Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Varying Electronic Coupling at Graphene-Copper Interfaces Probed with
  Raman Spectroscopy   As the synthesis of graphene on copper became one of the primary preparation
methods for both fundamental research and industrial application, Raman spectra
of graphene/Cu systems need to be quantitatively understood regarding how their
interactions affect the electronic structure of graphene. Using
multi-wavelength Raman spectroscopy, we investigated three types of graphene
bound on Cu: graphene grown on Cu foils and Cu film/SiO2, and Cu-evaporated
exfoliated graphene. 2D peak frequencies of the first two samples were ~17 cm-1
higher than expected for 1.96 eV excitation even when the effect of strain was
considered. More notably, the upshift in 2D decreased with increasing
excitation energy. Based on control experiments using Cu-evaporated graphene,
we revealed that the spectral anomaly was induced by environment-dependent
nonlinear dispersion in the electronic bands of graphene and determined the
degree of the electronic modification. We also showed that the large upshifts
of G and 2D peaks originating from differential thermal expansion of Cu could
be significantly reduced by backing Cu films with dielectric substrates of
insignificant thermal expansion. The quantitative analysis of electronic
coupling between graphene and Cu presented in this study will be highly useful
in characterizing as-grown graphene and possibly in other forms.

15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex