High-quality YBa2Cu3O7/insulator/LaNiO3 trilayers obtained by pulsed laser deposition

YBa2Cu3O7/Insulator/LaNiO3 (YBCO/I/LNO) epitaxial trilayers were produced by pulsed laser deposition on LaAlO3(1 0 0) and SrTiO3(1 0 0) substrates. The processing conditions of the three films were optimised in order to obtain a high-quality epitaxy and to ensure that the surface of the two bottom layers had very low roughness and a low number of droplets. The use of SrTiO3 and CeO2 as insulating materials was investigated. All the deposited films were single oriented and epitaxial, with 0.1-0.8degrees wide rocking curves, depending on the material. The surface of the LNO and the insulator layers was flat, with roughness 1-2 nm, and with a low droplet density (10(5) cm(-2)). The LNO layer had a low electrical resistivity of a few hundred of muOmega cm, whereas the top YBCO layers presented good superconducting properties (critical temperature close to 85 K and a critical current density of 10(6) A/cm(2) at a temperature near to 77 K). (C) 2002 Elsevier Science Ltd. All rights reserved.