Superconducting thin films of the noncentrosymmetric superconductor Nb 0.18 Re 0.82 were successfully deposited by UHV sputtering technique. X-ray diffraction analysis indicated that the films are polycrystalline, with a preferential (nn0) orientation and the lattice parameter in agreement with the expected single α-Mn cubic phase. A detailed electrical characterization of the samples as a function of the thickness (3.5 nm d 142 nm) was performed both in the normal and in the superconducting states, revealing a well-established superconducting ordering, as well as an estimated value of the upper critical field, μ 0 H c2 , comparable with the Pauli limit. Finally, the symmetry of the order parameter was probed by tunneling spectroscopy on Al/Al 2 O 3 /Nb 0.18 Re 0.82 heterostructures, which provides evidence for a single s-wave superconducting gap.

The suitability of NbRe as a promising material for the design of Superconducting Single Photon Detectors is investigated in order to lower both the minimum detectable photon energy and the recovery time of the devices. Both the low values determined for the quasiparticle relaxation time, τE, and its weak temperature dependence are desirable in the design of fast single photon detectors. Both properties can be further improved by coupling NbRe with a ferromagnetic layer, as demonstrated by estimating the characteristic relaxation rates in NbRe/CuNi bilayers.

Technological applications of NbN thin films may be threatened by the development of magnetic flux avalanches of thermomagnetic origin appearing in a large portion of the superconducting phase. In this work we describe an approach to substantially suppress the magnetic flux avalanche regime, without compromising the upper critical field. This procedure consists of depositing a thin Nb layer before the reactive deposition of NbN, thus forming a bi-layered system. We use AC susceptibility and DC magnetometry to characterize both the single layer films, Nb and NbN, and the bi-layered specimen, as well as calibrated Magneto-Optical Imaging to map the instability regime of the studied samples. Magnetic flux imaging reveals interesting features of the dendritic flux avalanches in the bi-layer system, including halo-like patterns and crossing avalanches.

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