Galvanomagnetic properties of La0.7Sr0.3Mn0.9Cu0.1O3

La0.7Sr0.3Mn0.9Cu0.1O3 ceramic samples have been obtained by the conventional method of the solid-phase reaction, and their resistivity ρ has been investigated in a temperature range from 50 to 300 K in magnetic fields B = 0–20 T. Dependences are typical of perovskite manganites with a maximum at Tmax = 140–150 K and an increase in ρ near Tmax with increasing external magnetic field B. It has been established that the behavior of resistivity is caused by the variable range hopping conduction mechanism ρ(T) = ρ0(T)exp[(T0/T)1/4], where ρ0(T) ∼ T25/4. The Mott variable range hopping conduction has been observed below the Curie temperature for La0.7Sr0.3Mn0.9Cu0.1O3 samples (TC ∼ 300 K) in a temperature range from 300 to 200 K. The influence of Cu doping on the properties of La0.7Sr0.3MnO3 samples is apparently caused by an additional distortion introduced into the crystal lattice of the material and by a weakening of the double-exchange mechanism.