NUMERICAL SIMULATIONS ON 2-DIMENSIONAL VORTEX LATTICES

We have studied the dynamics of a two-dimensional vortex lattice with the use of a molecular dynamics method for systems of up to 2000 vortices. The interaction potential is taken to be of the Pearl form and temperature is taken into account via a white Gaussian noise source. We find that the low temperature state is predominantly a triangular array of two-dimensional vortices. Long range order is absent. Defects are present at very low temperatures already, and possibly cause at higher temperatures Kosterlitz-Thouless (dislocation mediated) melting of the lattice. With a London penetration depth of 1250 angstrom, we calculate the field distribution at zero temperature and the T-dependent magnetic field time-correlation function. The results compare well with NMR experiments on Tl in Tl2Ba2CaCu2O8 in the temperature range below the melting temperature T(m).