Dynamical mean field theory of an effective three-band model for NaxCoO2

Abstract

We derive an effective Hamiltonian for highly correlated t2g states centered at the Co sites of NaxCoO2. The essential ingredients of the model are an O mediated hopping, a trigonal crystal-field splitting, and on-site effective interactions derived from the exact solution of a multiorbital model in a CoO6 cluster, with parameters determined previously. The effective model is solved by dynamical mean field theory. We obtain a Fermi surface and electronic dispersion that agrees well with angle-resolved photoemission spectra. Our results also elucidate the origin of the "sinking pockets" in different doping regimes. © 2009 The American Physical Society.