I. The Hall effect in ordered and disordered systems

Abstract

Deviations from the normal behaviour of the Hall effect may occur when the conventional band theory of solids is inapplicable. Such cases include narrowband semiconduction (bandwidths ≤kT), few- or multiphonon-assisted hopping transport among localized states, and extended state motion with short mean free path. In the hopping case, a general quantum mechanical argument is presented which shows the physical origin of the Hall effect. The question of the sign of the Hall effect is very briefly reviewed. We also present a short review of recent calculations of the Hall effect for disordered systems, taking into account the randomness in the site positions. Finally, comparison is made between experiment and the theoretical predictions.