Relation of sample stoichiometry and growth conditions in SrCoO$_{3−\delta}$ thin films

Strontium cobaltite (SrCoO$_{3-\delta}$) exists in two topotactic phases, depending on the oxygen content. SrCoO$_3$ is a ferromagnetic metal (T$_C$ =305K) with perovskite structure while SrCoO$_{2.5}$ is an antiferromagnetic insulator (T$_N$ =570K) with brownmillerite tructure [1]. We aim at growing thin films of SrCoO$_{3−\delta}$ via molecular beam epitaxy, and thus investigate the influence of growth conditions like the elemental deposition rate of Sr and Co, substrate temperature and oxygen pressure on the sample toichiometry and surface topography. For this, we employ in-situ electron diffraction to monitor the sample growth and ex-situ X-ray reflectometry and atomic force microscopy to investigate the structural properties. The stoichiometry is determined by Rutherford backscattering spectrometry. We provide a comprehensive overview of the samples addressing the requirements to achieve a Sr:Co stoichiometry of 1:1. [1]C.K. Xie et al., Appl. Phys. Lett 99, 052503 (2011