Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by
  Optically Pumped NMR   Optically pumped nuclear magnetic resonance (OPNMR) measurements were
performed in two different electron-doped multiple quantum well samples near
the fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra
provide evidence that spin-reversed charged excitations of the nu=1/3 ground
state are localized over the NMR time scale of ~40 microseconds. Furthermore,
by varying NMR pulse parameters, the electron spin temperature (as measured by
the Knight shift) could be driven above the lattice temperature, which shows
that the value of the electron spin-lattice relaxation time lies between 100
microseconds and 500 milliseconds at nu=1/3.

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The categories of this paper are: supr-con
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
22
The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: eess
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas