Magnetic properties of strip-like Josephson-junction arrays

Zero-field-cooled (ZFC) and field-cooled (FC) magnetic properties of strip- like Josephson-junction (JJ) arrays with very strong demagnetizing effects are calculated from basic laws. Similar to slab-like JJ arrays without cons idering demagnetizing effects, a vortex state evolves to a critical state ( CS) with increasing maximum JJ currents in the ZFC case, and a vortex state always remains with a negative low-field susceptibility in the FC case. Ho wever, the strong demagnetizing effects cause qualitative changes in the CS , where the overall feature of the field and current profiles turns out to be similar to that in type-II superconducting strips, but not like the ordi nary Bean CS in slab-like JJ arrays, the CS current profile is never flat a nd the critical current is no longer a step function of the maximum JJ curr ent as in slab-like JJ arrays. The calculated results of different types of JJ arrays indicate that although the intergranular CS in granular supercon ductors may have a common origin, the discovered paramagnetic Meissner effe ct in them is still difficult to explain.