Density dependence of the rectification of vortex motion in a circular asymmetric channel

We study the rectification of vortex motion in an asymmetric ring channel in a Corbino setup. With an applied ac current, the motion of vortices in the channel is rectified by the asymmetric potential and induces a dc net flow. The net flow in such a system strongly depends on vortex density, and we distinguish "single-vortex" rectification regime (for low density, when each vortex is rectified individually) determined by the potential-energy landscape inside each cell of the channel and "multi-vortex", or "collective", rectification (high density case) when the interaction between vortices becomes important.