QUANTUM INTERFERENCE AND CONFINEMENT PHENOMENA IN MESOSCOPIC SUPERCONDUCTING SYSTEMS

The superconducting field (H)-temperature (T) phase boundary has been measured in mesoscopic Al samples of different topology: lines, open and filld squares, which were made under the same conditions from the same material. These samples clearly show different superconducting H-T phase boundaries which are nicely reproducing the predictions of the theoretical calculations made for their particular confinement geometries. The confinement of the flux lines by the lattice of the submicrometer holes has been studied in the Pb/Ge multilayers. A substantial enhancement of the critical current j(c), has been achieved. Sharp integer and rational matching peaks in the j(c)(H) curve are observed. The possibility of the ''quantum design'' of the superconducting critical parameters (H-c(T) and j(c)(T, H)) of the mesoscopic and nanostructured superconductors by optimizing the confinement geometry for the superconducting condensate and for the flux lines has been demonstrated.