Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nuclear Spin-Lattice Relaxation Induced by Thermally Fluctuating Flux
  Lines in Type-II Superconductors   Thermal motion of the flux lines (FL) gives rise to fluctuating magnetic
fields. These dynamic fields couple to the nuclei in the sample and relax the
nuclear spins. Based on a model of harmonic fluctuations, we provide a
theoretical description of the nuclear spin-lattice relaxation (NSLR) process
due to the fluctuating FLs in clean type-II superconductors. At low fields, the
calculated longitudinal relaxation rate $T_1^{-1}$ is enormously enhanced at
temperatures just below $T_c$. At intermediate fields, the resulting $T_1^{-1}$
exhibits a peak structure as a function of temperature, which is eventually
suppressed as the field is increased. The vibrational modes which have
components propagating along the FLs play an essential role in the $T_1^{-1}$
process.

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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys