Quasiparticle energy relaxation times in NbN/CuNi nanostripes from critical velocity measurements

The dynamic instability of the moving vortex lattice at high driving currents in NbN/CuNi-based and NbN nanostripes designed for optical detection has been studied. By applying the model proposed by Larkin and Ovchinnikov [Zh. Eksp. Teor. Fiz. 68, 1915 (1975)], from the critical velocity v* for the occurrence of the instability, it was possible to estimate the values of the quasiparticle relaxation times ?E. The results show that the NbN/CuNi-based devices are characterized by shorter values of ?E compared to that of NbN.