Dirac fermions at the H point of graphite: magnetotransmission studies.
We report on far infrared magnetotransmission measurements on a thin graphite sample prepared by exfoliation of highly oriented pyrolytic graphite. In a magnetic field, absorption lines exhibiting a blueshift proportional to sqrt[B] are observed. This is a fingerprint for massless Dirac holes at the H point in bulk graphite. The Fermi velocity is found to be c[over ] =( 1.02+/-0.02) x 10(6) m/s and the pseudogap |Delta| at the H point is estimated to be below 10 meV. Although the holes behave to a first approximation as a strictly 2D gas of Dirac fermions, the full 3D band structure has to be taken into account to explain all the observed spectral features.
Orlita
M
M
Grenoble High Magnetic Field Laboratory, CNRS, BP 166, F-38042 Grenoble Cedex 09, France. orlita@karlov.mff.cuni.cz
Faugeras
C
C
Martinez
G
G
Maude
D K
DK
Sadowski
M L
ML
Potemski
M
M