M. Shayegan

Thermoelectric Properties of a Dilute Graphite Donor Intercalation Compound

Data on the in-plane thermal conductivity and thermoelectric power of a stage-5 potassium donor graphite intercalation compound are reported in the temperature range 3 < T < 300 K. In the lowest temperature range the electronic contribution dominates the thermal conductivity, while at higher temperature there is a dominant lattice contribution, which is much smaller than pristine graphite. The thermopower is negative in the whole temperature range.

Magnetic Heat Capacity of Stage 2 Graphite-Coc1 2

The heat capacity C p of graphite-CoC1 2 (stage 2) is measured at zero and high (up to 14 T) magnetic fields (H applied in-plane). By suppressing the magnetic contribution to C p at the highest fields, we are able to decompose C p into its electronic, lattice, and magnetic contributions. The magnetic heat capacity C M is seen to have a broad peak at ⋍ 9.1 K. The shape of this peak is consistent with the reported Monte Carlo calculations of C M based on a twodimensional xy model.

Magnetoreflection and Shubnikov-de Haas Experiments on Graphite Intercalation Compounds

Graphite intercalation compounds represent a class of compounds with many similarities to the superlattice semiclnductors prepared by molecular beam epitaxy. Intercalated graphite has recently attracted considerable attention because the addition of an intercalant can dramatically change the electronic properties of the host graphite material. For example, with the addition of AsF5, an intercalation compound with room temperature conductivity comparable to that of copper can be achieved [1], while the addition of an alkali metal can result in a superconductor [2]. Similar to the behavior in modulation-doped superlattices, high conductivity in intercalated graphite is achieved by a charge transfer from the intercalate layer, where the mobility is low, to the high mobility graphite layers.