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.

Figure 1

(Color online) (a) Waterfall plot and (b) contour plot of the magnetotransmission resonance spectra from 0.25 to 11.5 T. Spectra are the ratios of the transmission at zero field $\left[T\left(0\right)\right]$ to the transmission at field $\left[T\left(B\right)\right]$ so that decreases in transmission due to absorption appear as peaks. A strong absorption obscures the spectra around 57 meV.

Figure 2

(Color online) (a) Plot of the observed transition energies as a function of magnetic field. The black dashed lines represent fitting to the transitions from Nakao’s (Ref. 27) calculations. The solid symbols represent resonance positions measured in Doezema et al. (Ref. 19). (b) Same data with red solid lines represent fitting using the method described in text.

Figure 3

(Color online) Interband transitions at high magnetic field as observed by Orlita et al. (Ref. 9) (solid symbols) compared to the approach used in the text (red solid lines) and the calculations of Nakao (Ref. 27) extended from 15 to 25 T using an adjusted the bilayer formula (black dashed lines). Data from the present work are shown as open symbols.

Figure 4

(Color online) Landau energies as a function of magnetic field calculated using the asymmetric bilayer model (solid line) and from Nakao’s SWM model (Ref. 27) (dotted line).