Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin fluctuations and pairing symmetry in A$_{x}$Fe$_{2-y}$Se$_{2}$:
  dual effect of the itinerant and the localized nature of electrons   We investigate the spin fluctuations and the pairing symmetry in
A$_{x}$Fe$_{2-y}$Se$_{2}$ by the fluctuation exchange approximation. Besides
the on-site interactions, the next-nearest-neighbor antiferromagnetic coupling
$J_{2}$ is also included. We find that both the itinerant and the localized
natures of electrons are important to describe the recent experimental results
of the spin fluctuations and the pairing symmetry. In particular, a small
$J_{2}$ coupling can change the pairing gap from the d-wave symmetry to the
s-wave symmetry. We have also studied the real-space structures of the gap
functions for different orbits in order to gain more insight on the nature of
the pairing mechanism.

17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex