Theory of the Motion of Vortices in Superconductors

The theory of the motion of vortex lines in the mixed state of type II superconductors is derived on the basis of a local model that is a generalization of the London theory. It is believed the model simulates reasonably well the behavior of relatively pure superconductors (l>₀), giving a vortex line with a normal core. It is found that if the force on a line is produced by a uniform transport current Jₓ, electric fields generated by the motion drive the current through the core, so that the total current flow is Jₓ+J₀ (r-v₋t), where J₀ (r) is the circulation of a stationary vortex and v₋ is the velocity of the line. In part Jₓ represents superfluid flow and in part normal flow. Expressions derived for the viscosity and flow resistivity are nearly identical with empirical laws of Kim and co-workers. The Hall angle expected in the mixed state is the same as in the normal state for a magnetic field equal to that in the core.