Negative Magneto-Resistance in Pyrolytic Carbons

Abstract

Negative magneto-resistance is observed in poorly graphitized carbons at liquid nitrogen temperature or even higher. This peculiar phenomenon has been studied on pyrolytic graphite, as a model material. It is concluded that the negative magneto-resistance is a quantum phenomenon caused by a change of the carrier concentration induced by the applied magnetic field. The incentive for the change of the carrier concentration, which is unusual in itself, lies in the peculiar energy band structure of this material. Theoretical curves calculated on this conjecture reproduce the experimental results very well.