EXPERIMENTS USING HIGH-T_C VERSUS LOW-T_C JOSEPHSON CONTACTS

摘要

Remarkably rich physics is involved in the behavior of hybrid Josephson junctions, connecting high-T_c and low-T_c superconductors. This relates in particular to the different order parameter symmetries underlying the formation of the superconducting states in these materials. Experiments on high-T_c/low-T_c contacts have also played a crucial role in settling the decade-long d-wave versus s-wave debate in cuprate superconductors. Recently, such hybrid junctions have enabled more detailed pairing symmetry tests. Furthermore, with these junctions, complex arrays of π-rings have been realized, enabling studies on spontaneously generated fractional flux quanta and their mutual interactions. Steps toward novel superconducting electronic devices are taken, utilizing the phase-shifts inherent to the d-wave superconducting order parameter. This paper is intended to reflect the current status of experiments using high-T_c and low-T_c Josephson contacts.