In Situ Coherent X-Ray Studies of Complex Oxide Heterostructures

Transition metal oxides possess variable oxygen stoichiometry which can be the cause of distinct changes to physical and electronic properties. One such oxide, strontium cobaltite (SrCoO_x), has two structurally and electrically distinct phases – the insulating orthorhombic brownmillerite (SrCoO_2.5 – BM-SCO) and conducting cubic perovskite (SrCoO_3-δ – PV-SCO) – that reversibly transition via a topotactic pathway with the insertion or removal of oxygen. In the thin film form, this topotactic transition occurs while preserving high quality epitaxial films, making this material system of interest for resistive memory switching applications. Here, BM-SCO based-heterostructures on strontium titanate (STO) and (LaAlO₃)_0.3(Sr₂TaAlO₆)_0.7 (LSAT) (001) substrates are investigated in order to understand changes to the oxide and at different interfaces under oxidizing / reducing conditions and while under applied potential. The results of X-ray diffraction (XRD) and X-ray photon correlation spectroscopy (XPCS) studies will be discussed along with the potential of such materials in the development of improved resistive switching devices in epitaxial heterostructures.