Melting of the charge-ordered state under substantially lower magnetic field in structurally improved Pr1−xCaxMnO3 (x=0.3−0.5) thin films

We report melting of the charge-ordered state in low bandwidth manganite PCMO (x=0.3-0.5) thin films under substantially lower magnetic field. Two different in situ post-deposition annealing conditions were applied on the PCMO thin films grown by pulsed laser deposition at a deposition temperature of 500 °C, which is significantly lower compared to the traditional deposition temperature for complex oxides. Thorough structural and magnetic characterization of these two films show improved crystalline and magnetic properties in PCMO thin films annealed at a lower temperature that leads to stronger ferromagnetic interaction at the cost of charge- and orbital-ordered states. In these structurally improved film a larger irreversible metamagnetic transition can be observed and the onset magnetic field required to melt the charge-ordered state reduces to only around 2 T at 70 K temperature in the sample with x=0.4 and nearly around 2.5 T for x=0.5. Additionally, the in situ post-deposition annealing at 500 °C decreases the insulator-metal transition about 2.5 T when compared to the samples annealed at 700 °C. Therefore, a larger colossal magnetoresistance effect is observed under a moderate value of applied magnetic field in these PCMO films with better crystalline order. This result is of extreme importance for the future generation of oxide electronics using phase-change property of strongly correlated materials.