Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 39: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles III (jointly with TT)
O 39.5: Talk
Wednesday, March 28, 2012, 11:30–11:45, HE 101
Strong correlations enhanced by charge-ordering in highly doped cobaltates — •Oleg Peil1, Antoine Georges2,3,4, and Frank Lechermann1 — 1I. Institut für Theoretische Physik, Universität Hamburg, D-20355 Hamburg, Germany — 2Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France — 3Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France — 4DPMC, Université de Genève, 24 Quai Ernest Ansermet, 1211 Genève 4, Suiss
Layered cobaltates represent a family of strongly correlated systems with quite unusual properties. In particular, they exhibit the strong mass and low-temperature-conductivity renormalization in the high-doping regime. We present an explanation for the puzzling spectral and transport properties of layered cobaltates close to the band-insulator limit, which relies on the key effect of charge ordering. Blocking a significant fraction of the lattice sites deeply modifies the electronic structure in a way that is shown to be quantitatively consistent with photoemission experiments. It also makes the system highly sensitive to interactions (especially to intersite ones), hence accounting for the strong correlations effects observed in this regime, such as the high effective mass and quasiparticle scattering rate. These conclusions are supported by a theoretical study of an extended Hubbard model with a realistic band structure on an effective kagome lattice.