Experiments on YBa₂Cu₃O₇-Nb Josephson structures

Abstract

Using superconductors with unconventional pairing symmetry, or by employing π-Josephson junctions, π-phase shifts can be incorporated in superconducting loop-structures. As a result of these builtin π-phase shifts, the structures can exhibit remarkable properties, such as Josephson current counterflow and the spontaneous generation of magnetic half-flux quanta. In this extended abstract we will overview our own activities in this field, based on Josephson contacts between high-temperature and low-temperature superconductors.