Metal-insulator transition and nonlinear conductivity in Mn-deficient (LaCa)MnO3

We report on linear and nonlinear electronic transport in the La0.65+3vCa0.35-3vMn1-vO3 system (0 ≤ v ≤ 0.06), that exhibits a disorder driven metal-insulator (M-I) transition. This transition is compared with the compositionally induced M-I transition in the La1−xCaxMnO3 system (0.17 ≤ x ≤ 0.22). Nonlinear conductivity of electronic origin, as measured using short, single current pulses, was detected only in the disordered non-metallic samples (v = 0.04−0.06), in electric fields E ≲500 V/cm. At low temperatures and high electric fields, the I-V characteristics exhibit power-law behavior. Conductivities two orders of magnitude higher than ohmic were obtained for v = 0.04.