Substrate-induced strain effects on Pr0.6Ca0.4MnO3 films

We report the characterization of the crystal structure, low-temperature charge and orbital ordering, transport and magnetization of Pr0.6Ca0.4MnO3 films grown on LaAlO3, NdGaO3 and SrTiO3 substrates, which provide compressive (LaAlO3) and tensile (NdGaO3 and SrTiO3) strain. The films are observed to exhibit different crystallographic symmetries from the bulk material and the low-temperature ordering is found to be more robust under compressive-as opposed to tensile-strain. In fact, bulk-like charge and orbital ordering is not observed in the film grown on NdGaO3, which is the substrate that provides the least amount of measured, but tensile, strain. This result suggests the importance of the role played by the Mn-O-Mn bond angles in the formation of charge and orbital ordering at low temperatures. Finally, in the film grown on LaAlO3, a connection between the lattice distortion associated with orbital ordering and the magnetization is reported.