Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Strong-coupling superconductivity in layered nickel-based
  LaO$_{1-x}$F$_x$NiAs   A series of layered nickel-based LaO$_{1-x}$F$_x$NiAs compounds with x=0 to
0.15 are synthesized by solid state reactions. The pure LaONiAs exhibits bulk
superconductivity with Tc $\sim$ 2.75 K. Partial substitution of oxygen by
fluorine increases the transition temperature to $\sim 3.8$ K. The
LaO$_{0.9}$F$_{0.1}$NiAs sample shows a sharp superconducting transition and a
sharp specific heat jump at the critical temperature. The magnitude of the
specific heat jump is much larger than that expected from the weak-coupling BCS
theory, indicating that this superconductor is in the strong coupling regime.
Furthermore, the temperature dependence of the specific heat deviates strongly
from the theoretical result for the single-band s- or d-wave superconductor,
but shows some character of a multi-gap system.

11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics