Vortex-lattice states at strong magnetic fields

At strong magnetic fields, Landau quantization invalidates the semiclassical approximations which underly the Ginzburg-Landau (GL) theory of the mixed states of type-II superconductors. We have solved the microscopic mean-field equations for the case of a two-dimensional electron system in the strong magnetic-field limit. For delta-function attractive interactions there exist n+1 pairing channels in the nth Landau level. For n>0, two channels share the maximum ${\mathit{T}}_{\mathit{c}}$, and the order parameter differs markedly from expectations based on GL theory.