Location of Electron and Hole Carriers in Graphite from Laser Magnetoreflection Data

Magnetoreflection experiments have been carried out on pyrolytic graphite using circularly polarized radiation from an infrared gas laser source. From a preliminary analysis of the data we find that the carriers at point $K$ in the Brillouin zone are electrons rather than holes. Additional support for this conclusion is obtained from a reexamination of the cyclotron-resonance data of Galt, Yager, and Dail.