Raman spectroscopy of La2NiMnO6 films on SrTiO3 (1 0 0) and LaAlO3 (1 0 0) substrates: Observation of epitaxial strain

La2NiMnO6 is a multiferroic material of interest due to its unique dielectric and electrical resistance properties under an applied magnetic field. Raman spectroscopy was used to monitor the quality of La2NiMnO6 films grown on LaAlO3 (1 0 0) and SrTiO3 (1 0 0) substrates. The films have strikingly different properties at the film–substrate interface owing to the relative quality of heteroepitaxial growth. The films grown on SrTiO6 (1 0 0) did not have any biaxial strain, because of strong epitaxial match to the substrate. The films grown on LaAlO6 (1 0 0), however, showed large shifts in the Ag and Bg phonon modes due to biaxial strain. This was observed in both depth profile experiments in 200 nm films using confocal microscopy and in thinner films (down to 10 nm) grown on the substrates.