Masking effect of heat dissipation on the current-voltage characteristics of a mesoscopic superconducting square with leads

A theoretical analysis based on a numerical solution of the coupled time-dependent Ginzburg-Landau and heat dissipation equations shows a strong dependence of the critical currents on the applied magnetic field in a mesoscopic square with attached contacts. In agreement with experiment we found hysteresis which are caused by a strong heat dissipation in the sample at currents close to the depairing Ginzburg-Landau current and/or the dynamics of the superconducting condensate. The theoretically obtained nonmonotonous dependence of the switching current (from superconducting to the resistive state) on the applied magnetic field, arising from the changes in the vorticity, agrees quantitatively with the experimental data. Our results show that heat dissipation leads to an increase of the hysteresis in the current-voltage characteristic and hence masks the actual dynamics of the superconducting condensate.