Characterization of quasiparticle relaxation times in microstrips of NbReN for perspective applications for superconducting single-photon detectors

The study of the flux-flow instability in superconducting materials has recently gained renewed attention due to its potential implications for the use of the analyzed materials as micrometer-sized superconducting detectors for single photons. The values of the quasiparticle relaxation time (𝜏𝐸) measured for these detectors are affected by pinning properties. Here, we report electric transport properties of NbReN microstrips of different quality. For the strip characterized by high resistivity, and large critical currents and pinning, we estimate a value of 𝜏𝐸 that is almost two orders of magnitude larger compared to that of another strip with a smaller value for the critical current, for which we measure 𝜏𝐸 ∼ 12 ps. This low value is comparable to those reported in the literature for microstrips made of other highly-disordered superconductors. Our results suggest that NbReN microstrips have great potential for the realization of superconducting single-photon detectors, depending on further optimization of their fabrication process and the superconducting properties affected by it.