A HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY ON EPITAXIAL INFINITE-LAYER SRCUO2 THIN-FILMS GROWN ON A SRTIO3 (100) SUBSTRATE

The authors investigated defect structures introduced into so-called infinite-layer SrCuO2 thin films sputtered on a SrTiO3 (100) substrate. By means of both cross-sectional and plan-view high-resolution electron microscopy (HREM), it has been revealed that the films were epitaxially grown with their c-axis normal to the substrate surface, and several types of defect structures have been estimated. They were essentially composed of double Sr-O planes that make {100} atomic walls. It is remarkable that such walls tended to arrange as loop-like configurations, and also could produce a different ordered structure, i.e., a Sr2CuO3-like structure in local regions. The authors propose defect structural models in the epitaxial infinite-layer SrCuO2 thin films in detail.