Tuning the Resistive Switching of Superconducting Films by Geometry Effects

In a superconductingphoton detector, the effective transition to the normal state can be induced by the instability of the flux flow regime. Indeed, in the presence of self-magnetic field, the local suppression of superconductivityinduced by photon absorption determines vortex nucleation and flux flow regime, which can make the superconductingstate unstable. Understanding such instability can boost the performances of those superconductingdevices based on this resistive switching. Here, we present the study of the geometry influence on such instability in NbN and NbTiN ultrathin films. Despite the same patterned microbridge geometry, the two superconductors show different behaviors at very low applied magnetic fields. A comparison with other superconductors outlines the possibility to tune the resistive switching by geometry effects in interesting materials for devices applications. Finally, we also report the influence of the cooling environment on the electric critical power in superconductingthin films.