Superconducting superlattices

By piling up ultra-thin layers of discrete materials, physicists now have a choice method for the study of superconductivity at high temperature. These superlattices are prepared by successive layers of YBaCuO and PrBaCuO deposited by cathode sputtering to study the variation of superconductivity with layer thickness. The transition temperature decreases rapidly when the distance between two layers in creases. Current vortices are created, without a magnetic field, widening the transition temperature. The variation of resistivity near critical temperature in a magnetic field shows that the energy required to displace vortices is increasing with the thickness of the YBaCuO layer, with thin layers anisotropy is high and energy dissipation is important. (author). 17 refs., 6 figs