Disorder-induced topological defects in a elastic medium at zero temperature

The density and correlations of topological defects are investigated numerically in a model of a (Formula presented) elastic medium subject to a periodic quenched random potential. The computed density of defects decreases approximately exponentially with the defect core energy. Comparing the defect-free ground state with the ground state with defects, it is found that the difference is described by stringlike excitations, bounded by defect pairs, which have a fractal dimension of (Formula presented) At zero temperature, the disorder-induced defects screen the interaction of introduced vortex pairs.