Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Variation of the fundamental band gap nature in curved two-dimensional
  WS2   We report a strain-induced direct-to-indirect band gap transition in
mechanically deformed WS2 monolayers (MLs). The necessary amount of strain is
attained by proton irradiation of bulk WS2 and the ensuing formation of
one-ML-thick, H2-filled domes. The electronic properties of the curved MLs are
mapped by spatially- and time-resolved micro-photoluminescence revealing the
mechanical stress conditions that trigger the variation of the band gap
character. This general phenomenon, also observed in MoS2 and WSe2, further
increases our understanding of the electronic structure of transition metal
dichalcogenide MLs and holds a great relevance for their optoelectronic
applications.

20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol