Paramagnetic Meissner effect in multiply-connected superconductors

We have measured a paramagnetic Meissner effect in Nb-Al2O3-Nb Josephson-ju nction arrays using a scanning superconducting quantum interference device microscope. The arrays exhibit diamagnetism for some cooling fields and par amagnetism for other cooling fields. The measured mean magnetization is alw ays small, < Phi (tot) - Phi (ext)> < 0.3<Phi>(0) tin terms of flux per uni t cell of the array, where Phi (0) is the flux quantum), for the range of c ooling fields investigated (- 12 Phi (0) to 12 Phi (0)). We demonstrate tha t a different model of magnetic screening, valid for multiply-connected sup erconductors, reproduces all of the essential features of paramagnetism tha t we observe and that no exotic mechanism, such as d-wave superconductivity , is needed for paramagnetism.