  The low-energy band structure of Bernal-stacked hexlayer graphene was
investigated by the measuring transport properties of high-mobility graphene
samples equipped with a top and a bottom gate electrode at low temperature and
in a magnetic field. By analyzing the Landau fan diagram, it was found that the
hexlayer graphene consisted of three different bilayer-like bands that overlap
and form a semimetal. The electronic band structure was significantly
influenced by the perpendicular electric field generated by the top and bottom
gate voltages. The Not fan diagram shows splitting of zero-mode Landau levels,
while also the top and bottom gate voltage dependence of the resistivity at
zero magnetic field shows ridge-like structure, similar to the one recently
found in tetralayer graphene. It is shown that the ridge structure originates
from the band structure of the Bernalstacked hexlayer graphene. Most of the
ridges originate from the bottoms of the bilayer-like bands, and a few ridges
originate from the energy gap structures which locally close due to trigonal
warping and expected to form mini-Dirac cones.
