Magnetic signature of symmetry reduction in epitaxial La0.67Sr0.33MnO3 films

The magnetic properties of epitaxially grown La0.67Sr0.33MnO3 perovskite thin films were investigated to elucidate an unexpected broken symmetry between orthogonal [100] and [010] inplane directions, resulting from the magnetostructural coupling between the film and the cubic SrTiO3 (001) substrate. The films were synthesized by molecular beam epitaxy with either complete or zero A-site cation disorder. Magnetization measured in [100] and [010] directions shows differences that signal a reduction of the in-plane cubic symmetry only for T<290 K. The magnetization asymmetry is more robust in the film with complete A-site disorder. These results are attributed to a dominant Mn-3(+) character at the film-substrate interface and an associated out-of-plane bonding character with hypothesized origins in both charge imbalance and strain effects. (C) 2011 American Institute of Physics. [doi:10.1063/1.3623442]