The four-probe technique is used to measure the c-axis resistivity of various stages of ${\mathrm{FeCl}}_3$ acceptor graphite intercalated compounds. A comprehensive investigation of the resistivity behavior between room and liquid-helium temperatures for stages 2–5 and 9 and highly oriented pyrolytic graphite is presented. The data show a low-stage dependence where the resistivity increases with temperature, an intermediate stage where the temperature variation of the resistivity is small, and a high-stage dependence where the resistivity decreases with temperature. In our case, stage 5 plays the role of the intermediate stage. Stage 5 also exhibits the highest room-temperature resistivity. The c-axis resistivity data are analyzed in terms of the variable-range hopping-conduction model in parallel with band conduction.

• Received 28 December 1987

DOI:https://doi.org/10.1103/PhysRevB.38.680