Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge-ordering, commensurability and metallicity in the phase diagram
  of layered Na(x)CoO(2)   The phase diagram of non-hydrated Na(x)CoO(2) has been determined by changing
the Na content x using a series of chemical reactions. As x increases from 0.3,
the ground state goes from a paramagnetic metal to a charge-ordered insulator
(at x=1/2) to a `Curie-Weiss metal' (around 0.70), and finally to a weak-moment
magnetically ordered state (x>0.75). The unusual properties of the state at 1/2
(including particle-hole symmetry at low T and enhanced thermal conductivity)
are described. The strong coupling between the Na ions and the holes is
emphasized.

33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat