INCREASE OF THE CRITICAL-CURRENT BY AN EXTERNAL ELECTRIC-FIELD IN HIGH-TEMPERATURE SUPERCONDUCTORS

An electric field directed perpendicular to the surface of a superconductor changes the superconducting properties near the surface and creates an additional barrier for flux penetration into the sample. This effect is characterized by the value l(D)/xi, Where l(D) is the Debye screening length and xi is the coherence length, and can be neglected in conventional superconductors with l(D) much less than xi. However, in high-temperature superconductors, where l(D)/xi approximately 1, the effect is very pronounced and could be used for improvement of the transport critical current.