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 lD/ξ, where lD is the Debye screening length and ξ is the coherence length, and can be neglected in conventional superconductors with lDξ. However, in high-temperature superconductors, where lD/ξ∼1, the effect is very pronounced and could be used for improvement of the transport critical current.