Electron correlation and Fermi surface topology of Na_xCoO₂

2005/03/31 by Sen Zhou, Meng Gao, Hong Ding +2
Physics and Astronomy · #cond-mat.str-el

paper · pdf · doi:10.1103/physrevlett.94.206401

published as Phys. Rev. Lett. 94, 206401 (2005) · 5 pages, 4 figures, revtex4; minor changes, to be published in Phys. Rev. Lett

arxiv created 2005/04/28 · arxiv updated 2009/12/01

Abstract

The electronic structure of Na_xCoO₂ revealed by recent photoemission experiments shows important deviations from band theory predictions. The six small Fermi surface pockets predicted by LDA calculations have not been observed as the associated e_g^′ band fails to cross the Fermi level for a wide range of sodium doping concentration x. In addition, significant bandwidth renormalizations of the t_2g complex have been observed. We show that these discrepancies are due to strong electronic correlations by studying the multi-orbital Hubbard model in the Hartree-Fock and strong-coupling Gutzwiller approximation. The quasiparticle dispersion and the Fermi surface topology obtained in the presence of strong local Coulomb repulsion are in good agreement with experiments.

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