Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nodeless superconductivity and the peak effect in the
  quasi-skutterudites $\mathrm{Lu}_3\mathrm{Os}_4\mathrm{Ge}_{13}$ and
  $\mathrm{Y}_3\mathrm{Ru}_4\mathrm{Ge}_{13}$   We report an investigation of the superconducting states of
$\mathrm{Lu}_3\mathrm{Os}_4\mathrm{Ge}_{13}$ and
$\mathrm{Y}_3\mathrm{Ru}_4\mathrm{Ge}_{13}$ single crystals by measurements of
the electrical resistivity, ac susceptibility and London penetration depth. The
analysis of the penetration depth and the derived superfluid density indicates
the presence of nodeless superconductivity and suggest that there are multiple
superconducting gaps in both materials. Furthermore, ac susceptibility
measurements of both compounds display the peak effect in the low temperature
region of the $H-T$ phase diagram. This anomalous increase of the critical
current with field gives an indication of a change of the arrangement of flux
lines in the mixed state, as found in some of the isostructural stannide
materials.

18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
1
The categories of this paper are: cs
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc