MULTIPLE ANDREEV-REFLECTION IN ASYMMETRIC SUPERCONDUCTING WEAK-LINKS

The present paper is a continuation of [1], where we demonstrated the occurrence of multiple Andreev-reflection (AR) in symmetric Pb/n-InSb/ Pb sandwich junctions. Here we are presenting the results of our inves tigations for the asymmetric configuration Pb/n- InSb/Sn. We discuss t he measured I(V)- and dV/dI(V)-characteristics in comparison with nume rical calculations, which we carried out in a theoretical extension of the OTBK-theory [2, 3] and a formulation given by W.M. van Huffelen e t al. [4]. The main features in the characteristics are the subharmoni c gap structure (SGS) and an excess current, which show interesting de viations from the symmetric situation. These deviations can be underst ood in a simple physical picture.