Extrinsic magnetoresistance in La2/3Ca1/3MnO3 thick films

Abstract Thick films of La 0.66 Ca 0.33 MnO 3 have been obtained on alumina substrate by the “paint-on” method. They exhibit a clear extrinsic magnetoresistance (broad metal–insulator transition with peak temperature lower than Curie temperature, magnetoresistance at low temperatures and magnetic fields, etc.). This behavior seems to be related to the competition between tunneling magnetoresistance (TMR) at the grain boundaries and double exchange in the grains. An anomaly is observed in the resistance vs. applied magnetic field at low temperatures, which support the presence of TMR. EDAX analysis performed to the films shows elemental composition deviations near to the grain boundaries.