  The electronic properties of bilayer graphene strongly depend on relative
orientation of the two atomic lattices. Whereas Bernal-stacked graphene is most
commonly studied, a rotational mismatch between layers opens up a whole new
field of rich physics, especially at small interlayer twist. Here we report on
magnetotransport measurements on twisted graphene bilayers, prepared by folding
of single layers. These reveal a strong dependence on the twist angle, which
can be estimated by means of sample geometry. At small rotation, superlattices
with a wavelength in the order of 10 nm arise and are observed by friction
atomic force microscopy. Magnetotransport measurements in this small-angle
regime show the formation of satellite Landau fans. These are attributed to
additional Dirac singularities in the band structure and discussed with respect
to the wide range of interlayer coupling models.
