Monte Carlo calculation of longitudinal and transverse resistivities in a model type-II superconductor

We study the effect of a transport current on the vortex-line lattice in isotropic type-II superconductors in the presence of strong thermal fluctuations by means of driven-diffusion Monte Carlo simulations of a discretized London theory with finite magnetic penetration depth. We calculate the current-voltage (I-V) characteristics for various temperatures, for transverse as well as longitudinal currents I. From these characteristics, we estimate the linear resistivities R{sub xx}=R{sub yy} and R{sub zz} and compare these with equilibrium results for the vortex-lattice structure factor and the helicity moduli. From this comparison a consistent picture arises, in which the melting of the flux-line lattice occurs in two stages for the system size considered. In the first stage of the melting, at a temperature T{sub m}, the structure factor drops to zero and R{sub xx} becomes finite. For a higher temperature T{sub z}, the second stage takes place, in which the longitudinal superconducting coherence is lost, and R{sub zz} becomes finite as well. We compare our results with related recent numerical work and experiments on cuprate superconductors. {copyright} {ital 1997} {ital The American Physical Society}