Unified phase diagram for the three-dimensional XY model of a point-disordered type-II superconductor

We carry out extensive Monte Carlo simulations of the three-dimensional uniformly frustrated XY model with uncorrelated randomly perturbed couplings, as a model for the equilibrium behavior of an extreme type-II superconductor with quenched uncorrelated random point vortex pinning, in the presence of a uniform applied magnetic field. We map out the resulting phase diagram as a function of temperature T and pinning strength p for a fixed value of the vortex line density. At low p we find a sharp first-order vortex lattice melting phase boundary separating a vortex lattice from a vortex liquid. As p increases, it appears that this first-order transition smears out over a finite temperature interval due to the effects of the random pinning, in agreement with several recent experiments. At large p we find a second-order transition from vortex liquid to vortex glass.