Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconductivity-induced transverse plasma mode and phonon anomaly in
  the $c$-axis response of the bilayer compound RbCa$_2$Fe$_4$As$_4$F$_2$   With infrared spectroscopy we studied the out-of-plane ($c$-axis) response of
the iron arsenide superconductor ACa$_2$Fe$_4$As$_4$F$_2$ (A = Rb,Cs) which has
a bilayer structure similar to the high $T_c$ cuprates YBa$_2$Cu$_3$O$_7$
(YBCO) and Bi$_2$Sr$_2$CaCu$_2$O$_8$ (Bi2212). In analogy to the cuprates, we
observe a superconductivity-induced transverse plasma mode (tPM) and a phonon
anomaly that are both signatures of local electric field effects that arise
from a large difference between the local conductivities in the intra- and
inter-bilayer regions. Using a multilayer model developed for the cuprates, we
obtain a good description of the $c$-axis response and derive the local
conductivities at $T \simeq T_c$ of $\sigma_1^{\mathrm{bl}}(\omega \rightarrow
0) \simeq$ 1\,000 $\Omega^{-1}\mathrm{cm}^{-1}$ and
$\sigma_1^{\mathrm{int}}(\omega \rightarrow 0) \simeq$ 15
$\Omega^{-1}\mathrm{cm}^{-1}$, respectively, that are similar to the ones
previously found in underdoped YBCO. Different from the cuprates, we find no
evidence of a normal state pseudogap in terms of a partial suppression of the
low-energy electronic states that sets in already well above $T_c$. There is
also no clear sign of an onset of precursor superconducting pairing
correlations well above $T_c \simeq$ 30~K. This highlights that the pseudogap
and the precursor superconducting pairing well above $T_c$ are unique features
of the cuprates with their strong electronic correlations and, for example, not
just the result of a strongly anisotropic electronic response due to the
layered crystal structure.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs