SCREENING OF CHARGED IMPURITIES IN GRAPHITE-INTERCALATION COMPOUNDS

The screening problem has been studied here with the use of an analytically expressed dielectric function, which was calculated in accordance with the band structure of the graphite intercalation compounds. Due to the special band structure of this system, the screening has been found to be very effective at short distances from an impurity, and a strong but short-period Friedel oscillation also exists at large distances. These features are expected to have important effects on, for example, the resistivity and the ordering of impurities in the system. We have calculated the residual resistivity due to the scattering from charged impurities. Direct comparison with measured results has indicated that a small amount of such impurities could explain the observed resistivities in the stage-1 C-8M compounds (M for K, Rb, and Cs).