Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charged Impurity Scattering in Graphene   Since the experimental realization of graphene1, extensive theoretical work
has focused on short-range disorder2-5, ''ripples''6, 7, or charged
impurities2, 3, 8-13 to explain the conductivity as a function of carrier
density sigma_(n)[1,14-18], and its minimum value sigma_min near twice the
conductance quantum 4e2/h[14, 15, 19, 20]. Here we vary the density of charged
impurities nimp on clean graphene21 by deposition of potassium in ultra high
vacuum. At non-zero carrier density, charged impurity scattering produces the
ubiquitously observed1, 14-18 linear sigma_(n) with the theoretically-predicted
magnitude. The predicted asymmetry11 for attractive vs. repulsive scattering of
Dirac fermions is observed. Sigma_min occurs not at the carrier density which
neutralizes nimp, but rather the carrier density at which the average impurity
potential is zero10. Sigma_min decreases initially with nimp, reaching a
minimum near 4e2/h at non-zero nimp, indicating that Sigma_min in present
experimental samples does not probe Dirac-point physics14, 15, 19, 20 but
rather carrier density inhomogeneity due to the impurity potential3, 9, 10.

11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys