Nature of the superconducting transition in the presence of a magnetic field

The critical fluctuations in type-II superconductors exhibit certain universal features due to the constraint on the form of the order parameter imposed by the external magnetic field. The critical behavior is represented by an interacting particle system with long-ranged multiple-body forces. The superconducting transition corresponds to the liquid-solid transition in this dense vortex plasma and, in the properly scaled form, is always far from the mean field ${\mathit{H}}_{\mathit{c}2}$(T).