Oxygen stoichiometry, crystal structure, and magnetism of La0.5Sr0.5CoO3-δ

We have prepared a series of polycrystalline samples La0.5Sr0.5CoO3-delta with 0 < delta less than or equal to 0.21 and characterized their oxygen content, crystal structure, and magnetic properties. While the fully oxygenated samples are good ferromagnets, samples with larger delta values display increasingly broad magnetic transitions. The saturation magnetization at 5 K falls rapidly as delta increases. First-principles electronic structure calculations provide insights into the magnetic behaviour of the fully oxygenated compound, and the manner in which ferromagnetic ordering is affected by increasing oxygen non-stoichiometry.