Graphite from the viewpoint of Landau level spectroscopy: an effective graphene bilayer and monolayer.
We describe an infrared transmission study of a thin layer of bulk graphite in magnetic fields up to B=34 T. Two series of absorption lines whose energy scales as sqrt[B] and B are present in the spectra and identified as contributions of massless holes at the H point and massive electrons in the vicinity of the K point, respectively. We find that the optical response of the K point electrons corresponds, over a wide range of energy and magnetic field, to a graphene bilayer with an effective interlayer coupling 2gamma_{1}, twice the value for a real graphene bilayer, which reflects the crystal ordering of bulk graphite along the c axis. The K point electrons thus behave as massive Dirac fermions with a mass enhanced twice in comparison to a true graphene bilayer.
Orlita
M
M
Laboratoire National des Champs Magnétiques Intenses, CNRS, BP 166, F-38042 Grenoble Cedex 09, France. orlita@karlov.mff.cuni.cz
Faugeras
C
C
Schneider
J M
JM
Martinez
G
G
Maude
D K
DK
Potemski
M
M