Second magnetization peak in flux lattices: The decoupling scenario

The second peak phenomenon of flux lattices in layered superconductors is described in terms of a disorder induced layer decoupling transition. For weak disorder the tilt modulus undergoes an apparent discontinuity which leads to an enhanced critical current and reduced domain size in the decoupled phase. The Josephson plasma frequency is reduced by decoupling and by Josephson glass pinning; in the liquid phase it varies as 1/[BT(T+T₀)], where T is temperature, B is field, and T₀ is the disorder dependent temperature of the multicritical point.