Computer simulations of a vortex line motion in type-II superconductors

We study a vortex line motion in type-II superconductors which is driven by vortex line tension, Lorentz force, pinning force and thermal fluctuations. On the basis of the local stochastic differential equation for the vortex motion with no torsion approximation, several computer simulations are performed to investigate the pinning behavior of the vortex line. It is shown that at zero temperature for sufficiently high impurity concentration the vortex line is trapped by random impurities, that is, the collective pinning occurs, and the temperature effect leads to the pinning-depinning transition at a certain temperature. (orig.)