Epitaxial (La,Sr)TiO3 as a conductive buffer for high temperature superconducting coated conductors

The transport and structural properties of (La,Sr)TiO3 epitaxial thin films grown by pulsed-laser deposition is presented. In particular, the potential use of (La,Sr)TiO3 as a conductive buffer layer for subsequent growth of high temperature superconducting films for coated conductors is discussed. Van der Pauw measurements of film resistivity as a function oxidation conditions show that, for undoped LaTiO3 films, the resistivity increases rapidly as background oxygen pressure is increased, which is consistent with the formation of the LaTiO3+x phase. Sr doping of LaTiO3 significantly enhances the conductivity of thin film materials when synthesized under oxidizing conditions. The transport behavior for Sr-doped LaTiO3 films correlates with structural data showing no significant shift in lattice spacing as oxygen partial pressure is increased during film growth. In addition, the epitaxial growth of (La,Sr)TiO3 on biaxially textured Ni alloy tapes is demonstrated. These results suggest that (La,Sr)TiO3 is a viable candidate as a conducting buffer for superconducting film growth on biaxially textured metal tapes.