Correlation Effects on Variable Range Hopping Conduction and the Magnetoresistance

Abstract

Effects of intra-state correlation on the variable range hopping are investigated in the absence and presence of a magnetic field. In the absence of a magnetic field, Mott's expression for the resistivity, ρ∝exp [ T 0 / T ] 1/4 , still holds in its temperature dependence. However, the prefactor T 0 now depends on two types of localization lengths brought about by the intra-state correlation. Magnetoresistance is found to be positive due to the intra-state correlation. It shows a linear dependence on a magnetic field in lower magnetic fields and saturates above a certain magnetic field.