New artificial superlattices: correlation between structural disorder and transport properties

The development of thin film deposition techniques allowed the growth of new artificial materials leading to the discovery of new high T/sub c/ superconducting compounds as infinite layer based superlattices [(BaCuO/sub 2/)/sub m//(CaCuO/sub 2/)/sub n/]. The order of the superlattice structure seems to be one of the crucial parameters to be improved so as to induce a superconductivity onset in these materials and to make them suitable for technological applications. In this paper we present a study on the correlation between structural disorder and transport properties of several artificial superlattices grown by pulsed laser ablation technique. Our goal was to simulate the layered structure of copper oxide superconductors, so as to create new artificial superconducting materials and study the charge transfer mechanism. We chose infinite layer phases (SrCuO/sub 2/, CaCuO/sub 2/, BaCuO/sub 3/) for the blocks containing CuO/sub 2/ planes and doped infinite layer phases (CaCu/sub 1-x/Sc/sub x/O/sub y/, SrCu/sub 1-x/Sc/sub x/O/sub y/, CaCu/sub 1-x/Ag/sub x/O/sub y/ and SrCu/sub 1-x/Ag/sub x/O/sub y/, with x ranging from 0.1 to 0.2) for the charge reservoir blocks. By means of reflection high energy electron diffraction (RHEED) and X-ray structural characterization as well as resistivity and Hall effect measurements, we perform a comparative analysis of structural and transport properties of these samples and we tried to explain them in terms of Anderson's theory of disorder.