Proximity effect model of ultranarrow NbN strips

Abstract

We show that narrow superconducting strips in superconducting (S) and normal (N) states are universally described by the model presenting them as lateral NSN proximity systems in which the superconducting central band is sandwiched between damaged edge-bands with suppressed superconductivity. The width of the superconducting band was experimentally determined from the value of magnetic field at which the band transits from the Meissner state to the static vortex state. Systematic experimental study of 4.9 nm thick NbN strips with widths in the interval from 50 nm to 20 m, which are all smaller than the Pearl's length, demonstrates gradual evolution of the temperature dependence of the critical current with the change of the strip width.

Metamorphosis of discontinuity lines and rectification of magnetic flux avalanches in the presence of noncentrosymmetric pinning forces

“…In order to test the robustness of the J c (0, B)/J c (π, B) ratio, we consider several cases of holes (no random pinning) at T = 4.5 K and B = 115 mT with rounded corners, where a corner diameter, D, is varied from 0 to 200 nm, in steps of 25 nm. Although D estimated from scanning electron microscopy inspection does not exceed 20 nm, an effective rounding of the vertices could result from a border dead layer, as discussed in [38]. The corresponding J c (0, B)/J c (π, B) ratio presented in Fig.…”

Enhancement of superconductivity in NbN nanowires by negative electron-beam lithography with positive resist

“…Physical phenomena, which cause this deviation and variations of the slope, are out of the scope of the present work. They will be considered in details elsewhere [31].…”

Josephson coupling in the dissipative state of a thermally hysteretic μ -SQUID

“…The etching process can also lead to a reduction in T c due to the appearance of a non-superconducting layer on top, bottom and also on the sides. [46][47][48] However the thickness of such a layer 49,50 is estimated to be ∼ 2 nm only, which leaves a large and effective superconducting channel at the core of the WLs.…”