H.U. Habermeier, T. Haage, and J. Zegenhagen, PI für Festkörperforschung, Heisenberstr. 1 D-70569 STUTTGART.

Recent progress in tailoring periodic step structures in vicinal SrTiO₃ single crystal substrate surfaces enables a systematic study of the interplay of growth mediated defect structures and transport properties in HTS thin films. UHV annealed (001)-oriented SrTiO₃ substrates with a miscut angle up to 10º towards the [ 010 ] direction were characterized by UHV-STM and subsequently Y₁Ba₂Cu₃O_7-x films were deposited and analyzed with the STM. A regular nanoscale step structure on the sub-strate generates an almost periodic surface structure of the film. Planar view as well as cross-sectional TEM analysis reveals an anisotropic defect structure arising from the substrate surface. Transport measurements and magneto-opticanalysis of the flux penetration show an anisotropic enhancement of the critical current, j_c, along the step edges. Quantitatively, j_c (5K) measured along the step edge is determined to 8x10⁷ A/cm², perpendicular to the spteps, j_c is comparable to epitaxially grown c-axis oriented Y₁Ba₂Cu₃O_7-x films. The correlation of growth-induced defect structures and flux-line pinning is discussed.