Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Temperature Dependent Valley Relaxation Dynamics in Single Layer WS2
  Measured Using Ultrafast Spectroscopy   We measured the lifetime of optically created valley polarization in single
layer WS2 using transient absorption spectroscopy. The electron valley
relaxation is very short (< 1ps). However the hole valley lifetime is at least
two orders of magnitude longer and exhibits a temperature dependence that
cannot be explained by single carrier spin/valley relaxation mechanisms. Our
theoretical analysis suggests that a collective contribution of two potential
processes may explain the valley relaxation in single layer WS2. One process
involves direct scattering of excitons from K to K' valleys with a spin
flip-flop interaction. The other mechanism involves scattering through spin
degenerate Gamma valley. This second process is thermally activated with an
Arrhenius behavior due to the energy barrier between Gamma and K valleys.

0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
18
The categories of this paper are: econ
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex