Can Disorder Alone Destroy the ${e}_{g}^{\ensuremath{'}}$ Hole Pockets of ${\mathrm{Na}}_{x}{\mathrm{CoO}}_{2}$? A Wannier Function Based First-Principles Method for Disordered Systems

Can Disorder Alone Destroy the $e_{g}^{'}$ Hole Pockets of ${Na}_{x} {CoO}_{2}$ ? A Wannier Function Based First-Principles Method for Disordered Systems

Tom Berlijn, Dmitri Volja, and Wei Ku (顧威)

Phys. Rev. Lett. 106, 077005 – Published 18 February 2011

Abstract

We investigate from first principles the proposed destruction of the controversial $e_{g}^{'}$ pockets in the Fermi surface of ${Na}_{x} {CoO}_{2}$ due to Na disorder, by calculating its $k$ -dependent configuration-averaged spectral function $⟨ A (k, ω) ⟩$ . To this end, a Wannier function-based method is developed that treats the effects of disorder beyond the mean field. Remarkable spectral broadenings of order $\sim 1 eV$ are found for the oxygen orbitals, possibly explaining their absence in the experiments. In contradiction with the current claim, however, the $e_{g}^{'}$ pockets remain almost perfectly coherent. The developed method is expected to also generate exciting opportunities in the study of the countless functional materials that owe their important electronic properties to disordered dopants.

Received 7 April 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.077005

Authors & Affiliations

Tom Berlijn, Dmitri Volja^*, and Wei Ku (顧威)

Physics Department, State University of New York, Stony Brook, New York 11790, USA
Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, New York 11973, USA