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TT: Fachverband Tiefe Temperaturen

TT 22: CE: Low-dimensional Systems - Materials 2

TT 22.8: Vortrag

Dienstag, 15. März 2011, 12:30–12:45, HSZ 304

Nature of electronic correlations in strongly doped Na_xCoO₂ — •Christoph Piefke¹, Lewin Boehnke¹, Antoine Georges², and Frank Lechermann¹ — ¹I. Institut für Theoretische Physik, Universität Hamburg, Germany — ²CPHT, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France

With the combination of the rotationally invariant slave-boson mean-field theory (RISB) [1,2] and the local-density approximation (LDA) to density functional theory, the phase diagram of layered sodium cobaltate Na_xCoO₂ is investigated in the high-doping regime close to zero temperature [3]. This system represents one of the rare natural examples of a dopable strongly correlated triangular lattice. Utilizing a tailored realistic single-band approach in a cellular-cluster framework, we investigate the effect of electronic correlations with doping until the band-insulating (x=1) limit. The experimentally verified [4] in-plane crossover from antiferromagnetic tendencies at low x towards ferromagnetic order for x>0.75 is revealed with an on-site Hubbard interaction. Relevant charge-ordering physics in the system is modelled via an additional inter-site Coulomb interaction V on an effective kagomé lattice, as observed in experiment [5].
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