COMPLEX LOW-TEMPERATURE TRANSPORT BEHAVIOR OF RNIO3-TYPE COMPOUNDS

The temperature-dependent electrical resistance behaviour of PrNiO3, N dNiO3, Nd0.99Sr0.01NiO3 and Sm0.55Nd0.45NiO3 in zero field as well as in the presence of a magnetic field (H) is reported. The application o f H up to 70 kOe does not influence the so-called metal-insulator tran sition in any of these compounds significantly. Interestingly, the mag nitude of the magnetoresistance, Delta p/p = {p(H)-p(0)}/p(0), in the vicinity of 35 K is significantly larger than that noted below 10 K. i t appears that there are sign crossovers in the magnetoresistance as t he temperature is varied below the transition temperature in most of t hese compounds. The present results suggest that the physics below the transition temperature is quite complex.