Low Temperature Physics: 38, 353 (2012); https://doi.org/10.1063/1.3699014 (6 pages)
Josephson effect and nonequilibrium superconductivity in superconductor tunnel structures
G.V. Kurdyumov Institute for Metal Physics, 36 Vernadsky Str., Kiev 03680, Ukraine
Received Octouber 18, 2011
Nonequilibrium superconductivity caused by tunnel current injection of quasiparticles was studied. It is found that the instability in the form of a negative voltage jump in the generator current-voltage characteristic (CVC), which leads to an inhomogeneous state, as well as the spatial structure of the inhomogeneous state are very sensitive to weak magnetic fields. The shape of low-resistance tunnel junction CVCs at voltage biases V ≈ 2Δ/e strongly depends on junction dimension and barrier transparency. The results obtained are interpreted by the presence of Josephson vortices (fluxons) in the tunnel generator. The analysis of the nonequilibrium phenomena carried out with due account of Josephson properties of low-resistance tunnel structures has identified a number of novel effects such as nonequilibrium energy-gap suppression at voltage biases V < 2Δ/e, possibility of existence of superconducting state instabilities caused by the tunnel injection, and inhomogeneity of the tunnel injector effect.
PACS: 74.50.+r Tunneling phenomena: Josephson effects;
Key words: Josephson effect, nonequilibrium superconductivity, heterostructure, tunnel effect