Low-field phase diagram of layered superconductors: The role of electromagnetic coupling

We determine the position and shape of the melting line in a layered superconductor, emphasizing the importance of electromagnetic interactions in the vortex system. In the limit of vanishing Josephson coupling we obtain a generic reentrant low-field melting line. Finite Josephson coupling pushes the melting line to higher temperatures and fields and a line shape ${\mathit{B}}_{\mathit{m}}$∝(1-T/${\mathit{T}}_{\mathit{c}}$ ${)}^{3/2}$ is found. We construct the low-field phase diagram including melting and decoupling lines and discuss various experiments in the light of our results. © 1996 The American Physical Society.