Paramagnetic and diamagnetic states in two-dimensional Josephson-junction arrays

摘要

Many experiments on high-temperature superconductors have shown paramagneticbehavior when the sample is field cooled. The paramagnetism was firstattributed to a d-wave order parameter creating pi-junctions in the samples.However, the same effect was later discovered in traditional low-temperaturesuperconductors and conventional Josephson-junction arrays which are s-wave. Bysimulating both conventional and mixed pi/conventional Josephson-junctionarrays we determine that differences exist which may be sufficient to clearlyidentify the presence (or absence) of pi-junctions. In particular thepi-junctions cause a symmetry breaking providing a measurable signature oftheir presence in sample.