VORTEX-GLASS TRANSITION IN 3 DIMENSIONS

We investigate the possibility of a vortex-glass transition in a disordered type-II superconductor in a magnetic field in three dimensions by numerical studies of a simplified model. Monte Carlo simulations at finite temperature and domain-wall renormalization-group calculations at T = 0 indicate that d = 3 is just above the lower critical dimension d(l), though the possibility that d(l) = 3 cannot be definitely ruled out. A comparison is made with XY and Ising spin glasses. The (effective) correlation-length exponent v and dynamical exponent z are in fairly good agreement with experiment.