

Results are consistent across multiple computational methods

Abstract

There exists presently considerable debate over the question whether local Coulomb interactions can explain the absence of the small e'_g Fermi surface hole pockets in photoemission studies of Na_{0.3}CoO_2. By comparing dynamical mean field results for different single particle Hamiltonians and exact diagonalization as well as quantum Monte Carlo treatments, we show that, for realistic values of the Coulomb energy U and Hund exchange J, the e'_g pockets can be slightly enhanced or reduced compared to band structure predictions, but they do not disappear.