Surface superconductivity and capacitance of superconductors under electric and magnetic fields

A superconducting layer exposed to a perpendicular electric and parallel magnetic field is considered within the Ginzburg-Landau (GL) approach. The GL equation is solved near the surface and the surface energy is calculated. The nucleation critical field is shown to be changed in dependence on the magnetic and electric field. Special consideration is payed to the induced magnetic-field effect caused by diamagnetic surface currents. The latter effect constitutes the main contribution to the effective inverse capacitance which determines the effective penetration depth.
The surface energy becomes strongly dependent on the width of the sample.
An experimental realization is suggested for determining the change in the effective capacitance of the layer.