c-axis conduction in graphite intercalation compounds

Abstract

In an earlier paper, we introduced the concepts of phonon-assisted and impurity-assisted hopping processes to explain the c-axis resistivity in graphite intercalation compounds (GIC’s). A different theory was proposed by Shimamura. Both theories provide a qualitative explanation for the observed behaviors in low-stage compounds but they cannot account for the high-temperature behavior in high-stage compounds. In this paper two new mechanisms are introduced. One is the interaction of the carriers with the LO phonons polarized along the c axis. This is important in low-stage compounds with large charge transfer. The other mechanism is the scattering of the carriers by stacking faults, which is important in high-stage compounds. By considering the mechanisms proposed previously by us and by Shimamura together with the new mechanism, we obtain a qualitative explanation for the temperature and stage dependences of the c-axis resistivity in GIC’s.