Abstract
The magnetic screening in high-Tc granular superconductors in low magnetic field (H < Hc1) is discussed in terms of N-body diamagnetic interactions. This situation is similar to the case of superheated superconducting granular suspensions. Namely, the diamagnetic contact involves the existence, even in very low field, of vortex structures, but with a spatially varying flux line density. This explains the recent results by Gygax et al. of muon spin rotation spectroscopy in La1.85Sr0.15CuO4.