Numerical study of random superconductors

The XY model with quenched random disorder is studied numerically at T=0 by a defect scaling method as a model of a disordered superconductor. In 3D we find that, in the absence of screening, a vortex glass phase exists at low T for large disorder in 3D with stiffness exponent ¿˜+0.31 and with finite screening and in 2D this phase does not exist. For weak disorder, a superconducting phase exists which we identify as a Bragg glass. In the presence of screened vortex–vortex interactions, the vortex glass does not exist but the Bragg glass does.