C-Axis Thermoelectric Power of Graphite Intercalation Compounds with Iodine Monochrolide

Abstract

Thermoelectric power in the c-direction ( S c ) of iodine monochrolide-graphite intercalation compounds (ICl-GICs) exhibits a gradual slope change around 80–100 K, though above and below the temperature range S c is nearly linearly temperature-dependent. This behavior implies that the major contribution to S c comes from the diffusion term ( S d ), and the absence of the phonon drag term ( S p ) in contrast with the in-plane component ( S a ) is due to the very weak interlayer interaction. The slope change is ascribed to the change of the energy dependence of Γ ph ( E ) with temperature, where Γ ph ( E ) is the scattering rate of carriers due to the in-plane phonons. Γ ph ( E ) and p ph ≡- E (d/d E ) log Γ ph ( E ), which are included in the expression of S c , are calculated. The calculation can provide a qualitative explanation of the observed result of stage-1 compound.