Unusial single and multi-fluxon properties
of stacked Josephson junctions

V.M.Krasnov

Department of Microelectronics and Nanoscience Chalmers University of Technology
S-41296, Göteborg, Sweden

Fluxon (Josephson vortex) properties of stacked Josephson junctions (SJJ's) are considerably different from that of single Josephson
junctions. Here I review anomalous single and multi-fluxon properties of SJJ's both in static and dynamic cases: (i) The shape of a moving fluxon may be very unusual, with inverted magnetic inductions in neighbor junctions. (ii) There is only partial or no Lorentz contraction of a moving fluxonin SJJ's. (iii) Fluxons can move with a velocity larger than the electromagnetic phase velocity. Such motion is accompanied by multi-mode Josephson plasma wave (Cherenkov) radiation. (iv) Multiple quasi-equilibrium fluxon modes exist in SJJ's, causing strong fluctuations and bifurcations in transport properties. The existence of multiple fluxon modes is in good agreement with experimental data for both high-Tc mesa structures and low-Tc multilayers and can explain multiple-valued critical current, absence of periodic Fraunhofer modulation of Josephson current and other unusual fluxon-related properties of SJJ's and layered superconductors.