Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modelling the Berezinskii-Kosterlitz-Thouless Transition in the
  NiGa_2S_4   In the two-dimensional superfluidity, the proliferation of the vortices and
the anti-vortices results in a new class of phase transition,
Berezinskii-Kosterlitz-Thouless (BKT) transition. This class of the phase
transitions is also anticipated in the two-dimensional magnetic systems.
However, its existence in the real magnetic systems still remains mysterious.
Here we propose a phenomenological model to illustrate that the novel
spin-freezing transition recently uncovered in the NMR experiment on the
NiGa_2S_4 compound is the BKT-type. The novel spin-freezing state observed in
the NiGa_2S_4 possesses the power-law decayed spin correlation.

27
The categories of this paper are: comp-gas
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat