Current induced Non equilibrium states In NbTi superconducting Bridge*

We report on the discrimination between dissipative states in NbTi superconducting filament on polished crystalline Al2O3 using current driven pulse technique. A current pulse larger than the depairing current (Ic) initiates a dissipation in a localized spot. The non-equilibrium state described by the two dissipative mechanism pinpointed as hot spot or phase slip center. A voltage underlines the collapse of the superconductivity show up after a certain delay time td. We found that the hostspot occurs at low temperature, the phase slip center close to the transition temperature, and proved that a hot spot is ignited by a phase slip center. The thermal relaxation time was ratiocinated from fitting the experimental data with the Time-Dependent Ginzburg-Landau (TDGL) theory due to M. Tinkham at low and high tempearture.