Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ba8CoNb6O24: a spin-1/2 triangular-lattice Heisenberg antiferromagnet in
  the 2D limit   The perovskite Ba8CoNb6O24 comprises equilateral effective spin-1/2 Co2+
triangular layers separated by six non-magnetic layers. Susceptibility,
specific heat and neutron scattering measurements combined with
high-temperature series expansions and spin-wave calculations confirm that
Ba8CoNb6O24 is basically a twodimensional (2D) magnet with no detectable spin
anisotropy and no long-range magnetic ordering down to 0.06 K. In other words,
Ba8CoNb6O24 is very close to be a realization of the paradigmatic spin-1/2
triangular Heisenberg model, which is not expected to exhibit symmetry breaking
at finite temperature according to the Mermin and Wagner theorem.

15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th