THE MAGNETORESISTANCE OF CARBON-BLACK SAMPLES AT DIFFERENT TEMPERATURES

We present experimental results for the magnetoresistance of carbon-black, in magnetic fields (B) up to 15 T, and its temperature dependence at temperatures (T) from 10 K to 1.2 K. At these temperatures the electrical conduction is given by variable range hopping with Coulomb gap. The results show a B2 dependence at low fields and a B1/2 dependence in the limits of high fields. We show that the model of hydrogenlike localized states cannot explain the experimental results.