DAMPING OF THE VORTEX MOTION IN SUPERCONDUCTING MO3SI AND YBA2CU3O7-DELTA

The damping of the vortex motion in the superconducting mixed state ta kes place by means of the power dissipation in the vortex core. In ord er to minimize the influence of flux pinning, we have performed flux f low experiments at high vortex velocities. We compare the temperature- dependent behaviour of the vortex core for a dirty low-T-c material wi th a high-T-c cuprate. The theoretical background was given by Larkin and Ovchinnikov, which extended the Bardeen-Stephen model taking into account nonequilibrium effects. For the low-T, superconductor amorphou s Mo3Si, we find that the core resistivity <(rho)over tilde> is equal to the normal-state value rho(n), and only weakly temperature dependen t. In the cuprate YBa2Cu3O7-delta (rho)over tilde> decreases with decr easing temperature. The moderately clean limit and possibly node lines in (k) under bar-space of the order parameter appear to have a strong influence.