Superconductive tunneling into NbN deposited near room temperature

Abstract

Articles you may be interested inRoom temperature deposition of superconducting NbN for superconductor-insulator-superconductor junctions Summary Abstract: Low temperature deposition and properties of superconducting NbN by reactive dc magnetron sputtering

Superconducting properties and crystal structures of single-crystal niobium nitride thin films deposited at ambient substrate temperature

“…Hence, the NbN is coupled as strongly as Lead in agreement with other reported results. 17,18 The penetration depth NbN ͑0͒ of the NbN films was calculated from T c , 20 , and ␣ using the relationship given by Orlando et al 19 th ͑0͒ϭ2 1/2 GL…”

Elaboration et caractérisation en hyperfréquences de films minces de NbN

“…L'échantillon (1) possède un gap d'énergie A, = 0394(0)/kTc égal à 2,23, tandis que celui de l'échantillon (2) est d'environ 1,70, ceci pour (Tc/T) > 2. Ces valeurs sont très proches de celles données dans d'autres travaux, où le gap a été mesuré par effet tunnel [5][6][7][8], elles correspondent pour l'échantillon (1) à un couplage fort, tandis qu'on retrouve bien un couplage faible pour les films très minces. Isagawa par contre a trouvé une valeur nettement plus faible, inférieure à 1, qu'il a attribuée à l'existence de zones à conduction non métallique situées aux joints de grains [9].…”

Characterization of superconducting NbTiN films using a Dispersive Fourier Transform Spectrometer

“…which determines the intra-gap states in strong-coupled superconductors. Mattis-Bardeen (MB) theory dictates that for a superconductor α = 2∆ 0 /k b T c , where α is the strong-coupling coefficient 24,25 and 2∆ 0 is the energy gap. For Niobium α ≈ 3.53 26 and even stronger coupling (α > 3.53) was estimated for NbN 24,25 .…”

“…Mattis-Bardeen (MB) theory dictates that for a superconductor α = 2∆ 0 /k b T c , where α is the strong-coupling coefficient 24,25 and 2∆ 0 is the energy gap. For Niobium α ≈ 3.53 26 and even stronger coupling (α > 3.53) was estimated for NbN 24,25 . Equation 3 was obtained using standard MB theory with a simplifying approximation 27 , which is valid in the local limit for strongly-coupled superconductors 28 .…”

“…Still, all the fitting values fall well within the ranges mentioned in the literature. For instance, for NbN α was shown to be even 4.25 24 . For completeness, we included the real and imaginary part of the fitted conductivity curves for films #5 and #6 in Fig.…”