The dynamics of vortices in a type-II superconductor with defects is studied by solving the time-dependent Ginzburg-Landau equations in two and three dimensions. We show that vortex flux tubes are trapped by volume defects up to a critical current density where they begin to jump between pinning sites along static flow channels. We study the dependence of the critical current on the pinning distribution and find for random distributions a maximum critical current equal to 2% of the depairing current at a pinning density 3 times larger than the vortex line density, whereas for a regular triangular pinning array the critical current is greater than 7% of the depairing current when the pinning density matches the vortex line density.

• Received 9 October 2001

DOI:https://doi.org/10.1103/PhysRevB.65.104517