Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electron-hole collision limited transport in charge-neutral bilayer
  graphene   Ballistic transport occurs whenever electrons propagate without collisions
deflecting their trajectory. It is normally observed in conductors with a
negligible concentration of impurities, at low temperature, to avoid
electron-phonon scattering. Here, we use suspended bilayer graphene devices to
reveal a new regime, in which ballistic transport is not limited by scattering
with phonons or impurities, but by electron-hole collisions. The phenomenon
manifests itself in a negative four-terminal resistance that becomes visible
when the density of holes (electrons) is suppressed by gate-shifting the Fermi
level in the conduction (valence) band, above the thermal energy. For smaller
densities transport is diffusive, and the measured conductivity is reproduced
quantitatively, with no fitting parameters, by including electron-hole
scattering as the only process causing velocity relaxation. Experiments on a
trilayer device show that the phenomenon is robust and that transport at charge
neutrality is governed by the same physics. Our results provide a textbook
illustration of a transport regime that had not been observed previously and
clarify the nature of conduction through charge-neutral graphene under
conditions in which carrier density inhomogeneity is immaterial. They also
demonstrate that transport can be limited by a fully electronic mechanism,
originating from the same microscopic processes that govern the physics of
Dirac-like plasmas.

14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs