Dissipative state of superconducting zinc whiskers

The current-induced breakdown of superconductivity in Zn and Zn-Ag alloy whiskers close to the critical temperature has been investigated. Above the critical current I_c the superconductor enters a dissipative state with characteristics showing a regular voltage step structure due to the appearance of phase-slip centers. For short samples there is an influence of the superconducting contacts. Unaffected phase-slip centers are only observed in long samples. For this case the temperature-independent quasiparticle relaxation time is found to be 3.2 × 10^–8 sec. For the zero-voltage intercept I₀ a value of 0.56 I_c is obtained.