Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Possible effects of charge frustration in Na$_x$CoO$_2$: bandwidth
  suppression, charge orders and resurrected RVB superconductivity   Charge frustration due to further neighbor Coulomb repulsion can have
dramatic effects on the electronic properties of Na$_x$CoO$_2$ in the full
doping range. It can significantly reduce the effective mobility of the charge
carriers, leading to a low degeneracy temperature $\epsilon_F \lesssim T$. Such
strongly renormalized Fermi liquid has rather unusual properties--from the
point of view of the ordinary metals with $\epsilon_F \gg T$--but similar to
the properties that are actually observed in the Na$_x$CoO$_2$ system. For
example, we show that the anomalous thermopower and Hall effect observed in
Na$_{0.7}$CoO$_2$ may be interpreted along these lines. If the repulsion is
strong, it can also lead to charge order; nevertheless, away from the
commensurate dopings, the configurational constraints allow some mobility for
the charge carriers, i.e., there remains some ``metallic'' component. Finally,
the particularly strong bandwidth suppression around the commensurate $x=1/3$
can help resurrect the RVB superconductivity, which would otherwise not be
expected near this high doping. These suggestions are demonstrated specifically
for a $tJ$-like model with an additional nearest neighbor repulsion.

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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: q-alg
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: math