Multilayer high-temperature superconductors

Using the BCS approach and a tightbinding description of the band structure, we explore some superconducting properties of layered superconductors. Particular emphasis is devoted to the interlayer pairing interaction g3. Negative values of g3 lead to a staggered order parameter, having alternating signs from layer to layer, while g3 positive leads to one sign only. Adopting a superconducting loop, interrupted by a multilayer, it is shown that the sign of g3 can be determined experimentally. The same holds for a DC SQUID configuration, consisting of two multilayer Josephson junctions in a loop, and for an AC SQUID. © 1993.