M. E. Luna¹, C. Ballesteros², M. E. Gómez³, E.M. González¹, J.I. Martín¹, P. Prieto³, M.V. Vélez¹ and J.L. Vincent¹. ¹Depto. de Física de Materiales, CC. Físicas. Universidad Complutense, 28040 Madrid (Spain). ³Depto. Física, Universidad del Valle, A.A. 25360 Cali (Colombia).

a-Axis films and superlattices of 1:2:3 cuprates (Cu-O planes perpendicular to the substrate) have been grown by dc magnetron sputtering on cubic SrTiO₃(100) and tetragonal LaSrAlO₄(100) substrates. The structural characterization is performed by high resolution TEM (HRTEM) and x-ray diffraction 9XRD). HRTEM reveals a complicate microstructure, consisting on microdomains separated by 90º boundaries, when the layers are grown on substrate SrTiO₃. However, this peculiar microstructure is absent when tetragonal LaSrAlO₄ substrates are used. XRD f -scan shows four peaks from both types of microdomain orientation and only two peaks in the case of in-plane aligned samples. Finally, the influence of the induced microstructure on the superconducting properties (T_C, J_C) will be reported.