Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unconventional spin freezing and fluctuations in the frustrated
  antiferromagnet NiGa2S4   Muon spin rotation (muSR) experiments reveal unconventional spin freezing and
dynamics in the two-dimensional (2D) triangular lattice antiferromagnet
NiGa2S4. Long-lived disordered Ni-spin freezing (correlation time > 10-6 s at 2
K) sets in below T_f = 8.5 +- 0.5 K with a mean-field-like temperature
dependence. The observed exponential temperature dependence of the muon spin
relaxation above T_f is strong evidence for 2D critical spin fluctuations. Slow
Ni spin fluctuations coexist with quasistatic magnetism at low temperatures but
are rapidly suppressed for fields > 10 mT, in marked contrast with the
field-independent specific heat. The muSR and bulk susceptibility data indicate
a well-defined 2D phase transition at T_f, below which NiGa2S4 is neither a
conventional magnet nor a singlet spin liquid.

15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom