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Different Single-Photon Response of Wide and Narrow Superconducting Mo x Si 1 − x Strips

Authors: Yu. P. Korneeva, N.N. Manova, I.N. Florya, M. Yu. Mikhailov, O.V. Dobrovolskiy, A.A. Korneev, and D. Yu. Vodolazov

Phys. Rev. Applied 13, 024011

Abstract: The photon count rate (PCR) of superconducting single-photon detectors made of MoxSi1x films shaped as a 2-μm-wide strip and a 115-nm-wide meander strip line is studied experimentally as a function of the dc biasing current at different values of the perpendicular magnetic field. For the wide strip, a crossover current Icross is observed, below which the PCR increases with an increasing magnetic field and above which it decreases. This behavior contrasts with the narrow MoxSi1x meander, for which no crossover current is observed, thus suggesting different photon-detection mechanisms in the wide and narrow strips. Namely, we argue that in the wide strip the absorbed photon destroys superconductivity locally via the vortex-antivortex mechanism for the emergence of resistance, while in the narrow meander superconductivity is destroyed across the whole strip line, forming a hot belt. Accordingly, the different photon-detection mechanisms associated with vortices and the hot belt determine the qualitative difference in the dependence of the PCR on the magnetic field.


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