Control of the colossal magnetoresistance by strain effect in Nd0.5Ca0.5MnO3 thin films

Thin films of Nd0.5Ca0.5MnO3 manganites with colossal magnetoresistance (CM R) properties have been synthesized by the pulsed-laser deposition techniqu e on (100)-(SrTiO3). The lattice parameters of these manganites and correla tively their CMR properties can be controlled by the substrate temperature T-S. The maximum CMR effect at 50 K, calculated as the ratio rho (H=0T)/rho (H=7T) is 10(11) for a deposition temperature of T-S=680 degreesC. Structu ral studies show that the Nd0.5Ca0.5MnO3 film is single phase, [010]-orient ed and has a pseudocubic symmetry of the perovskite subcell with a=3.77 Ang strom at room temperature. We suggest that correlation between lattice para meters, CMR, and substrate temperature T-S result mainly from substrate-ind uced strains which can weaken the charge-ordered state at low temperature. (C) 2001 American Institute of Physics.