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Order and disorder in the triangular-lattice t-J-V model at 2/3 electron density

W. Zheng·J. Oitmaa·C. J. Hamer·R. R. P. Singh
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Abstract

Motivated by the recent discovery of superconductivity in Na$_x$CoO$_2\cdot y$H$_2$O, we use series expansion methods and cluster mean-field theory to study spontaneous charge order, Neel order, ferromagnetic order, dimer order and phase-separation in the triangular-lattice t-J-V model at 2/3 electron density. We find that for t<0, the charge ordered state, with electrons preferentially occupying a honeycomb lattice, is very robust. Quite surprisingly, hopping to the third sublattice can even enhance Neel order. At large negative t and small V, the Nagaoka ferromagnetic state is obtained. For large positive t, charge and Neel order vanish below a critical V, giving rise to an itinerant antiferromagnetically correlated state.

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W. Zheng, J. Oitmaa, C. J. Hamer, R. R. P. Singh. 2004-03-30. Order and disorder in the triangular-lattice t-J-V model at 2/3 electron density. https://doi.org/10.1103/physrevb.70.020504

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