Epitaxial bilayer and trilayer heterostructures grown on LaAlO₃and SrTiO₃(001) single crystals by laser ablation

Abstract

High-quality SA and S/I/S epitaxial heterostructures (S = YBaaCusO,, I = %TO3) have been grown in situ on LaA103 and SrTi03(OOl) single crystals, by the single-chamber pulsed laser deposition technique. YBa2Cu30, and SrX03 layers were deposited sequentially, at a substrate temperature Th = 760 OC, and an oxygen pressure p(02) = 300 mTorr. Structural data showed that the Srli03 layer, grown either on a YBCO film or sandwiched by two YBaCuO films, was strained in the (001) plane and exhibited an elongation of the lattice parameter in the [OOl] direction. This behaviour was consistent with the epitaxial growth of the SA and S/WS structures as revealed by the MEED and ECP patterns. Ion milling in conjunction with AES analysis showed that the thicknesses of the interfacial regions were 535 A, and resulted from residual roughness of the substrates. The critical temperature (TJ and critical current density (io) of the multilayers at 77 K, as determined by an inductive AC method, were found to be To = 89.5 and 90.5 K. and jo = 3 and 5 x lo6 A for trilayers and bilayers, respectively.