Evidence of orbital reconstruction at interfaces in ultrathin La0.67Sr0.33MnO3 films

Linear dichroism (LD) in x-ray absorption, diffraction, transport, and magnetization measurements on thin La0.7Sr0.3MnO3 films grown on different substrates, allow identification of a peculiar interface effect, related just to the presence of the interface. We report the LD signature of preferential 3d -e(g) (3z(2) - r(2)) occupation at the interface, suppressing the double exchange mechanism. This surface orbital reconstruction is opposite to that favored by residual strain and is independent of dipolar fields, the chemical nature of the substrate and the presence of capping layers.