Experimental evidence for electron correlation effects in hopping conduction at low temperatures

Abstract

The low temperature variation of d.o. conductivity of disordered Nb-N alloys shows large deviations from the calssical variable-range hopping relation. This behaviour can be accounted for by a Coulomb interaction, which is operative mainly at low temperatures. Although it is difficult to decide which of the existing models of this effect is the more valid, a In R ∞ T ^−½ relation where R is the resistance and T the temperature, gives the better fit to experimental data in the low temperature range.