Effects of oxygen content on the structural and transport properties in epitaxial Nd0.7Sr0.3MnO3−xNd0.7Sr0.3MnO3−x thin films

Epitaxial Nd0.7Sr0.3MnO3−x (NSMO) thin films, 120 nm thickness, were grown coherently on the (0 0 1) (LaAlO3)0.3 (Sr2AlTaO6)0.7 (LSAT) substrates by using pulsed-laser deposition (PLD). Effects of oxygen contents controlled by post-annealing in vacuum on the structural and transport properties of the NSMO films were carefully studied by x-ray reciprocal space maps (RSMs) and resistivity measurements. It is clearly shown that both the out-of-plane lattice parameters of the films and the transition temperatures Tp (peak resistance) can simultaneously change as the oxygen contents, the in-plane lattice coherency is maintained consistently with that of the LSAT substrate at the same time. The larger altered transport properties are chiefly ascribed to the increase of Mn3+ ions and the distortion of MnO6 octahedra in films. The oxygen compositions are deduced from the out-of-plane lattice parameters of coherency epitaxy NSMO films. The Kröger–Vink notation was used for explaining the correlation of oxygen vacancy and transport properties.