Hall voltage sign reversal in thin superconducting films

A novel approach to the superconducting Hall effect is developed, based on the opposing drift of the thermally excited quasi-particles. These collide quasi-elastically with the hydrodynamics superfluid velocity field circulating for outside the core of a vortex, thereby transferring momentum to the latter. The predicted Hall angle, by BCS theory, is of the order of kBTc divided by the Fermi energy, has sign opposite to that in the normal state because of the backflow, and disappears at low temperature.