Characterization of Resistive Hotspots induced in Superconducting NbTi thin film by an electrical current pulse

Abstract

We report on the creation of resistive states in NbTi superconducting filament on polished crystalline Al2O3 using the 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 hotspot and phase slip center. A time dependent voltage response exposes the collapse of superconductivity that occurs after a certain delay time td. We found that hotspots occur at temperatures much lower than the transition temperature. This can be clearly seen in a current versus temperature diagram. The thermal cooling and heat escape times were extracted from fitting the experimental data of the delay time to Tinkham’s amended version of the Time-Dependent Ginzburg-Landau (TDGL). The temperatures reached at the core of hotspots were determined without any parameter adjustment.