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Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

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

TT 22.8: Talk

Tuesday, March 15, 2011, 12:30–12:45, HSZ 304

Nature of electronic correlations in strongly doped NaxCoO2 — •Christoph Piefke1, Lewin Boehnke1, Antoine Georges2, and Frank Lechermann11I. 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 NaxCoO2 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].
T. Li et al., PRB 40, 6817 (1989).
F. Lechermann et al., PRB 76, 155102 (2007).
C. Piefke et al., PRB 82, 165118 (2010).
G. Lang et al., PRB 78, 155116 (2008).
H. Alloul et al., EPL 85, 47006 (2009).

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