Defect-induced charge-order melting in thin films of Pr0.5Ca0.5MnO3

We have investigated the relation between defect structure and charge order melting in thin films of epitaxial Pr0.5Ca0.5MnO3 (PCMO), grown under strain on SrTiO3. We compared the behavior of an 80 nm film grown in one deposition step at 840 degrees C with the behavior of a film grown in two steps. In the two-step case, a thin PCMO layer of 10 nm was deposited at 120 degrees C, followed by 70 nm deposited at 840 degrees C. The increase of the growth temperature leads to complete crystallization of the first layer and the lattice constants of the two-step grown film indicate that tensile strain is still present. On the other hand, a magnetic field of only 5 T is required to melt the charge-order state in the two-step grown film, which is a much lower than the value for the normally grown film. This appears to be connected to a larger amount of threading dislocations present in the first (recrystallized) layer. (c) 2007 American Institute of Physics.