SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 7: Focus Session: Disordered and Granular Superconductors: Fundamentals and Applications in Quantum Technology II
TT 7.4: Vortrag
Dienstag, 28. September 2021, 14:30–14:45, H6
Disorder-enhanced inelastic relaxation in thin NbN films — Andrey Lomakin1,2, Elmira Baeva1,2, Philipp Zolotov1,2, Alexandra Triznova2, •Anna Kardakova1,2, and Gregory Goltsman1,2 — 1National Research University Higher School of Economocs, Moscow, Russia — 2Moscow Pedagogical State University, Moscow, Russia
Disordered superconducting films is a building block for superconducting nanowire single-photon detectors. A complex physics of such detectors implies a non-equilibrium response, determined by energy relaxation of electrons, namely electron-phonon (e-ph) scattering and phonon escaping times. In practice, one prefers to reduce these values along with optimization of other detector parameters.
Here, we report on experimental study of inelastic relaxation in thin disordered NbN films by measuring of magnetoconductance in the temperature range Tc<T<3Tc. The studied 2.5-nm thick NbN films are characterized by a moderate level of disorder, expressed as 3<kFl<6. From magnetoconductance data, we find out the phase-breaking rate is a sum of two terms, electron-electron (e-e) and e-ph scattering, τφ−1 ∼ Ae−eT + Ae−phTn, where n = 3.5−4 is similar as in work of Sidorova et.al, 2020. We also observe that both e-e and e-ph rates gradually increase with film disorder. The trend for increase of e-e rate with disorder is consistent with scenario of fermionic suppression of superconductivity in NbN films.