EFFECTIVE-MEDIUM THEORY FOR HOPPING TRANSPORT IN A MAGNETIC-FIELD

We review results of effective-medium calculations of the Hall conduct ivity and the magnetoconductivity of three-dimensional systems. In the case of the Hall conductivity we focus on the dependence of the stati c Hall mobility oil the critical hopping length, on the appearance of quantum oscillations and on its frequency dependence. We argue that th e investigation of the frequency dependence is a possible way for dete rmining the exponential prefactor of the Hall conductivity. In tile ca se of the magnetoconductivity we concentrate on anisotropic behavior a nd on its dependence on frequency.