Si Wu, Matthew Killi, Arun Paramekanti
Superlattices (SLs) in monolayer and bilayer graphene lead to extra finite
energy and zero energy Dirac fermions with tunable anisotropic velocities. We
theoretically show that transport in a weak perpendicular (orbital) magnetic
field allows one to not only probe the number of Dirac points but also yields
further information about their dispersion. We find that a moderate magnetic
field in monolayer graphene can lead to a strong reversal of the transport
anisotropy imposed by the SL potential, due to the SL induced dispersion of the
zero energy Landau levels. This effect may find useful device applications. For
bilayer graphene, we discuss the structure of Landau level wave functions and
local density of states in the presence of a uniform bias, as well as in the
presence of a kink in the bias which leads to topologically bound 'edge
states'. We consider implications for valley filtering and impurity induced
breakdown of the quantum Hall effect in bilayer graphene.
View original:
http://arxiv.org/abs/1202.1441
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