Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spin States Protected from Intrinsic Electron-Phonon-Coupling Reaching
  100 ns Lifetime at Room Temperature in MoSe$_2$   We present time-resolved Kerr rotation measurements, showing spin lifetimes
of over 100 ns at room temperature in monolayer MoSe$_2$. These long lifetimes
are accompanied by an intriguing temperature dependence of the Kerr amplitude,
which increases with temperature up to 50 K and then abruptly switches sign.
Using ab initio simulations we explain the latter behavior in terms of the
intrinsic electron-phonon coupling and the activation of transitions to
secondary valleys. The phonon-assisted scattering of the photo-excited
electron-hole pairs prepares a valley spin polarization within the first few ps
after laser excitation. The sign of the total valley magnetization, and thus
the Kerr amplitude, switches as a function of temperature, as conduction and
valence band states exhibit different phonon-mediated inter-valley scattering
rates. However, the electron-phonon scattering on the ps time scale does not
provide an explanation for the long spin lifetimes. Hence, we deduce that the
initial spin polarization must be transferred into spin states which are
protected from the intrinsic electron-phonon coupling, and are most likely
resident charge carriers which are not part of the itinerant valence or
conduction band states.

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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: acc-phys
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The categories of this paper are: cs
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: atom-ph
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The categories of this paper are: astro-ph
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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: chao-dyn
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The categories of this paper are: gr-qc