Evidence for ɛ 2-conductivity in the magnetoresistance of multivalley semiconductors

Abstract
Experimental studies of the liquid-helium temperature resistivities of Ge:Sb compounds with degrees of compensation Kɛ2 conductivity range, reveal that the resistivity is determined by hopping of carriers activated to the upper Hubbard D band. The experimentally observed positive magnetoresistance, which is exponential in the magnetic field, arises from field-induced changes in the occupancy of the spin subbands by electrons. Evidence for the ɛ2-conductivity mechanism is discussed on the basis of certain features of the magnetoresistance associated with g-factor anisotropy of different valleys, which is therefore specific to multivalley semiconductors.