Vortex charge in type II superconductors

In a type II superconductor the gap variation in the core of a vortex line induces a local charge modulation. Accounting for metallic screening, we determine the effective line charge of individual vortices and calculate the electric field distribution in the half space above a field penetrated superconductor. The resulting field is that of an atomic size dipole d similar to ea(B) (Z) over cap, a(B) = Bohr radius, acting on a force microscope in the pico to femto Newton range.*