Phase structure of a lattice superconductor

A lattice Ginzburg-Landau model of superconductivity is explored in a Monte Carlo computer simulation (for charge $e^2=5\mathrm{}$). The superconducting-normal transition is strongly first order deep in the type-I region and becomes more weakly first order moving in the direction of the type-II region. Beyond a certain point, the data suggest a second-order transition. The data are consistent with the existence of a tricritical point separating these two regimes.