Tuning the magnetic properties of L a0.67 S r0.33Co O3-δ films by oxygen pressure

In this paper, oxygen-deficient La0.67Sr0.33CoO3 (LSCO) thin films are prepared by adjusting the oxygen pressure during the deposition. As oxygen vacancies are introduced into the LSCO films, the out-of-plane lattices are elongated, as revealed by x-ray diffraction and high-resolution transmission electron microscopy (HRTEM). Modulated bright and dark stripes observed in the HRTEM images of the oxygen-deficient LSCO films are induced by cation ordering and oxygen vacancy ordering, respectively. Magnetic measurements and first-principles calculations show that the oxygen vacancies depress the magnetism of the LSCO films greatly. We also demonstrate that doping Sr into LaCoO3 and removing oxygen from LSCO have a similar effect on the magnetic properties, which is correlated with a derived formula.