Decoupling transition of flux lattices in pure layered superconductors

We study the decoupling transition of flux lattices in layered superconductors at which the Josephson coupling J is renormalized to zero. We identify the order parameter and related correlations; the latter are shown to decay as a power law in the decoupled phase. Within the second-order renormalization group we find that the transition is always continuous, in contrast with results of the self-consistent harmonic approximation. The critical temperature for weak J is ∼1/B, where B is the magnetic field, while for strong J it is ∼1/B and is strongly enhanced. We show that renormaliztion group can be used to evaluate the Josephson plasma frequency and find that for weak J it is ∼1/B T2 in the decoupled phase.