Received 29 April 2004; revised 16 March 2005; published 14 July 2005
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∕BT2 in the decoupled phase.