Electric properties of contacts to HTS thin films at current densities J > J{sub c}

Abstract

The role of superconducting film contacts when transporting critical current density was investigated using d.c. and electric short pulses. It was found that both d.c. and pulse current exceeding critical current I c dissipate at the film contacts, i.e. at the metal/superconductor planar interface containing an intermediate layer of degraded superconductor. Current I > I c dissipation at the contacts initiates electric-thermal destruction of the superconducting film cathode. The resulting damage to the film is explained in terms of the formation of a (p/i/n) junction at the normal-metal(n)/mixed-state super-conductor(p) interface containing (i) layer of low electric conductivity.