Extrinsic magneto resistance in La2/3Ca1/3MnO3 thick films

Thick films of La0.66Ca0.33MnO3 have been obtained on alumina substrate by the "paint-on" method. They exhibit a clear extrinsic magneto resistance (b road metal-insulator transition with peak temperature lower than Curie temp erature, magneto resistance at low temperatures and magnetic fields. etc.). This behavior seems to be related to the competition between tunneling mag netoresistance (TMR) at the grain boundaries and double exchange in the gra ins. An anomaly is observed in the resistance vs. applied magnetic field at low temperatures. which support the presence of TMR. EDAX analysis perform ed to the films shows elemental composition deviations near to the grain bo undaries. (C) 2001 Published by Elsevier Science B.V.