Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Low-lying excitations at the rare-earth site due to rattling motion in
  the filled skutterudite LaOs_4Sb_{12} revealed by ^{139}La NMR and
  ^{121/123}Sb NQR   We report experimental results of nuclear magnetic resonance (NMR) at the La
site and nuclear quadrupole resonance (NQR) at the Sb site in the filled
skutterudite LaOs$_4$Sb$_{12}$. We found that the nuclear spin-lattice
relaxation rate divided by temperature $1/T_1T$ at the La site exhibits a
different temperature dependence from that at the Sb site. Although $1/T_1T$ at
the Sb site is explained by the Korringa mechanism, $1/T_1T$ at the La site
exhibits a broad maximum around 50 K, showing the presence of an additional
contribution at the La site. The additional low-lying excitations observed at
the La site can be understood with the relaxation from anharmonic phonons due
to the rattling motion of the La atoms.

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The categories of this paper are: funct-an
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The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: cmp-lg