LANGEVIN SIMULATIONS OF 2-DIMENSIONAL VORTEX FLUCTUATIONS - ANOMALOUSDYNAMICS AND IV-EXPONENT

The dynamics of two-dimensional (2D) vortex fluctuations is investigat ed through simulations of the 2D Coulomb gas model in which vortices a re represented by soft disks with logarithmic interactions. The simula tions strongly support a recent suggestion that 2D vortex fluctuations obey an intrinsic anomalous dynamics manifested in a long-range 1/t t ail in the vortex correlations. A nonlinear IV exponent a, which is di fferent from the commonly used Ambegaokar-Halperin-Nelson-Siggia expon ent a(AHNS) and is given by a = 2a(AHNS)-3, is confirmed by the simula tions. The results are discussed in the context of earlier simulations , experiments, and a phenomenological description.