Superconductor-to-normal phase transition in a vortex glass model: numerical evidence for a new percolation universality class

The three-dimensional strongly screened vortex glass model is studied numerically using methods from combinatorial optimization. We focus on the effect of disorder strength on the ground state and find the existence of a disorder-driven normal-to-superconducting phase transition. The transition turns out to be a geometrical phase transition with percolating vortex loops in the ground state configuration. We determine the critical exponents and provide evidence for a new universality class of correlated percolation. (Some figures in this article are in colour only in the electronic version)