Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nematic Order by Disorder in Spin-2 BECs   The effect of quantum and thermal fluctuations on the phase diagram of spin-2
BECs is examined. They are found to play an important role in the nematic part
of the phase diagram, where a mean-field treatment of two-body interactions is
unable to lift the accidental degeneracy between nematic states. Quantum and
thermal fluctuations resolve this degeneracy, selecting the uniaxial nematic
state, for scattering lengths $a_4>a_2$, and the square biaxial nematic state
for $a_4<a_2$. Paradoxically, the fluctuation induced order is stronger at
higher temperatures, for a range of temperatures below $T_c$. For the
experimentally relevant cases of spin-2 $^{87}$Rb and $^{23}$Na, we argue that
such fluctuations could successfully compete against other effects like the
quadratic Zeeman field, and stabilize the uniaxial phase for experimentally
realistic conditions. A continuous transition of the Ising type from uniaxial
to square biaxial order is predicted on raising the magnetic field. These
systems present a promising experimental opportunity to realize the `order by
disorder' phenomenon.

31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th