Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconductivity at 33 - 37 K in $ALn_2$Fe$_4$As$_4$O$_2$ ($A$ = K and
  Cs; $Ln$ = Lanthanides)   We have synthesized 10 new iron oxyarsenides, K$Ln_2$Fe$_4$As$_4$O$_2$ ($Ln$
= Gd, Tb, Dy, and Ho) and Cs$Ln_2$Fe$_4$As$_4$O$_2$ ($Ln$ = Nd, Sm, Gd, Tb, Dy,
and Ho), with the aid of lattice-match [between $A$Fe$_2$As$_2$ ($A$ = K and
Cs) and $Ln$FeAsO] approach. The resultant compounds possess hole-doped
conducting double FeAs layers, [$A$Fe$_4$As$_4$]$^{2-}$, that are separated by
the insulating [$Ln_2$O$_2$]$^{2+}$ slabs. Measurements of electrical
resistivity and dc magnetic susceptibility demonstrate bulk superconductivity
at $T_\mathrm{c}$ = 33 - 37 K. We find that $T_\mathrm{c}$ correlates with the
axis ratio $c/a$ for all 12442-type superconductors discovered. Also,
$T_\mathrm{c}$ tends to increase with the lattice mismatch, implying a role of
lattice instability for the enhancement of superconductivity.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn