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

Thin films of Nd0.5Ca0.5MnO3 manganites with colossal magnetoresistance (CMR) properties have been synthesized by the pulsed-laser deposition technique on (100)-(SrTiO3). The lattice parameters of these manganites and correlatively their CMR properties can be controlled by the substrate temperature TS. The maximum CMR effect at 50 K, calculated as the ratio ρ(H=0T)/ρ(H=7T) is 1011 for a deposition temperature of TS=680 °C. Structural studies show that the Nd0.5Ca0.5MnO3 film is single phase, [010]-oriented and has a pseudocubic symmetry of the perovskite subcell with a=3.77 Å at room temperature. We suggest that correlation between lattice parameters, CMR, and substrate temperature TS result mainly from substrate-induced strains which can weaken the charge-ordered state at low temperature