Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exploiting Aharonov-Bohm oscillations to probe Klein tunneling in
  tunable pn-junctions in graphene   One of the unique features of graphene is that the Fermi wavelength of its
charge carriers can be tuned electrostatically over a wide range. This allows
in principle to tune the transparency of a pn-junction electrostatically, as
this depends on the ratio between the physical extension of the junction and
the electron wavelength, i.e. on the effective width of the junction itself.
However, this simple idea - which would allow to switch smoothly between a
Veselago lens and a Klein-collimator - has proved to be difficult to
demonstrate experimentally because of the limited amount of
independently-tunable parameters available in most setups. In this work, we
present transport measurements in a quasi-ballistic Aharonov-Bohm graphene ring
with gate tunable pn-junctions in one arm, and show that the interference
patterns provide unambiguous information on the Klein tunneling efficiency and
on the junctions effective width. We find a gate-controlled transparency of the
pn-junctions ranging from 35-100%. Our results are in excellent agreement with
a semiclassical description.

33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex