We present the results of THz, infrared and magneto-optical measurements performed on graphite nanoplatelet films as a function of temperature (4.2-300 K) and magnetic field (0-17.5 T). An effective medium analysis of the low-energy spectral response indicates that the nanoplatelet material is well described by a Drude function plus two infrared absorption bands. Interestingly, the Drude plasma frequency (∼1675 cm-1) decreases slowly with temperature, whereas the carrier scattering rate (∼175 cm-1) is temperature independent. Furthermore, measurements in an applied magnetic field at 4.2K show that a large portion of the Drude spectral weight is transferred to finite frequency features corresponding to various Landau-level transitions. Some of these transition energies scale as p B, as expected for Dirac-like quasi-particles in graphene and observed in other graphene-like materials. Thus, our results are consistent with recent theoretical calculations indicating that the spectrum of multilayer graphene can be decomposed into subsystems effectively identical to monolayer or bilayer graphene.
ASJC Scopus subject areas
- Physics and Astronomy(all)