Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultrafast dynamics in the presence of antiferromagnetic correlations in
  electron-doped cuprate La$_{2-x}$Ce$_x$CuO$_{4\pm\delta}$   We used femtosecond optical pump-probe spectroscopy to study the photoinduced
change in reflectivity of thin films of the electron-doped cuprate
La$_{2-x}$Ce$_x$CuO$_4$ (LCCO) with dopings of x$=$0.08 (underdoped) and
x$=$0.11 (optimally doped). Above T$_c$, we observe fluence-dependent
relaxation rates which onset at a similar temperature that transport
measurements first see signatures of antiferromagnetic correlations. Upon
suppressing superconductivity with a magnetic field, it is found that the
fluence and temperature dependence of relaxation rates is consistent with
bimolecular recombination of electrons and holes across a gap (2$\Delta_{AF}$)
originating from antiferromagnetic correlations which comprise the pseudogap in
electron-doped cuprates. This can be used to learn about coupling between
electrons and high-energy ($\omega>2\Delta_{AF}$) excitations in these
compounds and set limits on the timescales on which antiferromagnetic
correlations are static.

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The categories of this paper are: math
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The categories of this paper are: nucl-th
33
The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: solv-int
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The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
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The categories of this paper are: nlin
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The categories of this paper are: gr-qc
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The categories of this paper are: eess