JOSEPHSON GLASS AND DECOUPLING OF FLUX LATTICES IN LAYERED SUPERCONDUCTORS

Phase transitions of a flux lattice in layered superconductors with ma gnetic field perpendicular to the layers and in the presence of disord er are studied. We find that the Josephson coupling between layers lea ds to a strongly pinned Josephson glass (JG) phase al low temperatures and fields. The JG phase is bounded by a decoupling transition line a nd a depinning transition line. These lines cross and form a multicrit ical point where four phases meet. The phase diagram accounts for unus ual data on Bi2Sr2CaCu2O8 such as the ''second peak'' transition and t he recently observed depinning transitions.