Superconductivity in highly disordered NbN nanowires
The topic of superconductivity in strongly disordered materials has attractedsignificant attention.
These materials appear to be rather promising for fabrication of various nanoscale devices such as
bolometers and transition edge sensors of electromagnetic radiation. The vividly debated subject of
intrinsic spatial inhomogeneity responsible for thenon-Bardeen–Cooper–Schrieffer relation
between the superconducting gap and the pairing potential is crucial both for understanding the
fundamental issues of superconductivity in highly disordered superconductors, and for theoperation
of corresponding nanoelectronic devices. Here we report an experimental study of theelectron
transport properties of narrow NbN nanowires with effective cross sections of the order of the
debated inhomogeneity scales. The temperature dependence of the critical current follows the
textbook Ginzburg–Landau prediction for thequasi-one-dimensional superconducting channel
Ic∼(1-T/Tc)3/2. We find that conventional models based on the thephase slip mechanism provide
reasonable fits for the shape of R(T) transitions. Better agreement with R(T) data can be achieved
assuming theexistence of short ‘weak links’ with slightly reduced local critical temperature Tc.
Hence, one may conclude that an ‘exotic’ intrinsic electronic inhomogeneity either does not exist in
our structures, or, if it doesexist, itdoes not affect their resistive state properties, or does not
provide any specific impact distinguishablefrom conventional weak links.