Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bound state of 4$f$-excitation and magnetic resonance in unconventional
  superconductors   We analyze the influence of unconventional superconductivity on crystalline
electric field (CEF) excitations of rare earth ions in novel superconductors.
We show that resonant magnetic excitations of the conduction electrons that
have been observed in these systems below T$_c$ may result in the formation of
the bound state in the 4$f$-electron susceptibility. This occurs at energies
well below the CEF excitation energy. The effect is discussed as a function of
temperature and the strength of the coupling between the 4$f$ and
$d$-electrons. We argue that these effects may be present in the layered
cuprates and ferropnictides which contain rare-earth ions.

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The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
18
The categories of this paper are: econ
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph