CRITICAL-CURRENT IN HIGH-TC SUPERCONDUCTORS IN EXTERNAL ELECTRIC-FIELD

An electric field directed perpendicular to the surface of a supercond uctor changes the superconducting properties near the surface and crea tes an additional barrier for flux penetration into the sample. This e ffect is characterized by the value l(D)/xi, where l(D) is the Debye s creening length and xi is the coherence length, and can be neglected i n conventional superconductors with l(D) much less than xi. However, i n high-temperature superconductors, where l(D)/xi approximately 1, the effect is very pronounced and could be used for improvement of the cr itical current.