Cherenkov steps and strongly deformed fluxons in finite length window junctions

The long linear window junction with lateral idle region is modelled by an effectively nonlocal sine-Gordon-type equation, and the fluxon dynamics is investigated numerically. The idle region introduces dispersion in the junction, leading to radiation emission via the Cherenkov effect. Cherenkov steps appear on the first zero field step of the I-V characteristics, due to strong nonlinear interaction of the moving fluxon and the radiation. This interaction leads to peculiar, highly nonuniform fluxon motion, which is described phenomenologically. In some cases, the fluxon appears to move discontinuously, jumping from one position to another.