The electric and magnetic properties of graphite.

Graphite is perhaps the most unique of all solids. It has long been known that graphite possesses a layer structure. Within a layer the carbon atoms are arranged in a continuous hexagonal array, each atom having three nearest neighbors at a distance of 1.42 A°. The distance between adjacent layers, on the other hand, is 3.3'/ A°. The interaction between the layers is thus very weak, a fact which results in large anisotropies in the properties of graphite. Thus the magnetic susceptibilities parallel and perpendicular to the graphite planes differ by a factor of 40, and the electrical conductivities in these directions differ by a factor of 10^4- 10^5