Magnetoplasmons in simple hexagonal graphite

Abstract

Magneto-electronic Coulomb excitations in simple hexagonal graphite (SHG) are studied within the random-phase approximation. They strongly depend on the direction and the magnitude of the transferred momentum q, and the magnetic field strength. The plasmon frequency dispersion in the perpendicular component q_z in the primitive unit cell and its parallel component q_‖ are very different from each other. The former shows only one prominent peak. The plasmon frequency increases with q_z, while the intensity of the plasmon peak exhibits the opposite behavior. The latter presents many plasmon peaks. Moreover, the threshold frequency of the loss spectrum for SHG is higher than that of monolayer graphene. As the field strength increases, the plasmon peaks are intensified. The group velocity for plasmon propagation along is typically positive for a fixed field strength. The q_z-dependence of the plasmon frequency is gradually reduced with an increased field strength. Graphite somewhat differs from graphene in magneto-electronic excitations, including the intensity, number and frequency of magnetoplasmons.