Strongly Screened Vortex Lattice Model with Disorder

The three dimensional XY model with quenched random disorder is studied in the strong screening limit, λ→ 0, by defect energy scaling at zero temperature. In zero external field we find that there exists a true superconducting phase with a stiffness exponent θ ' +1.0 for weak disorder. For low magnetic field and weak disorder, we identify an ordered Bragg glass phase which is superconducting. For larger disorder or applied field, there is a non superconducting phase with θ ' −1.0. We estimate the critical external field whose value is consistent with experiment.