Magnetic properties of artificially prepared ordered two-dimensional shunted and unshunted Nb-AlO_x-Nb Josephson Junction Arrays

In this Chapter, we present our latest experimental results (along with their theoretical interpretation) related to some unusual magnetic properties of artificially prepared ordered two-dimensional Josephson junction arrays (of both shunted and unshunted Nb-AlO_x-Nb tunnel junctions). Namely, we address the following topics: (i) influence of non-uniform critical current density profile on magnetic field behavior of AC susceptibility, (ii) origin of the so-called dynamic reentrance phenomenon, and (iii) manifestation of novel geometric quantization effects in temperature behavior of AC magnetic response.