Magnetoabsorption study of Landau levels in graphite

We report far-infrared magnetoabsorption measurements of thin graphite samples exfoliated from highly ordered pyrolytic graphite showing transitions originating from the K and the H points. For the K point, both cyclotron resonance and interband transitions are measured which are not described well by the currently accepted values of the parameters in the Slonczewski-Weiss-McClure tight-binding model. We demonstrate that the observed data can be better described using an effective bilayer graphite model which has been modified to include an electron-hole asymmetry.