Monte Carlo data and duality arguments, applied to a lattice model, are presented which indicate that a three-dimensional type-II superconductor should have a transition asymptotically equivalent to that of a superfluid with reversed temperature axis, and not a first-order transition. Results may apply to the nematic—smectic-$A$ transition.

• Received 18 September 1981

DOI:https://doi.org/10.1103/PhysRevLett.47.1556