NEGATIVE MAGNETORESISTANCE IN PREGRAPHITIC CARBONS

A theory of the negative magnetoresistance of disordered carbons is presented. The model, based on earlier work by Yazawa, is capable of a good quantitative fit to experimental results on a wide range of materials as a function of magnetic field and temperature. The negative magnetoresistance is seen to result from the field dependence of the carrier concentration as a consequence of the two-dimensional character of these disordered materials. The parameters of the theory are related to the structure of the materials and provide information about the evolution of the structure as the materials are graphitized. © 1979.