ELECTRICAL-TRANSPORT PROPERTIES OF ARTIFICIALLY LAYERED FILMS OF [BACUO2](2) [(SR,CA)CUO2](N)/

In this letter we show that SrCuO2/BaCuO2 and CaCuO2/BaCuO2 based arti ficial structures of very good crystallographic quality can be grown b y pulsed laser deposition. We demonstrate that the most important para meters which determine the superconductive properties are the chemical composition, the oxygen growth pressure, and the CO2 contamination. A major difference is found in the behavior of resistivity between film s containing Sr and Ca, respectively. Namely [BaCuO2](2)/[SrCuO2](n) f ilms never show any trace of superconductivity, while [BaCuO2](2)/[CnC uO(2)](n) films result in having, for growth oxygen pressures P-o2> 0. 2 mbar, a full transition with T-c (zero resistance) up to 46 K. Furth ermore we demonstrate that even a tiny amount of CO2 in the oxygen gro wth atmosphere can suppress completely the superconducting properties of these artificial structures. (C) 1997 American Institute of Physics .