Combinatorial solid state chemistry by multitarget laser ablation: a way for the elaboration of new superconducting cuprates thin films?

Laser ablation by varying the number of consecutive laser pulses upon two t argets, one superconducting YBa2Cu3O7, the other insulating MCuO2 (M = Sr, Ca), is used to build thin films of tuneable average compositions. Most of the samples are found to display high-T-c superconductivity with critical t emperature generally higher than the 60 K of the 'Cava phase', the prototyp ic structure with two consecutive conducting CuO2 planes and containing sam e types of atoms. The properties of the samples are not linearly dependent on the concentration of species coming from the insulating target. In addit ion, they depend not only on the ratio of the number of pulses on each targ et, but also on the number of consecutive pulses on each target. Thin films are characterized by temperature-dependent DC conductivity, X-ray diffract ion, Castaing microprobe and infrared reflectivity spectroscopy. Present re sults suggest the robustness of high-T-c superconductivity, possibly relate d to a 'Cava-phase-like' skeleton. (C) 1999 Elsevier Science S.A. All right s reserved.