Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of angle-dependent transmission of Dirac electrons in
  graphene hetero junctions   The relativistic nature of charge carriers in graphene is expected to lead to
an angle- dependent transmission through a potential barrier, where Klein
tunneling involves annihilation of an electron and a hole at the edges of the
barrier. The signatures of Klein tunneling have been observed in gated graphene
devices, but the angle dependence of the transmission probability has not been
directly observed. Here we show measurements of the angle-dependent
transmission through quasi-ballistic graphene heterojunctions with straight and
angled leads, in which the barrier height is controlled by a shared gate
electrode. Using a balanced differential measurement technique, we isolate the
angle-dependent contribution to the resistance from other angle-insensitive,
gate-dependent and device-dependent effects. We find large oscillations in the
transmission as a function of the barrier height in the case of Klein tunneling
at a 45 deg angle, as compared to normal incidence. Our results are consistent
with the model that predicts oscillations of the transmission probability due
to interference of chiral carriers in a ballistic barrier. The observed angle
dependence is the key element behind focusing of electrons and the realization
of a Veselago lens in graphene.

5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga