Decoupling and melting in a layered superconductor

We report results for a 3D simulation of a layered superconductor. There are two significant temperatures. The first corresponds to melting of the vortex lattice in the a-b plane (T_ab) and the second to decoupling of the layers (T_dc) with T_ab \le T_ dc. The decoupling is found to be a first order transition with an associated entropy of ~0.25-0.4 k_B/pancake. The melting has no obvious thermodynamic signature, and could be a crossover. The width of the intermediate regime T_ab<T<T_dc, decreases with increasing anisotropy such that for the more anisotropic system we cannot distinguish the melting and decoupling temperatures.