Vortex lattice depinning vs. vortex lattice melting: a pinning-based explanation of the equilibrium magnetization jump

In this communication we argue that the Vortex Lattice Melting scenario fails to explain several key experimental results published in the literature. From a careful analysis of these results we conclude that the Flux Line Lattice (FLL) does not melt along a material- and sample-dependent boundary Hj(T) but the opposite, it decouples from the superconducting matrix becoming more ordered. When the FLL depinning is sharp, the difference between the equilibrium magnetization Meq(T,H) of the pinned and unpinned FLL leads to the observed step-like change Meq(T,H). We demonstrate that the experimentally obtained ΔMeq(T,H) can be well accounted for by a variation of the pinning efficiency of vortices along the Hj(T) boundary.