Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Symmetry governed valley-pseudospin textures of the full-zone excitonic
  bands of transition-metal dichalcogenide monolayers   Preserving a high degree of valley polarization of excitons in photo-excited
transition-metal dichalcogenide monolayers (TMD-MLs) is desirable for the
valley-based photonic applications, but widely recognized as a hard task
hindered by the intrinsic electron-hole exchange interaction. In this study, we
present a comprehensive investigation of valley-polarized finite-momentum
excitons in WSe$_2$-MLs over the entire Brillouin zone by solving the
density-functional-theory(DFT)-based Bethe-Salpeter equation (BSE) under the
guidance of symmetry analysis. We reveal that finite-momentum excitons are
actually in general well immune from the exchange-induced valley
depolarization, except for those with specific exciton momenta directionally
coincide with the axes associated with the $3\sigma_v$ and $3C_2'$ symmetries
in TMD-MLs. Governed by the symmetries, the valley pseudo-spin texture of the
full-zone exciton band in the momentum space is locally featured by individual
skyrmion-like structures where highly valley-polarized finite-momentum exciton
states are centred. Remarkably, we show that the high degrees of valley
polarizations of the finite-momentum exciton states are excellently well
transferable to the optical polarizations in the resulting phonon-assisted
photo-luminescences, suggesting the prospective usefulness of those
inter-valley excitons in valley-based photonics.

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The categories of this paper are: math
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: physics
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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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: econ
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The categories of this paper are: alg-geom