Damping of the vortex motion in superconducting Mo₃Si and YBa₂Cu₃O_7-δ

Abstract

The damping of the vortex motion in the superconducting mixed state takes place by means of the power dissipation in the vortex core. In order to minimize the influence of flux pinning, we have performed flux flow experiments at high vortex velocities. We compare the temperature-dependent behaviour of the vortex core for a dirty low-Tc material with a high-Tc cuprate. The theoretical background was given by Larkin and Ovchinnikov, which extended the Bardeen-Stephen model taking into account nonequilibrium effects. For the low-Tc superconductor amorphous Mo3Si, we find that the core resistivity ρ̃ is equal to the normal-state value ρn, and only weakly temperature dependent. In the cuprate YBa2Cu3O7-δ ρ̃ decreases with decreasing temperature. The moderately clean limit and possibly node lines in k-space of the order parameter appear to have a strong influence.