Relation between microstructure and superconducting properties in a-axis 123 films and superlattices

a-Axis-oriented superconducting EuBa2Cu3O7 films and EuBa2Cu3O7/PrBa2Cu3O7 superlattices have been grown by sputtering on SrTiO3 (100) substrates. Str uctural analysis by high resolution transmission electron microscopy and X- ray diffraction has been performed. Both kind of samples are well-oriented with the c-axis parallel to the substrate plane, the structure at the bound aries is highly coherent and, in the superlattices, high angle X-ray satell ite peaks are observed. The presence of PrBa2Cu3O7 layers in the superlatti ces induces a reduction in the superconducting transition temperature that can be attributed to a charge redistribution process in the CuO2 planes, wh ich in this a-axis orientation belong simultaneously to insulating and supe rconducting layers. (C) 2000 Elsevier Science S.A. All rights reserved.