A crossover from Mott to Efros–Shklovskii hopping conduction In insulating Al70Pd22.5Re7.5 quasicrystals – a magnetoresistance study

Abstract Combining the conductivity and the magnetoresistance (MR) data with MR theories, we found that there is a crossover from the Mott to Efros–Shklovskii variable-range hopping conduction in insulating Al70Pd22.5Re7.5 quasicrystals (QCs) with the resistivity ratio R =ρ(4.2 K )/ρ(300 K ) equal to 118 and 81. The crossover temperature is seen to decrease with decreasing R value. At low temperature the rapid decrease in the magnitude of the negative MR in highly resistive QCs might be correlated with the conduction via the states in the Coulomb gap as observed in CdTe semiconductors.