Two-dimensional array of diffusive SNS junctions with high-transparent interfaces - art. no. 180503

We report a comparative study of the properties of two-dimensional arrays a nd single superconducting-film-normal-wire-superconducting-film (SNS) junct ions. Superconducting and normal metal parts are made from the same materia l (superconducting polycrystalline PtSi film), ensuring that the NS interfa ces of our SNS junctions are highly transparent. We have found the two-dime nsional arrays to reveal some unusual features: (i) the significant narrowi ng of the zero bias anomaly in comparison with single SNS junctions, (ii) t he strengthening of subharmonic energy gap structure, with up n = 16 (eV= /-2 Delta /n). with some numbers being lost, (iii) the transition from two- dimensional logarithmic weak localization to metallic behavior. Presented r esults show that coherent phenomena governed by Andreev reflection are not self-averaging and are maintained over a macroscopic scale.