Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dirac fermion reflector by ballistic graphene sawtooth-shaped npn
  junctions   We have realized a Dirac fermion reflector in graphene by controlling the
ballistic carrier trajectory in a sawtooth-shaped npn junction. When the
carrier density in the inner p-region is much larger than that in the outer
n-regions, the first straight np interface works as a collimator and the
collimated ballistic carriers can be totally reflected at the second zigzag pn
interface. We observed clear resistance enhancement around the np+n regime,
which is in good agreement with the numerical simulation. The tunable
reflectance of ballistic carriers could be an elementary and important step for
realizing ultrahigh-mobility graphene field effect transistors utilizing Dirac
fermion optics in the near future.

6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph