Effects of oxygen content on the structural and transport properties in epitaxial Nd 0.7 Sr 0.3 MnO 3 - X thin films

摘要

Epitaxial Nd _(0.7)Sr _(0.3)MnO _(3-x) (NSMO) thin films, 120 nm thickness, were grown coherently on the (0 0 1) (LaAlO _3) _(0.3) (Sr _2AlTaO _6) _(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 T _p (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 Mn ~(3+) ions and the distortion of MnO _6 octahedra in films. The oxygen compositions are deduced from the out-of-plane lattice parameters of coherency epitaxy NSMO films. The Kr?ger-Vink notation was used for explaining the correlation of oxygen vacancy and transport properties.