High field magneto-transmission investigation of natural graphite
  Magneto-transmission measurements in magnetic fields in the range B=20-60T have been performed to probe the H and K-point Landau level transitions in natural graphite. At the H-point, two series of transitions, whose energy evolves as $\sqrt{B}$ are observed. A reduced Slonczewski, Weiss and McClure (SWM) model with only two parameters to describe the intra-layer (gamma0) and inter-layer (gamma1) coupling correctly describes all observed transitions. Polarization resolved measurements confirm that the observed apparent splitting of the H-point transitions at high magnetic field cannot be attributed to an asymmetry of the Dirac cone. 
N. Ubrig, P. Plochocka, P. Kossacki, M. Orlita, D. K. Maude, O.   Portugall, and G. L. J. A. Rikken
cond-mat.mes-hall cond-mat.other