Magneto- and electro-resistance effects in phase separated Pr _0.55(Ca_0.65S_0.35)_0.45MnO ₃ films

Pr_0.55(Ca_0.65S_0.35)_0.45MnO ₃ films were deposited on (001) (La_0.18Sr _0.82)(Al_0.59Ta_0.41)O₃ substrates using pulse laser deposition technique and annealed in oxygen environment at temperatures ranging from 900 to 1100 °C, respectively. X-ray diffraction data suggested that these epitaxial films show a little relaxation in lattice strain without structural change after post-annealing within this temperature range. The as-deposited film and the film annealed at 900 °C showed only insulating and weak magnetic behaviors, but the film annealed at 950 °C depicted a clear metal-insulator (M-I) transition with a strong ferromagnetic property while increased annealing temperature lead to a slight degradation in both electric and magnetic properties. Interestingly, the slightly degraded films above 950 °C showed larger magnetoresistance and electroresistance than the optimized film at 950 °C. The temperature dependence of resistance for the film annealed at 1000 °C was measured at various magnitudes of dc current, and its peak resistance was found to decrease exponentially with increasing current. From a comparison between magnetoresistance and electroresistance, we found that the resistance was suppressed equally by either the application of a 0.7 T magnetic field or a 6 mA current.