Fluxon dynamics in three stacked Josephson junctions

The motion of fluxons of the same polarity in three vertically stacked Josephson junctions is studied. In this configuration the difference between exterior and interior junctions plays a more important role than in other configurations with several interior junctions. Below the Swihart velocity c/sub -/, the coupling between junctions leads to a repulsion of the fluxons with the same polarity.

Above this critical velocity a fluxon will induce radiation in the neighboring junctions, leading to a bunching of the fluxons in the stacked junctions. Using the Sakai-Bodin-Pedersen model, three coupled perturbed sine-Gordon equations are numerically studied for different values of coupling, damping, and bias parameters.

In a narrow range of velocities bunching occurs. Outside this interval the fluxons split and new fluxons may be created. I-V characteristics are presented