Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Excitonic linewidth approaching the homogeneous limit in MoS2 based van
  der Waals heterostructures : accessing spin-valley dynamics   The strong light matter interaction and the valley selective optical
selection rules make monolayer (ML) MoS2 an exciting 2D material for
fundamental physics and optoelectronics applications. But so far optical
transition linewidths even at low temperature are typically as large as a few
tens of meV and contain homogenous and inhomogeneous contributions. This
prevented in-depth studies, in contrast to the better-characterized ML
materials MoSe2 and WSe2. In this work we show that encapsulation of ML MoS2 in
hexagonal boron nitride can efficiently suppress the inhomogeneous contribution
to the exciton linewidth, as we measure in photoluminescence and reflectivity a
FWHM down to 2 meV at T = 4K. This indicates that surface protection and
substrate flatness are key ingredients for obtaining stable, high quality
samples. Among the new possibilities offered by the well-defined optical
transitions we measure the homogeneous broadening induced by the interaction
with phonons in temperature dependent experiments. We uncover new information
on spin and valley physics and present the rotation of valley coherence in
applied magnetic fields perpendicular to the ML.

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The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc