Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nodeless superconductivity in the noncentrosymmetric Mo$_3$Rh$_2$N
  superconductor: a $\mu$SR study   The noncentrosymmetric superconductor Mo$_3$Rh$_2$N, with $T_c = 4.6$ K,
adopts a $\beta$-Mn-type structure (space group $P$4$_1$32), similar to that of
Mo$_3$Al$_2$C. Its bulk superconductivity was characterized by magnetization
and heat-capacity measurements, while its microscopic electronic properties
were investigated by means of muon-spin rotation and relaxation ($\mu$SR). The
low-temperature superfluid density, measured via transverse-field (TF)-$\mu$SR,
evidences a fully-gapped superconducting state with $\Delta_0 = 1.73
k_\mathrm{B}T_c$, very close to 1.76 $k_\mathrm{B}T_c$ - the BCS gap value for
the weak coupling case, and a magnetic penetration depth $\lambda_0 = 586$ nm.
The absence of spontaneous magnetic fields below the onset of
superconductivity, as determined by zero-field (ZF)-$\mu$SR measurements, hints
at a preserved time-reversal symmetry in the superconducting state. Both TF-and
ZF-$\mu$SR results evidence a spin-singlet pairing in Mo$_3$Rh$_2$N.

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The categories of this paper are: q-bio
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The categories of this paper are: supr-con
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: astro-ph
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: physics
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: stat
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The categories of this paper are: q-fin